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NOBILIUMTM

Dental Laboratory Materials & Equipment

Technique Manual

NNOOBILIUMBILIUM Technique Manual

11

PREPARED BY: Nobilium CompanyDivision of CMP Industries LLC413 North Pearl Street • Albany, NY 12207

WRITTEN BY: Elmer Rose, CDTManny Alvarez

© 1997 • All Rights Reserved

CONTENTS

Survey & Design .................................................................................2Blockout .............................................................................................3Duplication......................................................................................4-6Refractory Model ............................................................................7-8Waxing...........................................................................................9-10Spruing.............................................................................................11Burnout.............................................................................................12Induction Casting ........................................................................13-14Torch Casting....................................................................................15Finish & Polishing........................................................................16-17Water-Mix Investments................................................................18-24

Aquavest.................................................................................18-19Four Seasons..........................................................................19-21Red Stripe ..............................................................................21-22Green Stripe...........................................................................22-24

Ethyl-Silicate Investments...........................................................25-30Good Earth .............................................................................25-26Good Earth II..........................................................................26-28Yellow Stripe ..........................................................................28-30

Welding.............................................................................................31Trouble Shooting ........................................................................32-35Procedures & Precautions ...............................................................35Bibliography .....................................................................................36Illustrated Dental Terms ..................................................................37Conversion Charts.............................................................................38

SURVEY AND DESIGN

The proper survey and design of the mastermodel is essential to the overall success of aremovable partial denture. The final design isnormally completed by the dentist. However,there are times the laboratory technician isrequired to complete the design process.Should this be the case, the technician mustclosely consult with the dentist concerning thetreatment plan. The technician therefore musthave a thorough knowledge of: 1) the function of the appliance; 2) its esthetic value; and 3) the structure of the oral anatomy. The properdesign together with many of its associated theories become very complex, therefore thedesign process will not be a consideration inthis manual.

Surveying the teeth is the process of studyingthe relative parallelism or lack of parallelism in relationship to the “path of insertion” of theframework. (Path of insertion – the direction ofplacement of the framework as it moves from theinitial point of contact with the rigid oral structureto its terminal rest in the mouth.) Surveying isalso used in determining and outlining theguide plane surfaces used in the direct place-ment of the appliance. In accomplishing the surveying one basically identifies the desirable

undercuts (undercuts necessaryfor retention) and undesirableundercuts (those undercutswhich if involved with the castframework would prevent its insertion).

Surveying requires the useof a surveyor with a fixed oradjustable arm. It is essen-tial to use a stable surveytable that is adjustable andcan be locked into a fixedposition. Analyzing rods,which may be straight ortapered along with undercut gauges of varioussizes including .010, .020 and .030, lead analyz-ing rods, a wax trimmer and blockout trimmerwill be employed in the survey process.

The first step in the surveying procedure is toselect a path of insertion for the framework bytilting the model on the surveyor table andusing the necessary undercut gauges (.010, .020 or .030) to determine the desired depth of undercuts and the proper placement of theundercuts. (Undercut areas are those areas belowthe height of the contour line.) The proper depthof undercuts for the clasp tip is essential.Properly designed and placed, the undercutprovides for the necessary function of the claspand overall retention of the framework. The .010gauge is normally used in the construction ofchrome-cobalt frameworks. Chrome-cobalt is avery rigid alloy and lacks the flexibility neededto engage in deeper undercuts, such as .020 and .030.

Once the proper tilt has been determined thesurvey table is locked in position. Next step isto outline the height of contour using the sur-veyor, analyzing rods and lead. Using a waxed or other type of non lead pencil, transfer thedesign from the study model to the mastermodel. Normally, a lead pencil should not beused in the transfer of design as this type ofpencil may leave a deposit that may be incor-porated in the refractory model and later carried into the final casting. The carbon or leadmay or may not be eliminated during burnout.


22

Nobilium Fixed-Arm Surveyor #8000 and Broken-Arm Surveyor #8001

Each unit comes complete with a locking, tilt-top table with model clamps, and 6 accessory tools stored

under the arm shaft cap.

Surveyor with ModelLocked & Tilted

BLOCKOUT

Once the path of insertion has been deter-mined and the design has been transferred,proceed with the blockout. There are four typesof blockouts used in the construction of remov-able partial denture frameworks: 1) Parallel –using a straight rod, 0° taper to eliminate thewax. This blockout extends from the survey lineto the gingival areas. Thistype of blockout providesfor the maximum contact of the framework and theleast opportunity for foodtraps; 2) Tapered – using a tapered rod of 2° or 6°.This blockout gives you alooser fit and is desirablefor those types of cases

where guide planes maycause some difficulty in seat-ing or where teeth are toofragile; 3) Arbitrary – grossundercut areas not importantto the fit or design of theframework; and 4) Relief – blockout of areas under thesaddles, rugae, tori, clasparms and major connectors.

The parallel and tapered blockout areas aredone using a medium to hard wax. Gross under-cut or arbitrary blockout can be accomplishedusing a softer wax such as boxing wax or clay.The relief blockout requires a wax of uniformthickness such as 22 or 24 gauge pressure sensi-tive wax (a tacky surface relief wax). The edge ofthis wax should be trimmed at a 90° angle to thetissue surface of the cast and 1 mm to 1.5 mmfrom the blockout wax on the abutment teeth.For distal extension cases requiring tissue stops,cutout a 2 mm to 3 mm square from the reliefwax over the crest of the ridge at the most distalpoint for placement of the mesh.

The relief of lingual bars may or may not be

prescribed by the dentist. Lingual bars mayrequire 30 gauge relief, a thin layer of waxflowed onto the area, or no relief, as prescribed.Tori and other sensitive areas may be relievedusing a thin wash of wax flowed over the area inquestion.

Now that the blockout procedure has beencompleted, examine the master model andmake sure the design of the framework is incompliance with the dentist prescription andthe clasps are designed having the properretention and reciprocation. The maxillarymodel may require palatal beading. This shouldbe accomplished before the removal of themaster model from the survey table. The beadline is made using a small sharp instrument andby scooping a smooth scribe line into themodel, the beading in the model shouldbe no deeper than 0.5 mm into the softtissue areas and terminate approxi-mately 4mm from thegingival sulcus. Theinstrument used toscribe the bead lineshould be roundedand give the shape of a “U” rather than a“V” on the cast surface.

Establish tripod marks or triangulation pointson the master modelbefore removal fromthe survey table. Thesemarks will assist in relocation of the pathof insertion should itbe necessary to replacethe model on this oranother survey table atsome future time.

The master model is now ready for duplication.

33


Surveyor “Straight”Rod, Parallel with

0° Taper

Surveyor “Tapered”Rod at 2-6°

Bead Line on Maxillary Model

Tripod Marks onMaster Model

DUPLICATION

Cut the Nobiloid, Nobilflex or InstaloidHydrocolloid into small pieces and feed theminto the Redi-Melt Duplicator, following themanufacturer’s instructions concerning cookdown of the material. The hydrocolloid shouldbe allowed to cook down until all lumps areeliminated. Normally the cooking temperatureof the hydrocolloid is between 190°F (88°C) and195°F (91°C). Once the hydrocolloid is fluid,allow it to cool to a temperature between 130°F(54°C) and 135°F (57°C) for pouring. Generally,the lower the melting or cook down tempera-ture and the lower the holding temperature ofthe hydrocolloid, the longer the life of thehydrocolloid.

When remelting the hydrocolloid after it has beenused and stored in an air tight container, the liq-uid in the bottom of the storage container must bereincorporated into the hydrocolloid when it isremelted. It is vital that this solution be addedto the hydrocolloid when it is remelted as itcontains important salts and minerals essentialto the proper chemical balance of the hydrocol-loid, thus enhancing the life of the hydrocolloid.If there is no liquid solution in the bottom of the storage container, add about 8 ounces ofdistilled water per gallon of hydrocolloid, thiswill aide in maintaining the proper consistency.Replacing water lost during the cooking

and storage process prolongs the life of the hydrocolloid.

The master model will require soaking in warmwater 100°F (38°C) to 110°F (43°C) for 20-30 minutes after the survey and design has beencompleted. Soak-time may vary depending on

the size and density of the model. It is impor-tant that the model be completely saturated so asnot to produce air bubbles in the hydrocolloidimpression. A bell or other type of vacuum maybe used to accelerate the saturation process.Running water should never be used to saturatethe master model as running water will erodethe model thus altering the fit of the framework.The temperature of the water is important as itwill have a direct effect on the temperature ofthe master model when poured. The tempera-ture of the model needs to be close in proximityto the hydrocolloid when it is poured. If themaster model is too cold, when the hydrocolloidcomes in contact with it, there will be an imme-diate chilling or freezing of the hydrocolloid,causing irregularities in the refractory model.Likewise, if the master model is too warm, thehydrocolloid will be absorbed into the pours ofthe stone and cause the colloid to adhere to themodel once it jells.

When the soaking of the master model is completed, remove the model from the waterand gently shake or blow off the excess waterand prepare to pour the hydrocolloid over themaster model.

Select the type of flask to be used, the raisedbase or the flat base flask. In most instances theraised base flask will be used. The raised baseflask will allow for a thicker base on the refractory


44

Redi-Matic Digital Colloid Conditioner #405811 (Left)2 Gallon (7.57 Liter) Capacity, Semi-Automatic Operation

Redi-Melt, Jr. Digital Colloid Conditioner #406711 (Right)3 Gallon (11.36 Liter) Capacity, Fully-Automatic Operation

Master ModelsSoaking in

Warm WaterSet for 20-30minutes at 100°F (38°C)

to110°F (43°C).

model as well as providing for a thick base andmore pronounced sprue hole. The depth of thesprue is of primary consideration at this pointbecause the fines (scum) or doughy investmentwhich forms a thin layer atop the refractorymodel will need to be eliminated, leaving arefractory model with a base at least 1/2" (13mm)thickness at its thinnest point.

Stabilize the master model on the flask base byusing a pliable clay or very soft wax. In the caseof very thin master models, it is important tobuild up the model base with clay. There mustbe at least 1/2" (13 mm) clearance between thehighest point of the master model and the topof the duplicating flask. Pour the hydrocolloidinto the duplicating flask by positioning theflask with the fill hole under the spout of theduplicator, open the dispensing valve and allowa steady stream of hydrocolloid to flow into theflask. The stream should be about the size of apencil. If the pouring process is too slow or thestream is too thin, the hydrocolloid may chill

too rapidly as it travels between the spout andthe flask. This can cause irregularities in theduplicate impression. Conversely, if the pouringis done too rapidly, bubbles and other imperfec-tions may occur in the duplicated model.

Fill the duplicating flask and allow hydrocolloidto exit the vent hole of the flask, this insures the complete filling, prevents “suck-back”imperfections as well as eliminates trapped air bubbles.

Allow the flask to bench set, uncovered, forapproximately 5-10 minutes. The flask may then be placed in a water bath to complete the chilling process. A refrigerated recirculatingwater unit may be used in the cooling process.The temperature of the water should be approximately 55°F (13°C) to 70°F (21°C). Colder water may cause too rapid chilling, freezingor distortion of the hydrocolloid. Allow the flask to remain in the water for 30 minutes. For bestresults, the base of the flask should be the only portion submerged in the water. Whencooling, the hydrocolloid will be drawn downand around the master model. If the flask issubmerged in the water bath, the hydrocolloidis allowed to uniformly cool in the direction ofthe walls of the flask, allowing for the possibilityof distortion of the hydrocolloid impression andultimately the refractory model.


55

Master Models Positioned on Flask BasesModels shown after duplicating with Instaloid

“Concentrated” Hydrocolloid #72-10.(Nobiloid #1012 export only.)

Flat Base Flask #6022

Raised Base Flask#6025

Pouring Hydrocolloid Into Flask From Redi-Melt, Jr.

Note “pencil-size” stream of colloid entering flask.

DuplicatingFlasks Cooling

in Water

Remove the flaskfrom the water ,trim any excessduplicating hydro-colloid from the topof the flask. Openthe bottom of theduplicating flask,remove clay or waxused to extend thebase during theduplicatingprocess. Cut away any hydrocolloidaround the base of the model. Remove thehydrocolloid from the duplicating flask with the stone model intact. Use a gentle tappingand rolling motion to remove the master modelfrom the hydrocolloid. High pressure air shouldnot be used for the removal process as it maycause rips or tears in the hydrocolloid. After the master model has been removed, an air hoseusing gentle pressure may be used to eliminateexcess water from the hydrocolloid impression.

Using the NobilFlex/NobilCoat System(For Other Systems Move to Step B)

A) The NobilCoat should be thoroughly mixed,insuring that all lumps are eliminated and that itpresents a homogenous consistency. Further,the material should be thin, about the consis-tency of a light cream. Should the mixture betoo thick it must be thinned using the NobilcoatThinner.

Pour the Nobilcoatinto the Nobilflexcolloid mold cavityand roll it aroundmaking sure that allsurfaces are coated.Vigorously shake offthe excess coatingleaving a very thincoating. Let themold dry 15 minutesprior to the pouring

of Good Earth, Yellow Stripe or other ethyl-silicate type investment. A longer drying time

for the NobilCoat will not affect the efficiency of the paint on investment, however, too long aperiod of air drying, may have an effect on theaccuracy of your hydrocolloid. If the NobilCoatis not allowed to dry thoroughly, there will be a premature marriage of NobilCoat and therefractory investment, producing rough surfaceson the final casting. (Drying time may be effected byhumidity.)

Note: NobilCoat is not recommended for usewith phosphate type investment.

B) The mold is now ready to receive the refractory material. Using ethyl-silicate or oxy-phosphate investment, refer to the appropriatesection of this manual for directions.

66

Model Removed From ColloidAfter Proper Trimming

The NOBILCOAT/NOBILFLEX SystemYields “Ultra-Smooth” Castings

Coating of Nobilflex Colloidwith Nobilcoat Paint-On


REFRACTORY MODEL

The average size of the refractory model isapproximately 300 grams of investment. (Refer tothe investment of choice listed in this manual for exactpowder and liquid measurements.)

Using the Nobilium Sprue Former, make anindentation in the hydrocolloid and withdrawthe former. Thisprocedure will provide for theplacement of thesprue former in the duplicatingmaterial. Use thelarge end of a #7wax spatula andscoop out the circular area madeby the sprue former. The depthof this cavity should be approximately 5-7 mm.Replace the sprue former and secure it in place.

Usually the former is held inplace by securing it with a rubberband employinglight pressure,spread over thebase of the sprueformer andwrapped aroundthe flask. TheNobilium plasticsprue may also

be held secure by filling the hollow end of theformer with investment, this is the preferredmethod.

Using a laboratory mixing bowl and a heavyduty spatula, mix the investment. Incorporatethe powder into the liquid thoroughly. Careshould be exercised not to mix more invest-ment than can be poured in 3 to 5 minutes, orabout 2-3 models at a time.

Position the flask on vibrator by tilting it slightlyon its side. Scoop investment onto the posterior

area of the hydro-colloid mold letting the investment seekits natural levelin the anteriorsection. Fill theflask to the topusing mild vibra-tion. Allow theflask/investmentto vibrate foradditional 1 minute for most oxy-phosphate and20-30 minutes for most ethyl-silicate investment.Remove the duplicating flask from the vibratorand allow to bench set an additional 25 minutes.As a rule, the total setting time, both vibrationand bench set, for most ethyl-silicate refractorymodels is 55 minutes.

Ethyl-silicaterefractory modelswill have an accumulation ofexcess liquid onthe model basewhich will forminto a gel as itsets. (This liquid/gel is referred to asScum, Fines orDough.) After several minutes of vibration, theaccumulated liquid atop the mold should bepoured off before it sets. Return the flask to thevibrator and continue the vibration until theinvestment fully sets.

Remove the sprue former from the refractorymodel by twisting and pulling it outward, once

the model hasset. Remove thehydrocolloid andrefractory fromthe flask intact.Care must beexercised due tothe fact thatethyl-silicatemodels are attheir weakest in


77

Making Indentation withNobilium Sprue Former

Removal of Indentation forPlacement of Sprue Former

Scooping Investment intoPosterior of Mold

Investment Bench Setting AfterVibration to Remove Bubbles

Careful Peeling of ColloidAway from Investment Model

this green stage. The refractory model isremoved form the hydrocolloid using a sharpknife and creating 4 or 5 slices in the sides ofthe hydrocolloid and peeling the hydrocolloidaway from the model, much like peeling abanana (see bottom of page 7). The model is nowready for trimming.

Trim the refractory model on a dry model trimmer. The model should be trimmed so as to provide a base at least 1/2" (13 mm) thick atits thinnest point. In addition, the base shouldhave angled undercuts (withthe refractorymodel resting onits base theangles should be between 70°and 80° on allsides of therefractory model)to providemechanical locking of themodel during theinvesting process.

Clean out the small end of the sprue hole with asmooth tapered instrument. Round off all sharpedges on the refractory model. Use a gentlestream of air to eliminate all loose particles ofinvestment and debris from the refractorymodel. If there are fractured areas around thesprue hole, they will need to be smoothed toprevent carrying of loose particles of investmentinto the cavity during casting. Use a small,

flexible paint brush and coat the jagged spruehole area with Niranium Precoat Paint-On,Nobilium Green Liquid Paint-On or Nobilcoat.Allow the paint-on to air dry before placing therefractory in the drying oven.

Place the model in the Model Drying Oven at450°F (232°C) for at least 1 hour. Remove therefractory model from the oven and immediately submerge it into rosin dip for approximately 8-10 seconds or as recommended by rosin dipmanufacturer’s instructions..

The rosin dip should be at a temperature of250°F (121°C).

Remove the refractory model from the rosin dipand place the model on its heels or posteriorsection to allow for cooling and drainage prior to waxing.

88


Trimming Refractory on aWheel-Type “Dry” Model

Trimmer #406311

Models Properly Placedon Shelves inModel Drying Oven #405511

Heat at450°F (232°C)for at least 1 hour.

DippingRefractory

Modelinto Rosin DipSubmerge model for

3-5 seconds at250°F (121°C).

WAXING

Prior to beginning the waxing process, thedesign for the framework must be transferredfrom the master model to the refractory model.The transfer of the design is accomplished byusing a waxed pencil. Never use a graphite pen-cil as the deposits left by this type of pencilmay not be completely eliminated duringburnout. Should these graphite deposits remainthey may causepitting and otherimperfections inthe final casting.While transfer-ring the design,examine therefractory modelfor sharpness ofreproduction,making sure thebead lines, ledges, rugae andother landmarksare accurate. It isrecommended that the transfer of the design beaccomplished in the following sequence: major connectors, retentive mesh, tube teeth,facings, clasps & rests and other minor connectors.

Note: One of themost commonconcerns of cast-ing frameworks is,“How much metalshould be used to cast this case?” Theformula for calcu-lating the alloyneeded to castthe framework isas follows andmust be

employed prior to waxing the refractory model:

1) Weigh the refractory model after drying anddipping in rosin and before waxing begins.

2) Weigh the refractory model after waxing andspruing has been completed.

3) Subtract the weight of the un-waxed refractorymodel from the waxed refractory model; multiplythe total by the density of the alloy, and add6 Dwt for the sprue button. This will give the volume of alloy needed to cast a specificframework. Should you find the volume of yourbuttons to be “too large”, reduce the numberused in the equation for the sprue button.

An example of the formula is outlined below:

Weight Refractory 14.4 Gm (9.3 Dwt)Weight Waxed Refractory 20.0 Gm (12.9 Dwt)

Weight Waxed Refractory 20.0 Gm (12.9 Dwt)Subtract (–)

Weight Un-waxed Refractory 14.4 Gm (9.3 Dwt)

TOTAL 5.6 Gm (3.6 Dwt)

Multiply (x)Metal Density 8.0 Gm/cc

TOTAL 44.8 Gm (28.8Dwt)

Add (+)Sprue Former Volume 9.3 Gm (6.0 Dwt)

TOTAL ALLOY VOLUMEREQUIRED FOR CASTING 54.1Gm (34.8Dwt)

This formula works well with any graduate scale,however is recommended for use with grams ordwt measurements. (The volume use in theequation is 6 Dwt for the button, however othernumbers may be substituted depending on thesize of the sprue button desired.) The total volume of alloyneeded or someother “identifyingmark” or numbershould be placedin the sprue holeafter the finalweighing, so theindividual castingthe framework may


99

Transferring Framework Designfrom Master Model to

Refractory ModelNote: Never use a “graphite”pencil,only a “wax-type” pencil as this willeliminate deposits that may cause pitting or other imperfections

in the finished casting.

Nobilium Regular & HardIngot Alloy

Alloy Identifying Mark in Sprue Hole after Weighing

identify the case as well as the amount of alloyneeded to cast the framework (see bottom page 9).This identifying mark may be further transferredto the outer part of the casting ring for identifi-cation purposes. It is recommended that rougebe used to make these identifying marks on therefractory models and casting ring.

The fabrication of a framework or “wax-up” maybe accomplished using a variety of strip waxes,sheet waxes, plastic patterns and free-handwaxing. Free-handing is not widely used due to the availability of plastic and preformed patterns. Generally, patterns are laid down and the only free-hand waxing done is the connecting of the various patterns and theplacement of the rests.

Flow inlay wax in areas such as the bead line,around gingival sulcus, the rugae and toriareas.

Note: It is important to keep this wash of waxthin, as it will have a profound effect on the finalthickness of the cast framework.

This is also the time to add any internal spruingor strengthening bars. When filling the beadline, bring the inlay wax flush with the surface ofthe cast. Also flow inlay wax around the edges ofthe relief pads and into the tissue stops. Nextpaint the major and minor connector areas withtacky liquid. One should be careful not to usetoo much tacky liquid or allow it to puddle. It alsoshould not be applied too thickly under the clasp

and mesh areas as this excess will cause flash inthe final casting.

Once the tacky liquid has had sufficient time todry, begin the placement of the plastic andwaxed patterns. One should have a definite orderin which the wax-up takes place. It is suggestedthat major connectors be placed first, retentiongrids, rests, minor connectors, and finally theexternal finish lines. Once all the connectionshave been made, use a gentle flame from analcohol torch to smooth all the connections.

Note: An alternate method of placing the external finish line may be employed whenstipple sheets are used. The external finish lineis laid in place and the stipple sheet is laid overthe finish line and cut with a warm blade. This produces a clean smooth butt joint for the acrylicand allows for maximum use of the stipple sheetas well as reducing finishing time.

FINISH LINES ARE VERY IMPORTANT ANDTHEIR PROPER CONSTRUCTION CAN NOT BEOVERSTATED!

Super-imposing an external finish line directlyover an internal finish line will create a weak junction between the retentive mesh and themajor connector. This is most evident with free-end saddles in both maxillary and mandibular.The external finish line should be off set 1 mmto 1.5 mm from the internal finish line. This type ofstep in the framework eliminates the weak pointand lessens the possibility of framework failureor breaking of the saddle areas.


1010

Nobilium Offers aComplete Line ofQuality Plastic

Patterns, StippleSheets & Waxes

Nobilium“Wax-Ups”are fabricatedby skilled

dental artisansfrom the finest lab materialsavailable.

Use Nobilium waxes with confidence.

SPRUING

The average case requires the use of 8 gaugeround wax sprues. The shape and direction ofthe sprues are dictated by:

• Design of the framework• Bulkiness of the framework• Flow of the molten alloy

Sprues should be curved in the direction inwhich the metal is to flow. The curving of thesprues helps to eliminate the shrinkagebetween the framework and the reservoir. The sprues are then attached to the bulkierareas of the wax-up. The sprue should be taperedat the point of connection; this connecting pointshould be about half the diameter of the sprue.The reduced diameter of the sprue forces themolten alloy into the cavity under pressure(the venturi effect). The sprues are sealed to thewax-up using a hot spatula and inlay or stickywax.

IMPORTANT: Care must be taken to make surethat the connection points do not produce anysharp angles.

All connections, as well as sprues, should produce curves for best flow of molten alloy.Angles should never be used in the spruingprocess. Sprues come together at the base ofthe cast or at the sprue former, forming asmooth, flowing connection.

Most cases can be successfully cast using threeor four 8 gauge sprues. Exceptions may bemade for those cases having pontics and extraheavy areas. Cases of this type may require the addition of auxiliary sprues and reservoirs.

1111


Typical Spruing Technique of Upper & Lower CasesNote the use of 3 & 4 sprues with 8 gauge wire (sprue) wax.

Nobilium“Round” Wire Wax

is available in eight quality gauges.The suggested 8 gaugewire wax used in Nobilium’s spruingtechnique is #3004.

BURNOUT

The times and temperatures listed in this sec-tion are very general. Consult the specific areasof this manual concerning your investment ofchoice.

Oxy-Phosphate

The cases are invested using metal rings, cardboard rings or plastic rings. Remove thecasting rings and place the mold in a room tem-perature furnace. Heat furnace to 400°F-500°F(204°C-260°C) and hold for 1 hour. Thenincrease temperatures to 1600°F-1800°F (871°C-982°C) and hold for 1 hour before casting.

Ethyl Silicate

Remove the outer ring of the mold, trim thefines or doughy substance from the top of the casting ring. The molds must be trimmedfurther, at least 1/2" (13 mm) below the linejunction of the fines and the regular investment.

This additional trimming eliminates any crack-ing lines that may have been caused during the setting process, thus eliminating crackingduring the burnout. The mold must be allowedto bench set for a total of 1 hour prior to itsintroduction into a warm furnace.

IMPORTANT: The molds should not be allowedto air-dry on the bench for longer than 2 hours.

The longer air drying may cause cracking of themolds once the burnout begins. Those casesrequiring longer time on the bench or out of awarm furnace, should be placed in a humidifiedstate, either a closed plastic bag with a moisttowel or similar closed, moist environment.

Place the invested molds in a warm oven. Thetemperature of the warm oven should be about200°F (93°C). (The Nobilium Gas Furnace pro-vides a climate of about 200°F (93°C) with itscontinuous pilot light.) Thiswarm atmosphere pre-vents cracking of ringswhen ringless system isused. Increase furnacetemperature slowly to desired temperature. Setfurnace at 700°F (371°C) andhold for 30 minutes. This willassure complete drying ofthe molds and completeelimination of wax. Raise the temperature to 1850°F(1010°C) and heat soak for 30 minutes after reachingtemperature. The cases arenow ready to cast.

Note:When using an electric furnace, and anovernight timer, place the cases in a plastic bagalong with a moist towel to prevent excessive drying and premature cracking prior to burnout.


1212

Cases Placed in Plastic Bag with a Moist Towelto Prevent Excessive Drying & Premature Cracking

Trim Mold 1/2” (13 mm)

Below the LineJunction

Eliminates crackinglines caused during thesetting process. This

procedure helps to avoidcracking in burnout.

Gas Burnout Furnace(Shown Above)

18 Case – #8008A45 Case – #8009A

Complete, digital control of programming assures uniform heating without “hot” spots.

Electric Burnout Furnace(Shown Left)

9 Case – #40721120 Case – #407212Complete, digital control with nine, 3-stage heating programs & delay start.

CMP

INDUCTION CASTING

Induction casting discussed in this section will be accomplished in the Modular 5 CastingMachine. Although addressing this specificpiece of equipment, the principles are genericconcerning times and temperatures. Pleaseconsult the manual for your specific casting

machine as to the proceduresnecessary for accomplishing

successful castings.

Induction casting is thepreferred method of casting

due to its ability to provide consistent results.The induction method of casting provides aneven melt of the alloy and less chance of coldspots or overheating. In addition, inductioncasting produces cleaner buttons, if reusing but-tons is a consideration of your laboratory.

Select the volume of alloy needed to cast theframework. (See the mathematical equation on Page 9to calculate the proper amount of alloy required for a specific casting.) If using buttons, make sure theyhave been thoroughly sand blasted, all oxidesremoved and cleaned under running water andcompletely dried. When sprues or buttons areused, it is necessary to add at least 50% newalloy with each button. The addition of this newalloy to the casting process keeps the metalclose to its manufactured pure state.

Turn the on/off switch to the on position. Raisethe coil and place in the locked position. Setthe graphite/ceramic selector switch to theceramic setting. Select the proper setting on the

electronic eye for the melt of the alloy beingused. The set point must be determined foreach individual casting machine. Units mayhave different filters in the sensing eye, there-fore changing the color intensity of the moltenalloy. Once the set point has been determined,it will normally hold true for that alloy duringfuture castings.

Examine the crucibleprior to loading the alloy.Look for excess slag ormetal build-up, cracking,erosion or other imper-fections that may causeforeign particles to becarried into the casting.Load the crucible withthe desired amount ofalloy. Care must be takennot to allow the metal toform a bridge between thewalls of the crucible whenloading, this may cause cracking or fracturing ofthe crucible as the metal expands during heat-ing.

If using a sprue button in addition to new alloy,it is recommended that the old metal be placedin the crucible first, and the new metal beplaced on top of the sprue button. New alloy

tends to meltfaster than oldalloy. Old alloymay have had someof its propertiesaltered fromprevious melts.Like-wise, ifusing splash or pebble alloy,the sprue button should

1313


Modular 5Electronic Induction

Casting Machinew/Digital Electronic

Eye #8205Fully-automatic operation. Castsnon-precious,

semi-precious andprecious alloys injust 60 seconds.

Modular 5 Control Panel

Modular 5Casting Arm Compartment

Modular 5Digital Electronic Eye

be placed in the crucible first. Thebutton

should be allowed to come close to its moltenstate prior to the introduction of the splash orpebble alloy into the crucible.

Close the cover and begin the melting process.Watch the alloy melt until the shadow disap-pears or until able to probe the alloy and causeall pieces to form one mass. When the melt hasbeen accomplished, raise the lid and stop themelt procedure. Load the casting ring into thecasting machine, making sure the hot mold has its sprue hole in proper alignment or relationship to the crucible spout. Once thecasting ring is in place in the cradle, restart the

melt process

again. Continue the melt until the alloy is readyto cast.

Note: Using all new alloy, the same pre-meltprocedure may be employed. This may not benecessary, however, as new alloy melts moreuniformly and generally faster than used alloy.

When the preset temperature has been reachedand the timer expires, the melt coil will auto-matically drop and the spin cycle will initiate.The arm should be allowed to spin a minimumof 15 seconds. The spin of the casting arm maybe terminated by lifting the lid cover or pressingthe red centrifuge stop button.

Rotate the arm until crucible is over the coil.Using the black handle, push the crucible carrier

back over the coil. Raise the coil with the righthand, use the right thumb to move the coilrelease lever to the left, locking the arm in theready position again. Remove the mold fromthe casting arm and place in an area for cooling.The cast case should be allowed to bench set or cool for approximately 45 minutes prior todevesting.

Note: It is not recommended that cases bequenched or the cooling process be accelerated,as this may cause warpage or other distortion of thefinal framework.

Remove the oxide shell or any other slag debrisfrom the crucible.

Examine the crucible for cracking, flaking or erosion that may cause debris to be carried intothe next casting.


1414

Modular 5Casting Armwith mold,

crucible in carrierand working coil.

TORCH CASTING

The torch remains a widely accepted method of casting Nobilium Alloy. This type of castingrequires the use of Oxygen and Acetylene,Oxygen and Propane, or Oxygen and NaturalGas.

The type of torch used is a matter of preference,however, it is recommend a “Harris” type torchwith a multi-orifice tip be utilized. A regulator

that will allow the adjustment of the pressure toabout 8-10 lbs. is required when using Oxygenand Acetylene. The gauge for oxygen should beset at 10 lbs. and the acetylene set at 8 lbs. Ifusing Oxygen and Propane, the oxygen pressureshould be set at 20 lbs. and the propane is setat 10 lbs. If using Natural Gas and Oxygen, theoxygen pressure should be set at 30 lbs. andthe natural gas valve open at full pressure.

The torch flame may be adjusted to the properdimension by increasing or decreasing the flowof oxygen or acetylene. The length of the whiteacetylene feather of the multi-orifice tip shouldextend approximately 1/8" (3 mm) from thetorch tip, while the second inner cone is approx-imately 1-1/2" (38 mm) from the tip of the torch.The remainder of the flame is a brush flame orthe outer cone.

With a wind up casting machine, the arm shouldbe wound approximately 4 turns (the amount ofturns will be determined by the age or strength of thespring). Remove the crucible from the oven or preheating environment and place it in the cradle. Be sure the crucible is free of debris,

carbon or other foreign materials that may haveentered it form the oven or previous castings.

Heat alloy in crucible until it collapses, thenapply flux. Remove mold from furnace andplace it in the casting machine. Release the armand remove the torch simultaneously. Allow armto spin free to a complete stop.

The entire melting process should not takelonger than 1 minute.

1515


CompleteTorch Kits

and Accessoriesare available from Nobiliumfor both

Oxy-Acetylene#36225P23

and Oxy-Gas#36225P24.

FINISHING AND POLISHING

After the cases have been cast, they should beallowed to bench cool 45 minutes prior todeflasking. A hot case should never bequenched, as this may cause warpage. It is notrecommended the cases be placed in direct lineof a fan or placed outside in the rain or snow toexpedite cooling.

The outerinvestmentmay beremoved bytapping with ahammer, toloosen the larger pieces.Grasp thesprue buttonwith pliers andtap sharply on the spruereservoir with a hammer. Repeat the tappinguntil the bulk of the investment has been eliminated.

The case is now ready to be sandblasted.Sandblast thoroughly to remove remaining

investment aswell as tracesof oxides, leaving asmooth, mattesurface. Careshould betaken duringthe sandblast-ing not to useair pressurehigher than 100 psi.

Remove the sprues from the casting using ahigh-speed lathe with a separating disk. Cut the sprues as close to the framework as possible. Thesame disk may be used to remove any flash,fins or other sharp corners and cleaning out narrow areas.

From this point,the choice ofstones becomea matter of technician preference.Abrasive stonesshould be wellbound, clog-freeand have theability to holdtogether whileused in a high-speed lathe.

Use mounted points and stones for shaping thecasting. Each new abrasive should be finer thanthe previous. The primary objective of usingvarious abrasives is to remove the cuts andscratches of the previous abrasive. Care shouldbe exercised when using abrasive stones on therugae and tissue areas. Stoning of these areasis not recommended.

The casting is now ready to be sandblastedonce again. Remove the framework form thesandblaster, wash off excess sand and letthoroughly dry.

The next step in the finishing process is to electro-polish the framework. There are severalpolishing units available for this process. TheNobilium Electro-Polishing unit is a single stageunit utilizing a copper anode. Nobilium ChromePolishing Solution is highly recommended.


1616

Removing Investment by Tappingwith Hammer & Holding with Pliers

Sandblasting Case with Nobilium’sShell/Sandblaster #8017

Removing Sprues with High-SpeedLathe and Separating Disk

Nobilium Electro-Polisher #8018 Shown with1 Gallon (3.79 Liter) Chrome Polishing Solution #5016

The electro-polishing process is designed toeliminate the need for mechanical polishing ofthe tissue side of the framework. Care must betaken to protect clasps, rests and other thin areasof the framework. These areas may be protectedwith a coat of wax or nail polish to preventexcess removal of metal. The electrolytic solu-tion used in the single stage electro-polishingshould cover at least 2/3 of the copper ring and be heated to 120°F-140°F (49°C-60°C). The polishing unit should have the ability toproduce 6-8 amperes.

The average case will require 6-8 minutes inthe acid solution.

Remove the casting from the acid solution, rinse thoroughly and dry. The framework, at

this point, maybe fitted to themaster model.Once the frame-work is properlyseated, rubberpolishing maybegin. The rubber wheelsand pointsshould removeall the remain-ing minutescratches. The

final stages of the polishing process involves theuse of polishing compounds and bristle brushes,felt points and felt or rag wheels, first using thecoarser of the abrasives and graduating to thefiner compound.

The framework may be cleaned using a soft bristle brush and mild soap solution, ultrasonicor steam cleaner.

The framework is now ready for delivery.

1717


Final Finishing with Rubber & FeltWheels and Points

WATER-MIX INVESTMENTS

NOBILIUM “AQUAVEST”

Refractory Models

The master model should be duplicated andallowed to set as described in the “Duplication”section of this manual. Once the colloid hasreached its set, remove the hydrocolloid flaskfrom the chill bath. Submerge the duplicatingflask, with the model intact, into a container of warm water 110°F (43°C) for 10 minutes.Remove the flask from the water. Remove thehydrocolloid and master model from the dupli-cating flask, keeping the two intact. Next gentlyremove the master model from the hydrocolloid.Return the hydrocolloid cavity to the duplicatingflask. Remove any excess water from the innersurface of the impression with a gentle blast ofair pressure.

Mix 28 cc of water to 200 grams of Aquavestfor each refractory model, always rememberingto add the powder to the liquid. Spatulate byhand until all particles of investment are moist.This should take approximately 30 seconds, followed by mechanical mixing for an additional30 seconds.

Place sprue hole former in desired position inthe hydrocolloid. Secure the sprue former inplace with a rubber band wrapped looselyaround the flask. Position the flask on the vibra-tor, tilting it slightly on its side. Fill the flask partially with the investment mixture thenvibrate the investment from the hydrocolloidimpression back into the bowl. This procedureinsures that air is not trapped between thehydrocolloid and the investment. Refill thehydrocolloid cavity with investment to the topof the mold or to the top of the sprue former.Remove the duplicating flask from the vibrator.

Allow to bench set for 45-55 minutes.

CAUTION: During the summer or when the tem-perature goes above 80°F (27°C), keep watertemperature at about 70°F (21°C), otherwise theinvestment will set too rapidly. It is advisable to

pour no more than two molds at a time.

After the refractory model has bench set forapproximately 10 minutes and the initial set of the investment has taken place, the sprueformer may be removed.

Allow the refractory model to set 35-45 min-utes longer and then remove the colloid andrefractory model from the flask very carefully.

The hydrocolloid and the refractory modelshould be removed as one unit. The model isremoved form the hydrocolloid using a sharpknife creating 4 to 6 slices down the sides of thehydrocolloid and peeling the hydrocolloid awayfrom the refractory model, like peeling abanana.

The model is ready for trimming. Trim therefractory model on a dry model trimmer. Themodel should be trimmed in a manner so as toprovide a base at least 1/2" (13 mm) thick, at its thinnest point. In addition, the base shouldhave angled undercuts on the base between 70°and 80° to provide for mechanical locking of themodel during the investing process.

Clean out the small end of the sprue hole with asmooth tapered instrument. Round off all sharpedges of the refractory model. Use a gentlestream of air to eliminate all loose particles ofinvestment anddebris from the refractory model.If there are fractured areas around the spruehole, they should be smoothed to prevent looseparticles of investment from entering the cavityduring casting. Use a small flexible paintbrushand coat the jagged areas with Green Paint-On.Allow the paint-on to air dry 10 minutes prior to placing the refractory model into the modeldrying oven.

Place the model in the Model Drying Oven at450°F (232°C) for 1 hour.

Note: Should the oven not be able to reach thistemperature, the refractory model should beallowed to remain in the oven an additional 1/2 hour to insure complete dehydration. Thetemperature difference between the refractory


1818

model and the dip should be approximately200°F (93°C).

While the refractory model is dehydrating, pre-heat the rosin dip to 250°F (121°C). Remove therefractory model from the oven and completelysubmerge it into the hot rosin dip and allow toremain in the dip 3-5 seconds.

Note: Longer time periods in the rosin maycause the refractory to soak up too much of therosin or cause pooling and ultimately producingfins, rough castings or other imperfections in the finalcast product.

Remove the refractory model from the rosin dipand place the model on its heels or posteriorsection to allow for cooling and drainage.

Investing

Once the wax-up has been completed and thecase sprued, lute the model to the flask basewith hot wax. Place casting ring around thewaxed model either using a liner and splitmetal, plastic or cardboard ring. If a plastic ringis used, it should be removed when the invest-ment reaches its initial set. Ensure a minimum of 1/4" (6 mm) distance exist between the linerand the wax-up. Seal the ring to the base. Pourdebubblelizer into the ring to cover model andwax-up. Utilize a soft bristle paint brush to gen-tly wash the surface of the wax-up to eliminatedebris, air entrapment as well as eliminating the surface tension of the wax-up and allow theinvestment to flow smoothly. Pour off the excessor remaining debubblelizer and gently air drythe wax-up using light air pressure.

Mix 84 cc of water to 600 grams of Aquavest.Spatulate the investment by hand for 30 secondsfollowed by mechanical mixing for an additional30 seconds. Cover the entire casewith the invest-ment mixture, utilizing moderate vibration during the initial pour.

Allow the mold to set 45 minutes beforeremoving the ring, trimming and placing inburnout furnace.

If a plastic ring is used, it should be removed as theinvestment reaches its initial set.

Burnout

Place the casting ring in a room temperature furnace. Heat furnace to 400°F-500°F (204°C -260°C) and hold for 1 hour. Increase the furnacetemperature to 1600°-1800°F (871°C - 982°C)and hold for 1 hour before casting.

Once casting is complete, bench cool the cast-ing 45 minutes to 1 hour before devesting.

NIRANIUM “FOUR SEASONS”

Refractory Models

The master model should be duplicated andallowed to set as described in the “Duplication”section of this manual. Once the colloid hasreached its set, remove the hydrocolloid flaskfrom the chill bath. Remove the hydrocolloidand master model from the duplicating flask,keeping the two intact. Gently remove the master model from the hydrocolloid. Return the hydrocolloid cavity to the duplicating flask.Remove any excess water from the inner surfaceof the impression with a gentle blast of air pressure.

Add 22 cc of water to 198 grams of FourSeasons investment and spatulate vigorouslyuntil thoroughly mixed. Place sprue hole formerin desired position in the hydrocolloid. Securethe sprue former in place with a rubber bandloosely wrapped around the flask. Position theflask on vibrator, holding it firmly with one handand tilting it slightly on its side. Fill the flask tothe top using mild vibration. Allow the invest-ment to vibrate for an additional 10 minutes.Remove the duplicating flask from the vibratorand allow to bench set for another 45 minutes.

The total setting time for refractory model is55 minutes.

CAUTION: During the summer or when the tem-perature goes above 80°F (27°C), keep water

1919


temperature at about 70°F (21°C), otherwise theinvestment will set too rapidly. It is advisablethe pour no more than two mold at a time.

The refractory model is removed with a sharpknife by creating 4 to 6 slices, from top to bottom, and peel the hydrocolloid away fromthe model, like peeling a banana. The model is now ready for trimming. Trim the refractorymodel on a dry model trimmer. The modelshould be trimmed in a manner so as to providea base at least 1/2" (13 mm) thick, at its thinnestpoint. In addition, the base should have angledundercuts on the base between 70° and 80° toprovide for mechanical locking of the modelduring the investing process.

Clean out the small end of the sprue hole with a smooth tapered instrument such as a pencil,round off all sharp edges of the refractorymodel. Use a gentle stream of air to eliminateall loose particles of investment and debrisfrom the refractory model. If there are fracturedareas around the sprue hole, they will needto be smoothed to prevent carrying of looseparticles of investment into the cavity duringcasting. Use a small flexible paint brush andpaint the jagged sprue hole area with GreenLiquid Paint-On. Allow paint-on to air dry atleast 5-7 minutes before placing the refractorymodel in the drying oven.

Place the model in a hot 450°F (232°C) for 1 hour.

Note: Should the oven not be able to reach thistemperature, the refractory model should beallowed to remain in the oven an additional 1/2 hour to insure complete dehydration. Thetemperature difference between the refractorymodel and the dip should be approximately200°F (93°C).

Removemodel fromdrying oven and completelysubmerge model in rosin dip approximately 3-5seconds. The rosin dip should be at a tempera-ture of 250°F (121°C).

Note: Longer time periods in the rosin maycause the refractory to soak up too much of the

rosin or cause pooling and ultimately producingfins, rough castings or other imperfections in the finalcast product.


Investing

Once the wax-up has been completed and thecase sprued, lute the model to the flask basewith hot wax. Place casting ring around thewaxed model either using a liner and splitmetal, plastic or cardboard ring. (If a plastic ring isused, it should be removed when the investment reachesits initial set.) Ensure a minimum of 1/4" (6 mm)distance exist between the liner and the wax-up.Seal the ring to the base. Pour debubblelizerinto the ring to cover model and wax-up. Utilizea soft bristle paint brush to gently wash the surface of the wax-up to eliminate debris, airentrapment as well as eliminating the surfacetension of the wax-up and allow the investmentto flow smoothly. Pour off the excess or remain-ing debubblelizer and gently air dry the wax-upusing light air pressure.

For average cases, mix 66-68 cc of water with594 grams of Four Seasons investment. Handspatulate for 30 seconds and mechanically foran additional 30 seconds and pour into the ring.Vibrate for 10 minutes for best results.

Allow case to bench set for 1 hour.

Remove the base and place in furnace withmetal ring intact. (If using plastic split ring, removering after investment has reached its initial set.)

Burnout

Place the mold in a room temperature furnace.Heat furnace to 500°F (260°C) and hold for 1hour. Increase the furnace temperature to1850°F (1010°C) and hold for 30 minutes beforecasting.

Bench cool the casting 45 minutes to 1 hourbefore devesting.


2020

Note:More rapid run-up of the mold in theburnout furnace will cause fins and cracking of the mold.

NOBILIUM “RED STRIPE”OXY-PHOSPHATE INVESTMENT

Refractory Models

The master model should be duplicated andallowed to set as described in the “Duplication”section of this manual. Once the colloid hasreached its set, remove the hydrocolloid flaskfrom the chill bath. Submerge the duplicatingflask, with the model and hydrocolloid intact,into a container of warm water 110°F (43°C) for10 minutes.

Note: It is essential that this step not be overlooked as it brings the hydrocolloid to a tem-perature that accelerates the setting time of theinvestment.

Remove the flask from the water. Remove the hydrocolloid and master model from theduplicating flask, keeping the two intact. Gentlyremove the master model from the hydrocolloid.Return the hydrocolloid cavity to the duplicatingflask. Remove any excess water from the innersurface of the impression with a gentle blast ofair pressure.

Place sprue former in position and, securingwith a rubber band, apply light pressure aroundthe flask.

Mix 25 cc of water to 200 grams of Red Stripeinvestment for each refractory model. Add thepowder to the water and spatulate by hand for 30 seconds, followed by mechanical mixing foran additional 30 seconds.

CAUTION: During the summer or when tem-peratures go above 80°F (27°C), keep watertemperature at about 70°F (21° C) otherwise the investment will set too rapidly. It is advisablenot to pour more than 2 refractory models at atime.

Vibrate mixed investment into the hydrocolloidimpression, filling it to the top of the flask or thesprue former and allow the flask to continue tovibrate for 1 minute.

Remove the flask from the vibrator and let itbench set for 20-35 minutes.

After the refractory model has bench set, removethe sprue former from the refractory model, thenremove the refractory model and hydrocolloidfrom the flask. At this point the refractory modelmay be removed from the hydrocolloid using asharp knife making 4 to 6 slices in the hydrocol-loid from the top to the bottom and peeling itaway from the refractory model as if peeling abanana.

The refractory model is now ready for trimming.Trim the refractory model on a dry model trim-mer. The model should be trimmed in a mannerso as to provide a base at least 1/2" (13 mm)thick, at its thinnest point. In addition, the baseshould have angled undercuts on the basebetween 70° and 80° to provide for mechanicallocking of the model during the investingprocess.

Clean out the small end of the sprue hole with a small, tapered instrument such as a pencil.Round off all sharp edges on the refractorymodel. Use a gentle stream of air to eliminateall loose particles of investment and debrisfrom the refractory model. If there are fracturedareas around the sprue hole, they should besmoothed to prevent loose particles of invest-ment from being carried into the cavity duringthe casting process. These areas may be furthersmoothed by using a small, flexible paint brush,painting the jagged edges with Green LiquidPaint-On or Niranium Precoat Paint-On. Allowthe paint-on to air dry at least 5-7minutes beforeplacing the refractory model into the ModelDrying Oven.

Place the trimmed refractory model into the Model Drying Oven at 450°F (232°C) for 1 hour.

2121


Note: Should the oven not be able to reach thistemperature, the refractory model should beallowed to remain in the oven an additional1/2 hour to insure complete dehydration. Thetemperature difference between the refractorymodel and the dip should be approximately200°F (93°C).

Carefully removing the refractory from the oven,completely submerge it into the rosin dip andallow to remain for approximately 3-5 seconds.The rosin dip should be at a temperature of250°F (121°C).



Investing

Nobilium Plastic Flask, Cardboard or Split Ringsmay be used for the investing process. Lute themodel to the flask base with hot wax. Place cast-ing ring around the waxed model and secure tothe base, either with the metal plastic or splitring. (If a plastic ring is used, the outer ring should beremoved when the investment reaches its initial set.)Ensure that a minimum of 1/4" (6 mm) distanceexist between the liner and the wax-up. Seal thering to the base. Pour debubblelizer into thering and cover model and wax-up. Utilize a softbristle paint brush to gently wash the surface ofthe wax-up to eliminate debris, air entrapmentas well as eliminating the surface tension of the wax-up and allow the investment to flowsmoothly. Pour off the excess or remainingdebubblelizer and gently air dry the wax-upusing light air pressure.

To invest the case, measure 80 cc of water at70°F-75°F (21°-24°C) and 640 grams of RedStripe investment, hand spatulate 30 seconds,followed by mechanical mixing for an additional30 seconds.

Place flask with attached waxed model on thevibrator. Pour investment slowly in flask. Withflask in hand and slightly tilted on its side,vibrate all the investment back into the bowluntil wax-up is exposed. Keep flask vibrating to eliminate any entrapped air around criticalareas of the case. Slowly vibrate investmentback into the flask, filling it completely to thetop of the flask or top of the sprue of sprueformer, if inverted spruing is used. Removeflask immediately from the vibrator.

Allow the case to set 20 minutes before remov-ing flask. Let invested ring set an additional 25 minutes before placing the ring into theburnout furnace.

Burnout

Place the mold into a room temperature furnace,heat furnace to 500°F (260°C) and hold for 1 hour.Increase the temperature to 1800°F (982°C) andhold for 30 minutes before casting.

CAUTION: Too rapid rise in temperature in thefurnace may cause fins and cracking of the mold.


NOBILIUM “GREEN STRIPE”OXY-PHOSPHATE INVESTMENTw/Special Liquid

Nobilium’s Green Stripe is a fine-grained, highheat “cristobalite enhanced” investment for castpartial denture frameworks. A special all-seasonliquid is provided for the refractory model toinsure an accurate fit of the finished framework.Green Stripe has been developed to be com-patible with Nobilium All-Purpose Noboloidand Instaloid hydrocolloids. It is also compatiblewith Polysilaxane Rubber duplicating systems.

Refractory Models

The mater model should be duplicated andallowed to set as described in the “Duplication”section of this manual. Once the colloid has


2222

reached its set, remove the hydrocolloid flaskfrom the chill bath. Prepare the special liquid.The recommended liquid dilution for mostrefractory models is three (3) parts Green Stripeliquid to one (1) part water. This proportioncan be varied to increase or decrease expansion.

Less water will increase expansion.

In a wet bowl, add exactly 21 cc of prepared liquid to 150 grams of Green Stripe investmentfor each refractory model, always rememberingto add the powder to the liquid. Spatulate byhand 15 seconds until the investment is wet,then mechanically mix for 40-60 seconds. If handmixing only, spatulate vigorously until mixedthoroughly. Place sprue hole former in desiredposition in the hydrocolloid. Secure the sprue former in place with a rubberband wrappedloosely around the flask. The Nobilium plasticsprue may also be held secure by filling the hollow end of the former with investment.Position the flask on the vibrator, tilting it slightlyon its side, fill the flask with the investmentmixture.

Remove the duplicating flask from the vibratorand allow to bench set for 1 hour.

CAUTION: During the summer or when the tem-perature goes above 80°F (27°C), keep liquidtemperature at about 70°F (21°C), otherwise theinvestment will set too rapidly. It is advisable topour no more than 2 refractory models at a time.

After the mold has bench set for 1 hour, thesprue former may be removed from the invest-ment refractory. Remove the hydrocolloid andthe refractory model from the duplicating flaskin a single unit. The model is removed form thehydrocolloid using a sharp knife to create 4 to 6slices down the sides of the hydrocolloid andpeeling the hydrocolloid away from the refracto-ry model as if peeling a banana.

The refractory model is now ready for trimming.Trim the refractory model on a dry model trim-mer. The model should be trimmed in a mannerso as to provide a base at least 1/2” (13 mm)thick, at its thinnest point. In addition, the base

should have angled undercuts on the basebetween 70° and 80° to provide for mechanicallocking of the model during the investingprocess.Clean out the small end of the sprue hole with a small, tapered instrument such as a pencil.Round off all sharp edges of the refractorymodel. Use a gentle stream of air to eliminateall loose particles of investment and debrisfrom the refractory model. The density of thisinvestment produces a hard and smooth spruearea, should there be any fractured areasaround the sprue hole, they should besmoothed to prevent loose particles of invest-ment from entering the cavity during casting.Use a small flexible paintbrush and coat thejagged areas with Green Paint-On. Allow thepaint-on to air dry 10 minutes prior to placingthe refractory model into the Model DryingOven.

Place the trimmed model into the ModelDrying Oven at 450°F (232°C) for 1/2 hour.


While the refractory model is dehydrating, pre-heat the rosin dip to 250°F (121°C). Remove therefractory model from the oven and completelysubmerge it into the hot rosin dip and allow toremain in the dip for no more than 10 seconds.


Remove the refractory model from the rosin dipand place the model on its heels or posteriorsection to allow for cooling and drainage. IfNobilium Safe Dip or Special Hard Rosin Dip is used follow label directions.

2323


Investing

Once the wax-up has been completed and thecase sprued, apply Nobilium Green Paint-On. If Green Paint-On is not used, apply CB-30Crown and Bridge “Debubblelizer” to waxedareas and follow directions on the label. Lutethe model to the flask base with hot wax. Placecasting ring around the waxed model andsecure to the base, either with metal, plastic orsplit ring. (If a plastic ring is used, the outer ring shouldbe removed when the investment reaches it initial set.)

To invest the case, mix 84 cc of PLAIN WATERto 600 grams of Green Stripe investment. Addinvestment to water and spatulate thoroughly ormechanically for 45 seconds. Vibrate flask andslowly fill with investment, utilizing moderatevibration.

Note: If additional expansion is desired, a 50%dilution of Green Stripe special liquid can beused for the outer investment.

Allow the invested ring to set 1 hour beforedeflasking, trimming and placing in burnoutfurnace.

Burnout

Place the mold into a room temperature furnace,heat furnace to 500°F (260°C) and hold for 1 hour.Increase the temperature to 1800°F ( 982°C) andhold for 1 hour before casting.

CAUTION: Too rapid rise in temperature in thefurnace may cause fins and cracking of the mold.


ATTENTION: Important “Green Stripe”processing information.

Be certain to remove any excess moisture from thecolloid mold before pouring the refractory.

Allow the colloid to warm slightly if it has beensubjected to very cold temperatures.

Exercise caution when removing the refractoryfrom the colloid. Be certain to section the colloid toavoid breaking any teeth. Once the refractory is dehydrated in the drying oven and rosindipped, the working model is hard, smooth and easy to wax on without fear of refractory distortion.


2424

ETHYL-SILICATE INVESTMENTS

“GOOD EARTH” INVESTMENT

Prepare the liquid by emptying the entire con-tents of solution “A” into the Binder bottle. Capbottle tightly, shake well, uncap lid to releasepressure, tighten cap again and shake until liq-uid becomes hot, approximately 140°F-150°F(60°C - 66°C). Loosen the cap again to releasethe pressure, and let stand for 1-1/2 hour oruntil liquid comes to room temperature of 70°F(21°C) before using. Prepared liquid may berefrigerated or placed in cold water to achievedesired temperature.

Keep mixed liquid in refrigerator when not in use.

Note: DO NOT prepare more liquid than canbe used in 2-3 days.

For smaller quantities, mix: one (1) part ofSolution “A” to nine (9) parts of Binder. Follow the directions as prescribed above.

Refractory Models

The master model should be duplicated andallowed to set as described in the “Duplication”section of this manual. Once the colloid hasreached its set, remove the hydrocolloid flaskfrom the chill bath. Remove the master modelform the hydrocolloid and place sprue hole former in position and secure, using a rubberband extending loosely around the flask.

Mix investment powder with prepared, roomtemperature liquid in a rubber bowl. Mix to amedium consistency (37 cc of prepared liquidto 195 grams of investment) and vibrate into the hydrocolloid impression using moderatevibration. Fill the mold to the top of the ring orthe sprue former. Allow the flask to remain onthe vibrator and vibrate at moderate setting for20 minutes.

Pour off excess liquid and allow the investedring to bench set an additional 30 minutes.

After the refractory model has bench set,

remove the sprue former from the refractorymodel, then remove the refractory model andhydrocolloid from the duplicating flask. Separatethe refractory model from the hydrocolloid,using a sharp knife, making 4-6 slices from topto bottom of the hydrocolloid mold, and peelaway the hydrocolloid as peeling a banana. At this point there should be about 1/8”-1/4” (3-6 mm) of fine doughy investment on the base of the refractory model.

These fines must be removed by dry grindingon a model trimmer.

Care must be taken to remove all fines or doughyareas on the refractory model. The base of therefractory model should be at least 1/2" (13 mm)at its thinnest point. In addition, the baseshould have angled undercuts between 70° and 80° to provide for mechanical locking of the model during the investing process.

Use a low pressure air hose to remove excessdebris from refractory model. Clean out thesmall end of the sprue hole with a small taperedinstrument, such as a pencil, and round off allsharp edges on the refractory model. Use gentlestream of air to eliminate all loose particles of investment and debris from the refractorymodel. If there are fractured areas around thesprue hole, they should be smoothed to pre-vent loose particles of investment from beingcarried into the cavity during the castingprocess. These areas may be further smoothedby using a small flexible paint brush, paintingthe jagged edges with paint-on investment.Allow the paint-on to air dry at least 10 minutesbefore placing the refractory model into theModel Drying Oven.

Place the trimmed model in Model DryingOven at 450°F (232°C) for 1 hour.


2525


Remove model from oven and submerge refractory model in rosin dip approximately 3-5 seconds. The rosin dip should be at a temperature of 250°F (121°C).


Investing

A thin wash of Nobilium Green Liquid Paint-On,NobilCoat or Niranium Precoat Paint-On may be applied to the wax surfaces and the sprues.Vigorously shake off excess of the paint-on,leaving a layer thin enough to see all colors ofwax-up coming through the paint on material.Allow the NobilCoat to dry 15 minutes or theNobilium Green Liquid Paint-On or NiraniumPrecoat Paint-On to dry 7 minutes prior to pouring the outer ring of investment.

Mix investment with prepared liquid (at roomtemperature) in rubber bowl to medium consis-tency. For average cases use 112 cc of liquid to600 grams of investment. Vibrate into the flaskand leave on the vibrator at a moderate settingfor 20 minutes. Remove the outer ring and scrapeoff the built-up area of 1/4"-1/2" (6-13 mm) offines, then trim the ring or flask on the modeltrimmer, making sure to trim the ring at least1/4"-1/2" (6-13 mm) below the doughy junctionof the ring.

Allow the ring to bench set for not less than 45 minutes and not more than 1 hour beforeplacing case in the furnace.

Burnout

Place case in a warm furnace about 200°F-300°F(93°C-149°C) and bring temperature of furnaceup slowly to 500°F (260°C). Hold at this temper-ature for 30 minutes and then raise slowly toreach 1850°F-1900°F (1010°C-1038°C).

Heat soak at this temperature for approxi-mately 30 minutes before casting.

Note: Should the oven not have a pilot light to

keep the temperature at about 200°F (93°C) therings should be placed in the oven in a plasticbag with a moist towel. This procedure will prevent the cases from cracking and drying outtoo much prior to burnout.


Note: For optimum results, investment shouldtake about 20-25 minutes to reach its initial set.Setting time varies with changes in temperatureand humidity. Adjust setting time to compensatefor conditions. Solution “A” controls settingtime. More solution “A” speeds setting time whileless solution “A” retards setting time.

GOOD EARTH II INVESTMENT

Prepare the liquid by emptying the entire con-tents of solution “A” into the Binder bottle. Capbottle tightly, shake well, uncap lid to releasepressure, tighten cap again and shake until liq-uid becomes hot, approximately 140°F-150°F(60°C-66°C). Loosen the cap again to release the pressure, and let stand for 1-1/2 hours oruntil liquid comes to room temperature of 70°F(21°C) before using. Prepared liquid may berefrigerated or placed in cold water to achievedesired temperature.


Note: DO NOT prepare more liquid than canbe used in 2 -3 days.

For smaller quantities, mix: one (1) part ofSolution “A” to eight (8) parts of Binder.Follow the directions as prescribed above.

Refractory Models

The master model should be duplicated andallowed to set as described in the “Duplication”section of this manual. Once the colloid hasreached its set, remove the hydrocolloid flaskfrom the chill bath. Remove the master modelform the hydrocolloid and place sprue hole former in position and secure, using a


2626

rubber band extending loosely around the flask.

Mix investment powder with prepared, roomtemperature liquid in a rubber bowl. Mix to amedium consistency (37 cc of prepared liquidto 195 grams of investment) and vibrate intothe hydrocolloid impression using moderatevibration. Fill the mold to the top of the ring orthe sprue former. Allow the flask to vibrate atmoderate setting for 5 minutes.

Pour off excess liquid and allow the investedring to bench set an additional 30 minutes.

After the refractory model has bench set,remove the sprue former from the refractorymodel, then remove the refractory model andhydrocolloid from the duplicating flask. Separatethe refractory model from the hydrocolloid,using a sharp knife, making 4-6 slices from topto bottom of the hydrocolloid mold, and peelaway the hydrocolloid as peeling a banana. At this point there should be about 1/8”-1/4” (3-6 mm) of fine doughy investment on the base of the refractory model.

These fines must be removed by dry grindingon a model trimmer.

Care must be taken to remove all fines or doughyareas on the refractory model. The base of therefractory model should be at least 1/2” (13 mm)at its thinnest point. In addition, the baseshould have angled undercuts between 70° and 80° to provide for mechanical locking of the model during the investing process.

Use a low pressure air hose to remove excessdebris from refractory model. Clean out thesmall end of the sprue hole with a small taperedinstrument, such as a pencil, and round off allsharp edges on the refractory model. Use gentlestream of air to eliminate all loose particles ofinvestment and debris from the refractorymodel. If there are fractured areas around thesprue hole, they should be smoothed to pre-vent loose particles of investment from beingcarried into the cavity during the castingprocess. These areas may be further smoothedby using a small flexible paint brush, painting

the jagged edges with paint on investment.Allow the paint-on to air dry at least 10 minutesbefore placing the refractory model into theModel Drying Oven.

Place the trimmed model in Model DryingOven at 400°F (204°C) for 30 minutes.


Remove model from oven and submerge refractory model in Rosin Dip approximately 8-10 seconds. The Rosin Dip should be at atemperature of 250°F (121°C).


Investing

A thin wash of Nobilium Green Liquid Paint-On,NobilCoat or Niranium Precoat Paint-On may be applied to the wax surfaces and the sprues.Vigorously shake off excess of the paint-on,leaving a layer thin enough to see all colors ofwax-up coming through the paint on material.Allow the NobilCoat to dry 15 minutes or theNobilium Nobilium Green Liquid Paint-On orNiranium Precoat Paint-On to dry 7 minutesprior to pouring the outer ring of investment.

Mix investment with prepared liquid (at roomtemperature) in rubber bowl to medium consis-tency. For average cases use 112 cc of liquid to600 grams of investment. Vibrate into the flaskand leave on the vibrator at a moderate settingfor 5 minutes. Remove the outer ring and scrapeoff the built-up area of 1/4”-1/2” (6-13 mm) offines, then trim the ring or flask on the modeltrimmer, making sure to trim the ring at least1/4”-1/2” (6-13 mm) below the doughy junctionof the ring.

2727


Allow the ring to bench set for not less than 45 minutes and not more than 1 hour beforeplacing case in the furnace.

Burnout

Place case in a warm furnace about 200°F-300°F(93°C-149°C) and bring temperature of furnaceup slowly to 500°F (260°C). Hold at this temper-ature for 30 minutes and then raise slowly toreach 1850°F -1900°F (1010°C -1038°C ).

Heat soak at this temperature for approxi-mately 30 minutes before casting.

Note: Should the oven not have a pilot light tokeep the temperature at about 200°F (93°C), therings should be placed in the oven in a plasticbag with a moist towel. This procedure will prevent the cases from cracking and drying outtoo much prior to burnout.


Note: For optimum results investment shouldtake about 20 -25 minutes to reach its initial set.Setting time varies with changes in temperatureand humidity. Adjust setting time to compensatefor conditions. Solution “A” controls settingtime. More solution “A” speeds setting time whileless solution “A” retards setting time.

REGULAR & NEW IMPROVED “YELLOW STRIPE” INVESTMENT

Prior to working with these investments, mixingof the liquids is required. The liquids are pre-pared in 3 parts, “C”, “D”, and “E”. “D” and “E”liquids come prepared and require no addition-al pre-mixing. However, “C” liquid is packagedin a concentrate to reduce shipping weight. Addcold water to liquid in “C” container to equal 1 gallon of liquid. (This procedure now yieldsthree equal parts of “C”, “D” and “E” liquids.)

The proportions of liquid in mixing for use inthe investing process are as follows:

2 parts by volume of liquid “C”2 parts by volume of liquid “D”2 parts by volume of liquid “E”

Pour 2 parts by volume of liquid “E” into a glass measuring container. Transfer this liquid to a plastic jug with a screw top. Add 1 part by volume of liquid “C” (the remaining 1 part will beadded later). Cover the container tightly and shakeliquids vigorously in container. After a minute or two the container will feel warm, indicatingthe hydrolysis is taking place. Loosen the coverand shake the liquids for a few more secondsand again release the pressure. Repeat this procedure until liquid feels hot to the touch –approximately 140°F (60°C).

Add slowly 2 parts by volume of liquid “D”. Add1 part by volume of Liquid “C” and shake. Placecovered container in refrigerator, or allow coldwater to run over outside of container until thetemperature drops to 70°F (21°C). The liquid isnow ready to use.


Note: DO NOT prepare more liquid than canbe used in 2-3 days. One pint of mixed liquid is enough to process 3 average size cases.

Refractory Models

The master model should be duplicated andallowed to set as described in the “Duplication”section of this manual. Once the colloid hasreached its set, remove the hydrocolloid flaskfrom the chill bath. Remove the master modelfrom the hydrocolloid. Place sprue hole formerinto position.

For each model, use 27 cc of prepared liquidto 170 grams of investment.

Mix Yellow Stripe Investment and prepared liquid in a bowl, spatulating about 1 minute.Vibrate investment into the impression filling itto the top. Set mold aside on vibrator and con-tinue moderate vibration until investment hasset (accumulated liquid can be poured off the top beforethe investment is completely set).


2828

The setting time will vary from 20 to 30minutes, depending on room, powder andliquid temperatures.

Remove flask from the vibrator and allow tobench set for an additional 25 minutes. After themodel has bench set, remove the sprue formerfrom the refractory model, then remove therefractory model and hydrocolloid from the flaskintact. The refractory model is then removedfrom the hydrocolloid using a sharp knife andcreating 4-6 slices in the hydrocolloid, from thetop to the bottom, and peeling the hydrocolloidaway like peeling a banana. At this point thereshould be about 1/8"-1/4" (3-6 mm) of fines ordoughy investment on the base of the refractorymodel. These fines must be removed by drygrinding on a model trimmer. Care must betaken to remove all fines or doughy area on therefractory model. The base of the refractorymodel should be at least 1/2" (13 mm) at itsthinnest point. In addition, the base shouldhave angled undercuts between 70° and 80° toprovide for mechanical locking of the modelduring the investing process.

Eliminate any dust or build up caused by grinding, with gentle pressure from an airsyringe or gentle running water. Refrain from theuse of high water pressure or brushing as thismay cause erosion of the master model. Cleanout the small end of the sprue hole with a smalltapered instrument and round-off all sharpedges on the refractory model. Use gentlestream of air to eliminate all loose particles ofinvestment and debris from the refractorymodel. If there are fractured areas around thesprue hole, they should be smoothed to pre-vent loose particles of investment from beingcarried into the cavity during the castingprocess. These areas may be further smoothedby using a small flexible paint brush, paintingthe jagged edges with paint-on investment.Allow the paint-on to air dry at least 5-7 minutesbefore placing the refractory model into theModel Drying Oven.

Place the trimmed model in a Model DryingOven at 450°F (232°C) for 1 hour.


Remove the refractory model from the oven andcompletely submerge in Rosin Dip for approxi-mately 3-5 seconds. The Rosin Dip should be ata temperature of 250°F (121°C).


Investing

Open a jar of well mixed Niranium PrecoatPaint-On or Green Paint-On Investment andpour liquid investment into a bowl. Apply liquidinvestment with a brush, covering the entirewax-up, including the sprues. Holding modelfirmly in hand shake off the excess investment,leaving a thin film of investment on the wax-up.The Niranium Precoat Paint-On or Green LiquidPaint-On Investment should be allowed to dry 7 minutes prior to pouring the outer investment.NobilCoat paint on investment may also beused in this process. Allow the investment todry for 15 minutes then attach the paintedmodel the base of the casting ring with hot wax. Mix Yellow Stripe Investment and prepared liq-uid in a bowl to the following proportions:

Small Ring: 550 Gm Powder to 90 cc LiquidLarge Ring: 640 Gm Powder to 105 cc Liquid

Vibrate the mixture into investment ring andallow 10-20 minutes of moderate vibration. Pourliquid off the top and remove from the vibrator.

Place the ring on the bench and allow it to setan additional 15-25 minutes.

Note: The normal setting time for the initialset is 15-20 minutes. This time may be altereddepending on the temperature of the liquidand room temperature. The warmer the liquid

2929


and environment, the faster the set-time. Thecooler the liquid and the environment , the slowerthe set-time.

Deflask the invested ring and eliminate thefines at the top of the ring by grinding. (Thedoughy area is caused by the settling of the heavier andthe finer particles rising to the top along with the liquid,while vibrating.)

The invested ring must be allowed to benchset for a total of 1 hour prior to its introductioninto a warm furnace. The ring should not beallowed to air dry on the bench longer than 2hours. This longer air drying may cause crackingof the ring once the burnout begins. For casesrequiring a longer time on the bench or out ofthe furnace, should be placed in a humidifiedstate. Either a closed plastic bag with moist towels or similar closed, moist container can be used.

Burnout

Place the investment mold in a warm furnace . Ifit is a gas furnace with a pilot light, the tempera-ture of the furnace should be about 200°F(93°C). This warm temperature prevents thecracking of rings when a ringless technique isused. Increase the furnace temperature slowlyto desired temperatures. Set furnace at 700°F(371°C) and hold for 30 minutes. This will insuredry rings and complete burnout of wax. Raisethe temperature to 1850°F (1010°C) and heatsoak for 30 minutes after reaching this tempera-ture. Cases are ready to cast.

Bench cool the castings 45 minutes to 1 hourbefore devesting.


3030

WELDING

Chrome-cobalt frameworks may be repaired or added onto by welding. The alloy may besoldered, however, welding produces the bestresults.

The area to be welded should be prepared byeither sand blasting or roughing the areas withan abrasive stone, especially if the frameworkhas been high-shined. If sandblasting is utilized,make sure all the grit from the sand is removedwith air pressure, ultrasonic or under runningwater, prior to investing. Any grit remaining maycause pits and other imperfections in the final weldjoint.

Frameworks being repaired or having partsadded must have the parts to be welded, lutedinto position and further secured by partiallyinvesting the framework and its parts in a gypsumproduct or an oxy-phosphate investment.

Note: For best results, if wax is used to lute theparts together, the wax should be eliminatedwith steam or boiling water, ensuring no residueremains.

Thicker areas to be welded should be ground toa “V” shape so that the top surface of the repairor weld area is wider than the bottom.

Adjust gauges to 1 pound oxygen and 1 pound acetylene.

The torch tip should be small. Light the torchand adjust the neutral flame with about 1/2" (13 mm) of blue cone extending from the tip of the torch.

Heat the end of the welding rod to a dull orangeand dip the rod into the powdered flux. Heatboth parts of the area being welded and bringto an even cherry red color. Keep flame in con-tact with the framework/weld area, bring thewelding rod between the parts to be weldedand proceed to melt.

Keep the torch about 1/2" (13 mm) from thearea being welded.

The framework may be finished and polishedusing the wheels, stones, rubber abrasives andpolishes of choice.

3311


Framework Luted Together and Ready for Welding

TROUBLE SHOOTING

REFRACTORY MODELS

Problem: Bubbles in the hydrocolloid impression.

Cause:Master model is not allowed to soakproperly to remove all air. Model should beallowed to soak at least 30 minutes in warmwater prior to duplication.

Cause: Hydrocolloid is too cold when poured.Adjust the pour temperature to 130°F (54°C).

Problem: Refractory model too soft.

Cause: Liquid is too cold. Investment is settingtoo slowly. Liquid should be 70°F (21°C) toallow for the proper setting time of the invest-ment – keep in mind that humidity may alsoaffect the setting time.

Cause: Hydrocolloid material may be too cold.The material should not be allowed to chill in arefrigerator or ice bath. The temperature of thewater bath should be 55°-70°F (13°-21°C).

Cause:Model removed from the hydro-colloidprematurely – allow 55 minutes setting timefrom pouring to recovering the refractory model.

Problem: Too soft after dipping.

Cause: Temperature of the drying oven or dip istoo cold. The refractory model should beallowed to dehydrate 1 hour in a model dryingoven at a temperature of 450°F (232°C). Rosindip should be at a temperature of 250°F (121°C)and the refractory dipped for 5 seconds.

Problem: Plastic patterns will not adhere to model.

Cause: Tackyfier is too thin.

Cause: Tackyfier is not allowed to dry sufficiently.

Cause: Refractory model is too cold.

MOLDS

Problem: Investment cracking.

Cause: Investment taking too long to set-up onvibrator. Investment should take 15-25 minutesto reach its initial set. Humidity may effect thesetting time.

Cause: Liquid is too cold. Remove liquid fromrefrigerator at least 1 hour prior to usage. Idealtemperature for liquid is 70°F (21°C).

Cause: Liquid is not accurately measuredand/or improperly mixed.

Cause: Investment setting too rapidly. Liquidmay not have cooled to room temperature.Improper ratios and/or mixing of liquids.

Cause: Liquid is too warm. When removed fromrefrigerator, do not allow to sit in an overly warmenvironment for extended periods of time.Ideal temperature of liquid is 70°F (21°C).

Cause: Lack of good vibration. Check the vibra-tion of the cases when setting. If liquid at thetop of the case begins to dance and peak, thereis too much vibration. Vibrator should then beturned down until this condition disappears andbubbles begin to rise to the surface.

Cause: Drying ring extenders. Dip extendersinto wax to seal all pours, preventing liquidfrom being absorbed into the extender andweakening the investment. This type of crack-ing, left unchecked, will allow the cracking tocontinue into the main body of the investedring.

Cause: Investment is too thick when pouring theouter ring. Check the liquid to powder ratio rec-ommended by the manufacturer (the mixtureshould be grainy – the consistency of oatmeal).

Note: If there is a thick crust atop the investedring, the mix is too loose. The crust should bebetween 1/8” and 1/4” (3-6 mm) thick, 1/8” (3mm) being better. If the crust is less than 1/8” (3 mm), the mixture is too thick.


3232

Cause: Improper removal of the crust once theinvestment has set. If the complete layer ofcrust is not removed, the cracking formed in thecrust may extend into the main body of thecasting ring, causing internal cracking in themold or fins in the casting.

Cause: Case allowed to bench set too longbefore the crust is removed.

Cause: Refractory models not properly dehy-drated. Allow the refractory models to dehy-drate 1 hour at 450°F (232°C) prior to rosin dip-ping.

Problem: Thermal cracking.

Cause: Oven run up too fast on low fire. Burnoutis important! Temperature should rise fromroom temperature to 700°F (371°C) in 1 hour.From 700°F (371°C) to reaching mature tempera-ture should take approximately 1 to 1-1/4 hoursand then be allowed to heat soak for an addi-tional 30 minutes. The longer the heat soak, thegreater the expansion. (Tighter fits = less time.)This soak time is especially crucial for palatalcastings as this also hardens the investment.

Cause: Case left too long on the bench afterinvesting or overnight. Cases should be placedin the furnace within 3 hours of investing andtrimming. Should the period be longer beforeplacing into a warm furnace, the cases must berefrigerated or placed in a humidified state(plastic bag and moist towel) until ready to beintroduced into the furnace. Cases may beplaced in the oven in the plastic bag along withthe moist towel.

Cause: Furnace not warm when the cases areloaded. Make sure invested cases are placedinto a warm furnace at about 200°F (93°C). Ifyour oven does not possess this capability, thecases must be placed in a plastic bag with amoist towel if burnout cycle is not started within3 hours of pouring investment.

Cause: Outer investment layer is too thin at theouter wall. The pattern or model must be at least1/4” (6 mm) from the outer wall of the investment.

Cause: Sharp angles or corners on the refractorymodels.

Cause: Stacking rings in the oven improperly.Make sure the rings are layered and staggered.

Cause: Improper mixing of the liquids.

Cause: Improper mixing ratio of liquid toinvestment.

Cause: Not enough vibration to eliminate theproper amount of liquid from the investment asit sets. Moderate vibration is required. Vibrationshould continue until the investment reaches itsinitial set, 20 minutes.

Cause: Low-fire burnout not long enough tothoroughly dry models and eliminate wax com-pletely, causing pressure or steam buildupinside the ring. Low-fire burnout is 400°- 500°F(204°-260°C), holding for 1 hour.

Cause: Blower activated prematurely. Blowermust not be turned on prior to molds beingcompletely dry and plastic and wax is eliminat-ed. This type of cracking is likely to be seen asfins.

CASTINGS

Problem: Pits in the castings.

Cause: Sprue connections are too large.Check for tapered connections where the sprueconnects to the wax-up. If sprue connections aregood, consider using a reservoir.

Cause: Sprues are too large. Use 8 gauge, roundsprues with tapered connections.

Cause: Case placed in the casting machineincorrectly. Make sure the case is placed in the casting machine with themain sprue(s) in the direction of rotation.

Cause: Trash carried into the case with moltenmetal. Make sure the sprue hole is free fromdebris before placing in the oven. Also, upon


3333

removal from the oven just prior to casting,remove the case from the oven and gently taptongs while the case is secure in tongs. Makesure the sprue hole is facing down when remov-ing any loose investment from the sprue hole.

Cause: Trash in the crucible. Check crucible forscraps of old or burnt alloy. Also, examine thecrucible for pitting, cracking or other defects.

Cause: Imperfections in the sprue hole. Checkto see if there are bubbles or rough surfaces inthe sprue hole or the refractory model beforedehydrating and rosin dipping. Smooth anyrough surfaces of the sprue hole once removedfrom the hydrocolloid. After opening the holewith a round instrument, coat the roughenedareas with Nobilium Green Paint-On, NobilCoator Niranium Pre-Coat and let dry prior to dipping.

Cause: Dirty rosin dip. The rosin pot should becleaned periodically. Debris and investment parti-cles from the refractory models tend to settle inthe rosin dip and may become stirred andadhere to the freshly dipped model.

Cause: Thin areas of investment. Take care inthe investing process as well as with the refrac-tory models not to create thin slivers or sharp,thin angles in the investment.

Problem: Bubbles on the surface of the castings.

Cause: Green Paint-On, NobilCoat or NiraniumPrecoat applied too thickly.

Cause: Paint-on investment not allowed to dryproperly – must set at least 15 minutes prior topouring investment. Check manufacturer’s rec-ommendations.

Cause: Paint-on investment allowed to dry toolong. Prolonged bench-set of the paint-on willproduce cracking and rough geographic castings.

Cause: Premature removal of refractory modelfrom hydrocolloid. Allow 55 minutes set-time frompouring to recovery of refractory model.

Cause: Debubblelizer not allowed to properlydry.

Problem: Short castings – clasp and retention areas notcompletely cast.

Cause: Case not completely burned out, carbonresidue remaining in the mold.

Cause: Insufficient turns on a spring driven cast-ing machine.

Cause: Toomuch time melting the alloy. Outsideof mold cooled too much prior to casting.

Cause: Placed in the casting machine improper-ly. Check the direction of rotation in relation tosprues.

Cause: Not enough alloy.

Cause: Alloy temperature too cold. Make surethe alloy is properly melted. Check the meltprocedure for the type of casting machine ortorch used.

Problem: Short castings – clasp and retention cast com-plete but bars are shortcast/holes in the horseshoe palate.

Cause: Alloy not molten enough.

Cause: Not enough heat-soak. After furnacereaches mature temperature, heat-soak at thattemperature for a minimum of 30 minutes prior tocasting.

Cause: Alloy too cold. If some alloy remains inthe crucible, metal was not completely melted.

Problem: Brittle clasps.

Cause: Torch not adjusted properly – too muchacetylene.

Cause: Alloy overheated.

Cause:Metal fatigue. Alloy cast or melted toomany times without replenishing with 50% newalloy.


3434

Problem: Sloppy hinges.

Cause: Too much paint-on investment or notpainted on properly.

Cause:Metal too hot.

Cause: Improper metal oxidation during theburnout procedure. These cases should beamong the first to be cast. Heat-soak no longer than20 minutes. The normal heat-soak is 30 minutes,however, with hinges keep as much oxidation aspossible, therefore the lower soak time.

Problem: Porosity in casting.

Cause: Buttons porous and spongy, usuallyindicative of alloy being overheated.

Cause: Porosity at junction of casting andsprues. Sprues not large enough. Use largerdiameter sprue or sprue with reservoir.

Problem: Fins on sprues.

Cause:Weak investment. Check the liquid mix-ing ratio as well as the liquid/powder ratio.

Cause: Cases introduced into the oven too soon.Invested rings must be allowed to cure 1 hourprior to being placed in a warm oven.

Problem: Internal fins on castings.

Cause: Not enough vibration when investing.The invested ring must have sufficient vibrationto allow the proper amount of liquid to escape.

Problem: Fins around the clasps, mesh and borders ofthe castings.

Cause: Too much tackyfier.

Cause: Excessive wax used in sealing down thepatterns.

Cause: Rosin dip not absorbed by the refractorymodel – model too cold when dipped. Refrac-tory model should be allowed to dehydrate 1 hourin a Model Drying Oven at a temperature of

450°F (232°C). The rosin dip should be at 250°F(121°C) and refractory model dipped for 5 seconds.


3535

I M P O R T A N TPROCEDURES & PRECAUTIONSFOR PROCESSING NOBILIUM

PARTIAL DENTURES

1) Adequate local exhaust ventilationshould be provided for all operations suchas grinding, polishing and finishing. Goodindustrial hygiene practices will eliminateany possible hazard from dust created byinvestments, grinding wheels, sandblasters,alloys, etc.

2) Adequate general ventilation should be provided to all laboratory areas.

3) Dust removal from clothing and cleaningmachinery should be accomplished bypower suction methods, not by air hoses.

4) Every employee should be appraised ofthese recommendations.

5) Dental laboratories, like all other industries, must conform to OSHA regulations.Obtain a copy of all applicable standards asissued and conduct regular inspections toinsure your laboratory is properly equippedand that all OSHA requirements areobserved at all times.

BIBLIOGRAPHY

Air Force Pamphlet 162-6: Dental LaboratoryTechnology, Removable Prosthodontics, UnitedStates Air Force, Washington, DC., 1991, U.S.Government Printing Office.

Grasso, Joseph E. & Miller, Ernest L.: RemovablePartial Prosthodontics, Third Edition, St Louis,Missouri, 1991, Mosby Yearbook Inc., B.C.Decker.

McGivney, Glen P. & Castleberry, Dwight J.:McCraken’s Removable Partial Prosthodontics,Eighth Edition, St Louis, Missouri 1989, The C.V.Mosby Company

Rudd, Kenneth D., Morrow, Robert M. & Rhoads,John E. : Dental Laboratory Procedures,Removable Partial Dentures, Volume Three,Second Edition St Louis, Missouri, 1986, TheC.V. Mosby Company.

United States Navy Training Manual NAVEDTRA10679: Dental Laboratory Technology, UnitedStates Navy, Washington, DC., 1979, U.S.Government Printing Office.

Stratton, Russell J./Wiebelt, Frank J.: An Atlas ofRemovable Partial Dentures Design,Quintessence Publishing Co., Inc. Chicago, IL.,1988, Quintessence Publishing Co., Inc.


3636


3737

ILLUSTRATED DENTAL TERMS

BARS

SADDLES CLASPS BOXINGS

PONTICS

ONLAY

MISCELLANEOUS RETAINERS

STRESS RELIEVINGATTACHMENTS

PRECISION ATTACHMENTS

BACKINGS

Lingual Apron Horseshoe Rugae Patatal Circular

Open Type (Full Finishing Line)

Open Type (No Finishing Line)

Porcelain Tooth / Plastic DummyPorcelain Facing

Pin Facing

Trupontic

Plastic Veneer

Milled

Hinge

Prefabricated

MetalOcclusal

ReinforcingMesh

StrengthBars

UniversalMovement

ControlMovement

w/Facing

SolidMetal

PlasticVeneer

Solid (w/Extension)

Solid (w/o Extension)

Equi-Poise

Double

Akers

Roach

Arm Only

Rest &Upright

Indirect

Direct

EmbrasureHook

Rest


3838

° F °C

500 260510 266520 271530 277540 282550 288560 293570 299580 304590 310600 316610 321620 327630 332640 338650 343660 349670 354680 360690 366700 371710 377720 382730 388740 393750 399760 404770 410780 416790 421

° F °C

800 427810 432820 438830 443840 449850 454860 460870 466880 471890 477900 482910 488920 493930 499940 504950 510960 516970 521980 527990 5321000 5381010 5431020 5491030 5541040 5601050 5661060 5711070 5771080 5821090 588

° F °C

1100 5921110 5991120 6041130 6101140 6161150 6211160 6271170 6321180 6381190 6431200 6491210 6541220 6601230 6661240 6711250 6771260 6821270 6881280 6931290 6991300 7041310 7101320 7161330 7211340 7271350 7321360 7381370 7431380 7491390 754

° F °C

1400 7601410 7661420 7711430 7771440 7821450 7881460 7931470 7991480 8041490 8101500 8161510 8211520 8271530 8321540 8381550 8431560 8491570 8541580 8601590 8661600 8711610 8771620 8821630 8881640 8931650 8991660 9041670 9101680 9161690 921

° F °C

1700 9271710 9321720 9381730 9431740 9491750 9541760 9601770 9661780 9711790 9771800 9821810 9881820 9931830 9991840 10041850 10101860 10161870 10211880 10271890 10321900 10381910 10431920 10491930 10541940 10601950 10661960 10711970 10771980 10821990 1088

° F °C

2000 10932010 10992020 11042030 11102040 11162050 11212060 11272070 11322080 11382090 11432100 11492110 11542120 11602130 11662140 11712150 11772160 11822170 11882180 11932190 11992200 12012300 12602400 13162500 13712600 14272700 14822800 15382900 15933000 1649

1 Troy DWT = 1.555 Grams

1 Troy Ounce = 1.097 Ounces

1 Troy Ounce = 31.1 Grams

1 Ounce = 28.35 Grams

1 Gram = .643 Troy DWT

1 Gram = .03528 Ounces

1 Kilogram = 35.28 Ounces

1 Kilogram = 2.205 Pounds

1 Fluid Ounce = 29.57 Cubic Centimeters

1 Pint = 473.2 Cubic Centimeters

1 Pint = 16 Fluid Ounces

1 Quart = 946.2 Cubic Centimeters

1 Gallon = 128 Fluid Ounces

1 Gallon = 3.785 Liters

1 Liter = 1.057 Quarts

1 Liter = .2642 Gallons

WEIGHT VOLUME

CONVERSION TABLESTEMPERATURE °F/°C


3939

N O T E S


4040

N O T E S

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