TROUBLESHOOTING GUIDE

► ALLOYS► SOLDERING► INVESTMENT► PORCELAIN

THE ARGEN CORPORATION

ALLOYS TABLE OF CONTENTS PAGE

1. Porosity……………………………………………………………….1-22. Brittle Castings………………………………………………………. 2-33. Hot Tears………………………………………………………………34. Rough Casting…………………………………………………………3-45. Suckback………………………………………………………………46. Rounded Margins……………………………………………………. 47. Incomplete Castings……………………………………………………58. Pattern Failed to Cast…………………………………………………59. Pits in Casting…………………………………………………………5-610. Bubbles or Nodules on Casting……………………………………… 611. Investment Particles in Casting……………………………………… 612. Inconsistent Oxide Appearance………………………………………613. Warpage………………………………………………………………7-814. Allow Tarnishing………………………………………………………8-9

SOLDERING

1. Solder Fails to Flow…………………………………………………. 9-112. Accidental Melting of Parent Metal…………………………………. 113. Fractured Soldered Connection…………………………………….... 11-124. Solder Joint Sag………………………………………………………125. Solder Joint Contaminated……………………………………………126. Warpage During Soldering Procedure…………………………………13

INVESTMENT

1. Investment Sets too Rapidly………………………………………….132. Investment Sets too Slowly……………………………………………143. Inconsistent Thickness of Mix…………………………………………144. Investment Mold Cracks During Burnout…………………………… 14-155. Too Much or Too Little Expansion……………………………………15

PORCELAIN

1. Bubbling of Opaque……………………………………………………15-162. Cracks in Opaque………………………………………………………173. Porcelain Bubbles………………………………………………………174. Checks, Cracks and Crazing………………………………………… 17-185. Discoloration………………………………………………………… 18-196. Milky or Chalky Appearance…………………………………………197. Insufficient Glaze………………………………………………………198. Porcelain Bond Failure……………………………………………….19-20

CHARTSTemperature Conversion Table (ºF) (ºC)DWT - Gram - OZ Conversion

ALLOY TROUBLESHOOTING

PROBLEM SOLUTION

1. POROSITY

a. Gasses Trapped In Mold Provide a maximum of 1/4” of investment over pattern and minimum 1/4" from sides of ring. If necessary, the height of the sprue former may be adjusted to position wax pattern to proper height. Remove the glaze on the top of the ring to create a porous surface on the investment to allow gas to escape.

b. Insufficient Sprue The indirect method of spruing is recommended for both single and multiple units.1) 8 - 10 gauge ingate (from runner bar to pattern) sprues with an approximate length between 2mm and 4mm should be used, depending on pattern size.2) 4 - 6 gauge runner bars should span the length of bridge. If runner bar conforms to arch shape, relieve stress by cutting and reconnecting in sections.3) Connect 8 - 10 gauge feeder sprues to bottom of runner bar long enough to allow placement of runner bar in the heat center of the ring.Note: Position the runner bar in the heat center of the ring, and wax patterns outside the heat center. The runner bar will serve as the reservoir supplying molten alloy to castings allowing proper order of solidification to take place.

If the direct spruing method is utilized, connect an 8-10 gauge sprue to the thickest portion of the wax pattern. Pontics and larger units may require (2) 8-gauge sprues. Reservoirs are placed 1.5mm (1/16”) from the wax pattern.

c. Overheated Mold Calibrate burnout furnace. Elevated temperatures can interfere with alloy solidification and cooling, affecting casting density. Follow alloy’s recommended burnout temperature.

d. Under Heated Mold If mold burnout temperature is too low, the pattern (especially plastic), may not burn out completely.

e. Overheated Alloy Overheating increases gas inclusions, carbon absorption and oxidation of low melting temperature alloy components.

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PROBLEM SOLUTION

f. Wax Contains Dirt If the wax is noticeably dirty, change the wax in the wax pot. Foreign debris will not burn out and will become incorporated in the casting.

g. Turbulence Ensure that casting arm is balanced.

2. BRITTLE CASTINGS

a. Overheating Alloy When Casting An alloy’s physical properties will change (especially high palladium alloys) when overheated. Follow alloy manufacturer’s instruction for proper propane or gas/oxygen ratios to achieve proper flame and proper appearance of alloy when ready to cast.

b. Failure To Add New Alloy To Existing Sprues, Buttons, Etc.

When recasting alloy buttons, 30% - 50% new alloy must be added to restore the original physical properties of that alloy. All alloys must be absolutely clean i.e.: free of investment, oil, blasting materials.

c. Overheated Mold Overheated molds may increase grain growth during cooling, thereby increasing the chance for hot tearing and brittleness. Use the alloys recommended burnout temperature.

d. Alloy Contamination Contamination may change the physical properties of an alloy. Avoid cross contamination by using crucibles, stones, and burs on one alloy only. Cross contamination will cause alloy and porcelain to react in an unpredictable manner.

e. Quenching Too Soon After Casting Be careful not to quench the alloy too soon after casting. You may only quench crown & bridge gold alloys. Never quench ceramic alloys.

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PROBLEM SOLUTION

f. Carbon Inclusion Adjust fuel mixtures to proper flame (See page 2 #2-a ). Carbon is major cause of brittleness. Carbon contributors include investment, incomplete wax elimination, improper torch adjustment (especially gas rich flames). Palladium based alloys are particularly sensitive to carbon. Non-carbon investments are recommended for these alloys. Carbon inclusion also increases the risk of porcelain bubbling which may be the first sign that carbon exists in the casting.

3. HOT TEARS

a. Brittle Castings See page 2 - #2

b. Quick Stops Never manually stop casting machine from spinning. Natural slowing maintains centrifugal pressure, resulting in proper grain growth. Grain size is directly implicated in hot tearing; some alloys will tear more easily when large grains form.

c. Quenching Quenching is not recommended for ceramic alloys.

d. Overheated Mold See page 2 #2-C

e. No New Alloy Added To Existing Buttons When Recasting

When casting existing buttons, sprues, etc., 30% - 50% new alloy must be added to restore the physical properties of the alloy. This is especially true of ceramic alloys.

4. ROUGH CASTING

a. Wax Pattern Cleaner Not Dry Remove all excess wax pattern cleaner with a gentle stream of air. Wax pattern and sprue former base must be totally dry prior to investing.

b. Overheated Mold Calibrate burnout oven and use recommended burnout temperature for alloy being cast. Overheated mold may cause investment breakdown.

c. Investment Not Completely Set Allow investment to bench set thoroughly before starting burnout procedure.

d. Outdated Investment Outdated investment may break down during the burnout procedure. Check expiration date.

e. Overheated Alloy Overheated alloy during melting may cause investment breakdown.

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PROBLEM SOLUTION

f. Excessive Casting Force Use of too much casting force may cause rough castings. The recommended amount of turns on your centrifugal casting machine is the following:

High Noble: 2½ - 3 turnsNoble: 3 turnsPredominately Base: 4 turns

g. Solid Plastic Sprues Solid plastic sprues cause excessive pressure in mold when plastic expands during burnout. If plastic sprues are required coat plastic sprues with wax before investing.

h. Die Lubricant Oily die lubricant on pattern creating surface tension.

i. Excessive Vibration Use minimal vibration during investing.

5. SUCKBACK

a. Overheated Alloy Properly adjust torch flame (see page 2 - #2-a ) and melting time to reduce casting temperature of alloy.

b. Over Generous Button Wax pattern should be weighed prior to investing by using the following formula; wax pattern x density = alloy amounts . By using this formula, casting buttons will be kept to a minimum.

c. Spruing Utilize the indirect sprue technique.

6. ROUNDED MARGINS

a. Under Heated Alloy Metal must be fluid and approximately 150º-175º F (66º-79ºC) above the melting range when cast. Check alloy manufactures recommendations for proper casting temperatures.

b. Under Heated Mold Utilize alloys recommended burnout temperature. An under heated mold will cause alloy to solidify prematurely.

c. Gasses Trapped In Mold See page 1 #1-a

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PROBLEM SOLUTION

d. Improper Placement Of Ring In Cradle

Trailing edge casting techniques must be followed. Ring should be placed so that the trailing edge (margins) of the wax pattern face the opposite direction of the rotation of the arm of the casting machine. This insures the flow of molten alloy toward the trailing edges preventing miscasts.

7. INCOMPLETE CASTINGS

a. Insufficient Burnout Check oven calibration. Always provide a minimum 1 hour heat soak. Add 10 minutes for each additional ring in the oven.

b. Spruing Technique See page 1 #1-b

c. Insufficient Thickness Of Wax/Plastic Patterns

An average thickness of at least 0.3 – 0.4 mm must be maintained to achieve a complete casting. Utilize a wax gauge when in doubt.

d. Insufficient Casting Force Check centrifugal casting arm spring. Give extra wind for low density alloys. Check balance. Turbulence may slow alloy entry into the casting ring.

e. Under Heated Alloy See page 4 #6-a

f. Gasses Trapped In Mold See page 1 #1-a

g. Improper Amount Of Alloy Used Weigh wax pattern and sprues (as described in page 4 #5b) to determine adequate amount of alloy required to achieve a complete casting.

8. PATTERN FAILED TO CAST

a. Pattern Separated From Sprue During Investing (Floaters)

Reinforce pattern and sprue with a drop of sticky wax. Avoid vigorous vibration during investing procedure.

9. PITS IN CASTING

a. Overheated Mold Check alloy’s recommended burnout temperature. A temperature that is too high will cause the alloy to improperly solidify.

b. Investment Particles In Castings See page 6 #11- a,b,c,d

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PROBLEM SOLUTION

c. Dirty Wax Place a cover on your wax pot when not in use to avoid getting dust, metal, grindings, etc. in the wax. These do not burn out with the wax. Avoid any grinding (finishing) in waxing area of laboratory.

d. Overheated Alloy See page 1 #1-e

e. Excess Investment And Debris Exist On Buttons

Each piece of used alloy should be examined and cleaned. Insure all investment has been removed prior to remelting.

10. BUBBLES OR NODULES ON CASTING

a. Investment Was Poured Too Fast Pour the investment into the ring slowly (do not dump it on the wax pattern) to avoid entrapment of air pockets.

b. Surface Tension Reducer Was Not Used On Wax Pattern

Apply Wax Pattern Cleaner (debubblizer) and completely blow dry pattern surface and sprue former base with a gentle stream off air prior to investing.

c. Excessive Vibration During Investing Procedure

Too much vibration may create bubbles while pouring investment.

d. Die Lubricant Excessive oil from die separator on pattern.

e. Tiny, Perfectly Round Nodules (May Look Like Retention Beads)

Extend mixing time to 15 sec. under full vacuum without paddle turning. This will allow the gases that form by mixing special liquid with the investment, to be vacuumed out of the mix.

f. Vacuum Insufficient Or Absent Check vacuum mixer to ensure full vacuum is being drawn.

11. INVESTMENT PARTICLES IN CASTING

a. Sharp 90% Edges And Corners At Sprue / Wax Pattern Junction

Attach sprues to wax pattern with flared edges. During casting sharp corners may flake off with the force of the molten metal “shooting” into the casting ring (mold).

b. Sprue Hole And/Or Sprue Base Has A Roughened Surface

Avoid any scraping around the sprue hole leads. If the investment surface is scraped initial set up, a rough surface is created on the investment producing, in turn loose particles that may mix in wit molten metal. Also, wait 30 minutes before removing sprue former from newly invested ring.

c. Remnants Of Previously Mixed Investment Was Left In Casting Ring

Be certain that investment rings are thoroughly cleaned prior to adding newly mixed investment.

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PROBLEM SOLUTION

d. Burnout Temperature Too High Assure that burn out temperature does not exceed the maximum temperature allowed by investment manufacturer.

12. INCONSISTENT OXIDE APPEARANCE (AFTER DEGASSING)

a. Contaminated Stones Do not cross contaminate finishing stones. Keep stones separated for different alloys.

b. Oil Or Debris On Alloy Handle finished casting with tweezers only during blasting and following cleaning and oxidation cycles. Oil from finger tips may easily be transferred to metal surface. These oils will not always burn off during oxidation cycles and will cause patchy appearance or unusual oxide color.

c. Long Or Short Oxidation Cycle Always use the recommended oxidation (degassing) cycle for the alloy. Different alloys (even those with similar composition) may oxidize very differently. Not following the recommended cycle may increase the risk of porcelain discoloration and/or greening. Technique changes may also decrease porcelain-to-metal bond strength.

d. Acid Treatment Acids will deplete the minor compositional elements near the surface that are responsible for the oxide. Longer oxidation cycles (rather than higher temperature treatments) will usually replace these elements and form the proper oxide color. Failure to obtain the proper oxide may decrease bond strength. After using acid rinse thoroughly, dry, refinish surface with recommended stones, clean ultrasonically, and then proceed with oxidation (degassing) cycle.

e. Recast Alloy See page 2 #2-b

13. WARPAGE (MULTI-UNIT BRIDGES)

a. Removing Wax-Pattern Without Reseating It

The wax pattern must not remain off the dies for any extended length of time (especially in warm, humid climates). A time period of no longer than 20 minutes should pass between final wax adjustments to investing. Replace the wax pattern on the die to insure against any problems with the memory of the wax.

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PROBLEM SOLUTION

b. Utilize A Secure (Non – Rocking) Double Pin System For Model Work

Be certain that the individual sectioned dies are secure and non – rocking. If the dies are easily removable from the model with your fingers, chances are the dies are not adequately secure in the base. You should be forced to loosen the dies by pressing the pin underneath the model (fig A), then remove the dies manually with your fingers (fig B).

Figure A Figure B

c. Failing To Section Bridge Before Spruing

Before spruing, let the bridge cool down on the model. Next, using wax separating filament or nylon fishing line, cut one joint to every 4 units to relax the inherent stresses of the wax. Then reattach the bridge as desired using dead soft wax.

d. Undercuts Not Blocked Out Properly If necessary, use a survey to determine the location of all undesirable undercuts on the die.

e. Interproximal ConnectorsToo Thin Be certain that interproximal connectors of multiple unit splints are of adequate thickness strength is derived from the incisogingival dimension.

f. Wax Properties Exhausted When using wax pots to melt your wax, the daily heating and cooling of wax in the pot will exhaust the properties of the wax, which allows wax to maintain it’s accuracy. Replace the wax in the pot with new wax approximately once every month.

g. Inadequate Support Avoid warpage in vacuum porcelain furnace by using adequate support when ever possible. Support all abutments with firing pins during firing.

14. ALLOY TARNISHING

a. Porosity Microscopic surface porosity may not only entrap finishing materials but also food particles. This will produce bacteria intraorally which will oxidize the casting’s surface causing it to discolor. Avoid porosity by using proper spruing techniques. (See page 1 - #1 )

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PROBLEM SOLUTION

b. Acidity Of Salvia And Certain Medications

Depending on chemical nature of patient’s physiology, certain medications, where nitroglycerine (heart medication) enzymes are present, may have an influence in tarnishing, as will a high acidity content of the saliva in the oral environment.

c. Copper Saturated Acid When high content copper alloys are pickled in hydrochloric acid, the acid should be changed often. A casting that is pickled in copper saturated (green color) acid will transfer that copper to the casting, later causing tarnishing.

d. Sulfur Contamination High levels of sulfur may be present in water (well water) causing a casting to tarnish.

e. Galvanic Reaction The use of two dissimilar metals in the mouth may cause an electrical (galvanic) reaction. Avoid the combination of gold alloys and mercury/amalgam/silver fillings coming in direct contact with each other.

SOLDER TROUBLESHOOTING

1. SOLDER FAILS TO FLOW

a. Oxide Build-Up On Parent Metal Certain alloys (especially high palladium content alloys) produce a heavier oxide than others. A heavy oxide on the surfact of the parent metal will act as a deterrent between the solder and the metal, preventing good flow. Lightly flux the area to be soldered with the recommended flux to reduce oxidation and improve solder flow. To avoid oxides from forming on the alloy, do not exceed a temperature of 900ºF (482ºC) when preheating invested case in a burnout oven. Extreme caution should be exercised when applying flux to PTM alloys. Utilizing too much flux may cause porcelain contamination.

b. Oxidation Of Solder It is possible for solder to produce an oxide prior to soldering which may affect its flow qualities. To avoid this, lightly coat the solder with paste flux. Introduce the solder when the abutment joints exhibit a light yellow/red color.

c. Parent Metal Too Cold The melting temperature of the parent metal must be higher than the flow point of the solder or flow will not take place. The heat projected from the parent metal is used to melt the solder not the direct heat from the flame. The solder area should have a light yellow/red appearance when ready to accept the solder.

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PROBLEM SOLUTION

d. Rough Solder Joint It is not necessary to roughen the area to be soldered with stones or cut grooves with a disk to create retention for proper bonding of the solder. It is recommended to utilize a silicone-free rubber wheel. Then, lightly sand blast the joint with 50 micron aluminous oxide with no more than 30 pounds (2 bar) air pressure. A liquid in a slightly etched surface will wet better. Ultrasonically clean in distilled water for 10 minutes. The joining of solder and parent metal does not depend on mechanical retention for a bond, but rather a chemical, metallurgical bond.

e. Solder Gap Too Narrow The correct space will allow capillary action to occur. Too narrow a solder joint will prevent adequate flow of solder. An average gap of approximately .3mm (business card thickness) is recommended. Both surfaces must be parallel as possible. (See diagrams below ).

f. Units To Be Soldered Are Covered With Too Much Investment

Investment should be mixed thick enough so that the units do not sink too far into investment mounds. If units to be soldered are covered with too much investment, the flame will be prevented from naturally passing through the area to be soldered, preventing adequate heating and solder flow.

g. Not Using Distilled Water When Mixing Investment

Tap water may contain unsuspecting chemicals that may contaminate soldering investment which (in turn) may contaminate the soldering area. Use distilled water to insure purity.

h. Investment Patty Too Thick Investment patty should be limited to a height of no more than 10 mm to avoid drawing heat from the solder joint. Trim patty with model trimmer accordingly. (See diagram below ).

0.25 0.25 -- 0.75mm0.75mm

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PROBLEM SOLUTION

2. ACCIDENTAL MELTING OF PARENT METAL DURING SOLDERING

a. Incorrect Solder Being Used If the flow of the solder is too close to the melting temperature of the parent alloy, the alloy may begin to distort or melt. It is best to use alloy manufacturer’s recommended solder for the alloy you are soldering.

b. Overheating Of Parent Alloy Avoid overheating of parent alloy by gradually brushing the invested units with the flame in a slow circular motion. Then start concentrating the flame on the area to be soldered. Introduce the heat of the flame from one side. When the parent alloy has been reached a light yellow/red color, introduce the solder from the other side. This process should be completed as quickly as possible without removing the flame from the work.

3. FRACTURED SOLDER CONNECTION

a. Improper Connector Design Design of the solder connectors greatly affects the strength and rigidity of the restoration. Contour the connector so it is as thick as possible incisogingivally. The alloy to be soldered should be as close together and as flat as possible with one another. (See page 10 #1-e)

b. Dirt Or Debris In Solder Joint Surface of the parent metal to be soldered must be clean and free of any foreign material.

c. Oxidized Alloy Lightly flux the joint prior to heating. (See page 9 #1-a)

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PROBLEM SOLUTION

d. Overheating Of Solder Overheating the solder by using too hot a flame, or prolonged exposure to flame after solder has flowed, will weaken the solder and produce a porous joint. Once the molten solder has filled the joint, immediately remove the flame directly from the solder joint. Continue to brush the flame over the entire assembly to allow more even cooling of the framework before removing the flame entirely. This technique will allows the assembly to cool more evenly, avoiding less stress.

e. Incorrect Solder For Alloy Use the recommended solder for the alloy. Prescribed solders are designed to work the best with the parent metals.

4. SOLDER JOINT SAG

a. Overheating Solder See above, #3-d

b. Incorrect Solder For Alloy Melting temperature of solder may be too low for future reheating procedures. Use recommended solder for alloy.

c. Unsupported Bridgework Be sure to properly support all abutments, heavy areas and pontics during porcelain firing procedures.

d. Firing Temperature Of Porcelain Exceeds Melting Point Of Solder

Use a porcelain that matures at a lower temperature than the solder being used.

5. SOLDER JOINT CONTAMINATED

a. Over Fluxing When using an excessive amount of flux, the flux may not burn out completely and become trapped in the solder. This will result in a porous joint and cause gassing during porcelain firing procedures. Remove any excess flux that may exist around the soldered joint area by placing it in hydrofluoric acid. Sandblast with non-recycled aluminum oxide, prior to finishing.

b. Improper Use Of Stones, Disks, Etc. Avoid cross contaminating disks and stones. This will transfer contaminating materials to the surfaces being soldering.

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PROBLEM SOLUTION

6. WARPAGE DURING SOLDERING PROCEDURE

a. Sectioned Bridge Inaccurately Splinted Together

A pattern resin with minimal shrinkage properties (i.e.; “G.C. Pattern Resin” or similar) is recommended to securely bond sectioned parts together. This should be done on a solid (not sectioned) model. Optimum accuracy may be achieved by the dentist doing this chair side in the mouth during a try-in-stage.

b. Soldered Restoration Was Quenched Always allow restoration to bench cool after soldering. Quenching produces heat shock which may distort the soldered restoration.

c. Soldered Framework Cooled Unevenly

Once solder has flowed, pull flame back, and lightly brush the flame back and forth over entire bridge to achieve an even temperature. Then pull flame away and allow to bench cool.

d. Solder Joint Gap Too Wide Accurate fit of a restoration may be affected by shrinkage of excessive amounts of solder. Average gap of a solder joint should be .3mm (business card thickness) to keep solder amount and solder shrinkage to a minimum. (See page 10 #1-e )

INVESTMENT TROUBLESHOOTING

1. INVESTMENT SETS TOO RAPIDLY

a. Incorrect Liquid/Powder Ratio Check suggested recommendations of proper liquid/powder ratio for investment being used.

b. Spatulating Too Long Or Too Fast Spatulate according to investment manufacturer’s recommended time and speed.

c. Room Temperature Too Warm (Above 80º F 27ºC)

Store liquid in a cool location. Ideal liquid temperature is 65º F (18ºC.)

a. Presence Of Set Material In Mixing Bowl/On The Mixing Blade

Be certain to clean bowl and blade thoroughly or replace bowl, if necessary.

e. Aged Investment Powder Discard outdated material. Check investment expiration dates.

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PROBLEM SOLUTION

2. INVESTMENT SETS TOO SLOWLY

a. Investment Powder And/Or Liquid Is Too Cold

Do not store powder or liquid in a refrigerator where it will chill liquid too much. Ideal liquid/powder temperature is 65º F (18ºC) - 72ºF (22ºC).

b. Contaminated Mix Avoid contaminants such as alcohol and detergents. Use distilled water only. Use separate mixing bowls for different types of investments. Do not use bowls where gypsum was previously mixed .

c. Insufficient Spatulation Increase spatulation time according to investment manufacturer’s recommendation.

3. INCONSISTENT THICKNESS OF MIX

a. Incorrect Liquid/Powder Ratio Check manufactures directions for recommended liquid/powder ratio for investment being used. Measure and weigh accordingly.

b. Investment Powder Exposed To Humidity

Store investment powder in a cool, dry place.

c. Inconsistent Mix If using bulk investment be sure to mix powder before each use. This will insure good particle dispersion.

4. INVESTMENT MOLD CRACKS DURING BURNOUT

a. Investment Too Dry When Placed In Oven

If ring sets longer than investment manufacturer recommends, soak the ring in water for approximately 5 minutes before placing in a burnout oven. Follow investment technique sheet, or contact manufacturer for specific instructions.

b. Too Many Units In Ring Do not overcrowd ring with too many wax patterns. When too much alloy is cast into the ring, excessive weight of molten alloy may create stress to the investment, causing breakdown or cracking of the mold.

c. Excessive Molten Alloy Force Do not overwind casting machine. Excessive force of alloy may cause mold to fracture. (See Page 4 #4-f)

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PROBLEM SOLUTION

d. Too Rapid Temperature Climb Of Burnout Oven

If not using a fast fire investment, start with a room temperature oven and raise temperature gradually according to investment manufacturer’s instructions. Some investments require a slow temperature climb (for example, 10ºF (-12ºC) per minute) especially when utilizing the ring less technique. Use a two stage burnout technique.

e. Incorrect Investment Water/Powder Ratio

Follow manufacturer’s instruction for proper liquid/water powder ratio.

(Too Much Water May Weaken Investment)

f. Plastic Sprues And/Or Patterns Plastic may require a thin coat of wax to allow for proper expansion. A two-stage burnout is recommended when using plastic sprues and patterns.

g. Investment Not Completely Set Allow investment to set up thoroughly before starting burnout procedure.

h. Too Much Moisture In Ring Proper water/powder ratios must be used. If ring liner is used, shake off excess water to prevent change of water powder ratio.

5. TOO MUCH OR TOO LITTLE EXPANSION

a. Improper Setting Expansion Check water/powder ratio investment. Alloys in different categories require different water/powder ratios. To increase and decrease expansion, check the investment manufacturer’s recommendation.

b. Improper Thermal Expansion Typical soak time should be 45 minutes to 1 hour for 1 ring at end temperature. Add 10 minutes for each additional ring.

PORCELAIN

1. BUBBLING OF OPAQUE

a. Overheated Alloy/Opaque Verify casting temperature and opaque firing temperature.

b. Insufficient Amount Of New Alloy Incorporate at least 30% new alloy with each melt to restore alloy’s physical properties.

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PROBLEM SOLUTION

c. Contaminated Alloy Make certain that burs, stones, points and casting crucibles are not cross contaminated with any other alloy. Do not mix different alloys.

d. Incorrect Oxidation Procedure Verify whether the alloy being used requires a vacuum hold. Follow alloy manufacturer’s oxidation instructions.

e. Rapid Preheating Of Powder Opaque

Increase the preheating time. The opaque should be chalk white prior to entering the furnace.

f. Rapid Preheating Of Paste Opaque Proper drying procedure is critical for paste opaque. Prior to firing paste opaque, do not place framework on oven platform before it reached idle temperature. Follow porcelain firing chart for proper drying times.

g. Contaminated Paste Opaque Make certain no water is mixed in with paste opaque. Paste opaque contains a special liquid. Framework and opaque brushes must be properly dry, free of any moisture.

h. Soldering Flux Make certain no excess flux exists in or on the alloy.

i. Do Not Blow Dry Metal Surface With Compressed Air

Some air compressors contain contaminating oils in their air lines that may come in contact with metal surfaces.

j. Handling Metal Surfaces Oils from fingertips may transfer to metal’s surface causing

contamination.

k. Sandblaster Air Pressure Set Above 60 psi

If using 50 micron aluminous oxide, air pressure above 60 psi may cause aluminous oxide particles to become imbedded into the alloy, causing contamination. For high gold PFM alloys, set pressure to 30 psi.

l. Presence Of Carbon In High Palladium Alloys

High palladium alloys are extremely sensitive to carbon contamination. Do not allow the alloy to come in contact with carbon products, i.e., investment containing carbon, carbon lined casting crucibles, etc.

m. Metal Not Ultrasonically Cleaned Ultrasonically clean (do not steam clean) in distilled water for 10 minutes.

n. Porosity See page 1 #1

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PROBLEM SOLUTION

2. CRACKS IN OPAQUE

a. Thick Opaque Mix Apply opaque in a creamy, thin consistency.

b. Rapid Preheating See page 17 #1-e

c. Uneven Thickness Apply even layer. Two thin opaque applications are preferable to one thick coat.

3. PORCELAIN BUBBLES

a. Inadequate Condensation Body/Dentine

Apply porcelain without entrapping air. Remove excess moisture.

b. Dirt And/Or Dust Ensure that framework and opaque surfaces are clean.

c. Contaminated Liquid Medium Seal all bottles of medium when not in use.

d. Improper Burs And Abrasives Maintain separate non-contaminating abrasives for each alloy. Do not cross contaminate.

e. Improper Metal Preparation When finishing porcelain bearing surfaces, it is recommended you grind in one direction only. Do not use high speed or press to hard while grinding. Soft PFM alloys can easily fold over with too much pressure from burrs and stones, trapping air and causing bubbles in opaque and porcelain.

f. Porosity In Metal Check metal surface for any porosity.See section 1 on opaque bubbling, page 16 #1

4. CHECKS, CRACKS AND CRAZING

a. Difference In Coefficient Of Thermal Expansion Between Porcelain And Alloy

Make sure that alloy and porcelain are compatible with each other. Metal C.T.E. should be slightly higher than porcelain in order to be compatible with each other.

b. Over Fired, Over Glazed Verify furnace calibration and firing cycle. Check oven characteristics by making a porcelain tab (approximately the size of a dime) out of transparent insisal powder. When properly fired, you should be able to read print through it.

c. Incorrect Maturity Of Opaque (Under Or Over Fired)

Observe proper visual indications illustrating proper porcelain maturity.

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PROBLEM SOLUTION

d. Thermal Shock Avoid cold objects, such as instruments, contacting porcelain while cooling.

e. Alloy Overheated Some trace elements get burned out of the overheated alloy, changing alloy’s physical properties. Add 50% new alloy when casting previously casted alloy.

f. Failure To Add Adequate Amount Of New Alloy When Casting

In order to restore the original CTE of the alloy, at least 30% - 50% new alloy must be added to rejuvenate alloy’s original physical properties. If this is not done, alloys CTE will likely be altered.

g. Rapid Preheating Increase preheating time.

h. Improper Metal Design Porcelain bearing surface should not have sharp angles. Adequate support for porcelain must be designed into the metal substructure.

i. Rapid Firing Cycle Verify temperature rate of climb.

j. Porcelain Worked Too Dry Condense porcelain uniformly. Unfired porcelain will crack if handled too dry.

k. Improper Cooling Procedure Observe alloy or porcelain manufacturer’s recommendation for customized cooling.

l. Improper Porcelain Support Porcelain should not exceed a thickness of more than 2 mm per unit.

5. DISCOLORATION

a. Contaminated Muffle Purge the muffle according to the furnace manufacturer’s instructions.

b. Contaminated Alloy Do not cross contaminate crucible and abrasives.

c. Contaminated Acid Change your hydrofluoric acid regularly.

d. Flux Contamination Remove any excess flux from metal surfaces with acid bath after soldering, and before beginning the finishing process.

e. Thin Opaque Application Apply more coats of opaque if necessary.

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PROBLEM SOLUTION

f. Over Fired Porcelain Calibrate furnace and check firing cycle by utilizing a test tab as explained in page 17 # 4-b.

g. Un-Opaqued Alloy Surface Be certain to properly opaque porcelain bearing surfaces. Alloy’s oxide will bleed through un-opaqued areas, and affect the color of the porcelain once fired.

6. MILKY OR CHALKY APPEARANCE

a. Under Fired Opaque Verify proper firing temperature.

b. Improper Temperature Check furnace calibration and utilize a test tab as explained in page 17# 4-b.

c. Insufficient Vacuum Insure proper level of vacuum is achieved and follow porcelain firing cycle when vacuum should star and be released.

d. Wrong Liquid Medium Used Use recommended liquid medium, or distilled water.

e. Rewetting Of Porcelain During Build Up On Substructure

Do not allow porcelain build up to completely dry.

7. INSUFFICIENT GLAZE

a. Glaze Temperature Too Low Raise temperature and/or hold time of glazing firing cycle.

b. False Temperature Reading Calibrate your furnace and utilize a porcelain test tab as explained in page 17 #4-b.

c. Under Fired Porcelain To obtain a natural glaze, porcelain powders must be brought to full firing maturity during the first bake. If this is not done, a semi-glaze will be achieved regardless of how long the firing cycle is. Check with porcelain appearance when full maturity is reached.

8. PORCELAIN BOND FAILURE

a. Difference In Coefficient Of Thermal Expansion Between Porcelain And Alloy

See page 17 #4-a

b. Underfire Opaque See above, #6-a

c. Alloy Contamination See page 15 #1-c

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PROBLEM SOLUTION

d. Alloy Overheated When Cast Overheating the alloy during casting will change alloy’s physical properties.

e. Insufficient Amount Of New Alloy See page 15 #1-b

f. Improper Oxidation (Degassing) Follow alloy manufacturer’s recommendation for proper oxidation (degassing) cycle.

g. Insufficient Drying Of Paste Opaque Improper drying of paste opaque prior to firing will result in an insufficient bond between the ceramics and the alloy surface. Follow porcelain manufactures instructions for recommended drying times, and handling techniques.

h. Contaminated Aluminous Oxide Used For Sandblasting

Change aluminous oxide often or use a non-recycled blasting unit to avoid cross contamination with other alloys.

20 of 20

CELCIUS/FAHRENHEIT CONVERSION CHARTLocate the temperature you wish to convert in the Reference Column (REF)► To find the Fahrenheit equivalent - read to the RIGHT► To find the Celsius equivalent - read to the LEFT

Example: You are working at 532ºC. Find 990 in the reference column. Read to the right. Fahrenheit equivalent is 1814º

°C REF °F °C REF °F °C REF °F °C REF °F °C REF °F °C REF °F-17.8 0 32 24.4 76 168.8 321 610 1130 743 1370 2498 1166 2130 3866 1588 2890 5234-17.2 1 33.8 25.0 77 170.6 327 620 1148 749 1380 2516 1171 2140 3884 1593 2900 5252-16.7 2 35.6 25.6 78 172.4 332 630 1166 754 1390 2534 1177 2150 3902 1599 2910 5270-16.1 3 37.4 26.1 79 174.2 338 640 1184 760 1400 2552 1182 2160 3920 1604 2920 5288-15.6 4 39.2 26.7 80 176.0 343 650 1202 766 1410 2570 1188 2170 3938 1610 2930 5306-15.0 5 41.0 27.2 81 177.8 349 660 1220 771 1420 2588 1193 2180 3956 1616 2940 5324-14.4 6 42.8 27.8 82 179.6 354 670 1238 777 1430 2606 1199 2190 3974 1621 2950 5342-13.9 7 44.6 28.3 83 181.4 360 680 1256 782 1440 2624 1204 2200 3992 1627 2960 5360-13.3 8 46.4 28.9 84 183.2 366 690 1274 788 1450 2642 1210 2210 4010 1632 2970 5378-12.8 9 48.2 29.4 85 185.0 371 700 1292 793 1460 2660 1216 2220 4028 1638 2980 5396-12.2 10 50.0 30.0 86 186.8 377 710 1310 799 1470 2678 1221 2230 4046 1643 2990 5414-11.7 11 51.8 30.6 87 188.6 382 720 1328 804 1480 2696 1227 2240 4064 1649 3000 5432-11.1 12 53.6 31.1 88 190.4 388 730 1346 810 1490 2714 1232 2250 4082-10.6 13 55.4 31.7 89 192.2 393 740 1364 816 1500 2732 1238 2260 4100-10.0 14 57.2 32.2 90 194.0 399 750 1382 821 1510 2750 1243 2270 4118-9.4 15 59.0 32.8 91 195.8 404 760 1400 827 1520 2768 1249 2280 4136-8.9 16 60.8 33.3 92 197.6 410 770 1418 832 1530 2786 1254 2290 4154-8.3 17 62.6 33.9 93 199.4 416 780 1436 838 1540 2804 1260 2300 4172-7.8 18 64.4 34.4 94 201.2 421 790 1454 843 1550 2822 1266 2310 4190-7.2 19 66.2 35.0 95 203.0 427 800 1472 849 1560 2840 1271 2320 4208-6.7 20 68.0 35.6 96 204.8 432 810 1490 854 1570 2858 1277 2330 4226-6.1 21 69.8 36.1 97 206.6 438 820 1508 860 1580 2876 1282 2340 4244-5.6 22 71.6 36.7 98 208.4 443 830 1526 866 1590 2894 1288 2350 4262-5.0 23 73.4 37.2 99 210.2 449 840 1544 871 1600 2912 1293 2360 4280-4.4 24 75.2 37.8 100 212.0 454 850 1562 877 1610 2930 1299 2370 4298-3.9 25 77.0 43.0 110 230.0 460 860 1580 882 1620 2948 1304 2380 4316-3.3 26 78.8 49.0 120 248.0 466 870 1598 888 1630 2966 1310 2390 4334-2.8 27 80.6 54.0 130 266.0 471 880 1616 893 1640 2984 1316 2400 4352-2.2 28 82.4 60.0 140 284.0 477 890 1634 899 1650 3002 1321 2410 4370-1.7 29 84.2 66.0 150 302.0 482 900 1652 904 1660 3020 1327 2420 4388-1.1 30 86.0 71.0 160 320.0 488 910 1670 910 1670 3038 1332 2430 4406-0.6 31 87.8 77.0 170 338.0 493 920 1688 916 1680 3056 1338 2440 44240.0 32 89.6 82.0 180 356.0 499 930 1706 921 1690 3074 1343 2450 44420.6 33 91.4 88.0 190 347.0 504 940 1724 927 1700 3092 1349 2460 44601.1 34 63.2 93.0 200 392.0 510 950 1742 932 1710 3110 1354 2470 44781.7 35 95.0 99.0 210 410.0 516 960 1760 938 1720 3128 1360 2480 44962.2 36 96.8 100.0 212 413.6 521 970 1778 943 1730 3146 1366 2490 45142.8 37 98.6 104.0 220 428.0 527 980 1796 949 1740 3164 1371 2500 45323.3 38 100.4 110.0 230 446.0 532 990 1814 954 1750 3182 1377 2510 45503.9 39 102.2 116.0 240 464.0 538 1000 1832 960 1760 3200 1382 2520 45684.4 40 104.0 121.0 250 482.0 543 1010 1850 966 1770 3218 1388 2530 45865.0 41 105.8 127.0 260 500.0 549 1020 1868 971 1780 3236 1393 2540 46045.6 42 107.6 132.0 270 518.0 554 1030 1886 977 1790 3254 1399 2550 46226.1 43 109.4 138.0 280 536.0 560 1040 1904 982 1800 3272 1404 2560 46406.7 44 111.2 143.0 290 554.0 566 1050 1922 988 1810 3290 1410 2570 46587.2 45 113.0 149.0 300 572.0 571 1060 1940 993 1820 3308 1416 2580 46767.8 46 114.8 154.0 310 590.0 577 1070 1958 999 1830 3326 1421 2590 46948.3 47 116.6 160.0 320 608.0 582 1080 1976 1004 1840 3344 1427 2600 47128.9 48 118.4 166.0 330 626.0 588 1090 1994 1010 1850 3362 1432 2610 47309.4 49 120.2 171.0 340 644.0 593 1100 2012 1016 1860 3380 1438 2620 4748

10.0 50 122.0 177.0 350 662.0 599 1110 2030 1021 1870 3398 1443 2630 476610.6 51 123.8 182.0 360 680.0 604 1120 2048 1027 1880 3416 1449 2640 478411.1 52 125.6 188.0 370 698.0 610 1130 2066 1032 1890 3434 1454 2650 480211.7 53 127.4 193.0 380 716.0 616 1140 2084 1038 1900 3452 1460 2660 482012.2 54 129.2 199.0 390 734.0 621 1150 2102 1043 1910 3470 1466 2670 483812.8 55 131.0 204.0 400 752.0 627 1160 2120 1049 1920 3488 1471 2680 485613.3 56 132.8 210.0 410 770.0 632 1170 2138 1054 1930 3506 1477 2690 487413.9 57 134.6 216.0 420 788.0 638 1180 2156 1060 1940 3524 1482 2700 489214.4 58 136.4 221.0 430 806.0 643 1190 2174 1066 1950 3542 1488 2710 491015.0 59 138.2 227.0 440 824.0 649 1200 2192 1071 1960 3560 1493 2720 492815.6 60 140.0 232.0 450 842.0 654 1210 2210 1077 1970 3578 1499 2730 494616.1 61 141.8 238.0 460 860.0 660 1220 2228 1082 1980 3596 1504 2740 496416.7 62 143.6 243.0 470 878.0 666 1230 2246 1088 1990 3614 1510 2750 498217.2 63 145.4 249.0 480 896.0 671 1240 2264 1093 2000 3632 1516 2760 500017.8 64 147.2 254.0 490 914.0 677 1250 2282 1099 2010 3650 1521 2770 501818.3 65 149.0 260.0 500 932.0 682 1260 2300 1104 2020 3668 1527 2780 503618.9 66 150.8 266.0 510 950.0 688 1270 2318 1110 2030 3686 1532 2790 505419.4 67 152.6 271.0 520 968.0 693 1280 2336 1116 2040 3704 1538 2800 507220.0 68 154.4 277.0 530 986.0 699 1290 2354 1121 2050 3722 1543 2810 509020.6 69 156.2 282.0 540 1004.0 704 1300 2372 1127 2060 3740 1549 2820 510821.1 70 158.0 288.0 550 1022.0 710 1310 2390 1132 2070 3758 1554 2830 512621.7 71 159.8 293.0 560 1040.0 716 1320 2408 1138 2080 3776 1560 2840 514422.2 72 161.6 299.0 570 1058.0 721 1330 2426 1143 2090 3794 1566 2850 516222.8 73 163.4 304.0 580 1076.0 727 1340 2444 1149 2100 3812 1571 2860 518023.3 74 165.2 310.0 590 1094.0 732 1350 2462 1154 2110 3830 1577 2870 519823.9 75 167.0 316.0 600 1112.0 738 1360 2480 1160 2120 3848 1582 2880 5216

TEMPERATURE CONVERSION TABLE

DWT-GRAM-OZ CONVERSION CHART

DWT GRAM OZ

1 1.56 0.052 3.11 0.13 4.67 0.154 6.22 0.25 7.78 0.256 9.33 0.37 10.89 0.358 12.44 0.49 14 0.45

10 15.55 0.511 17.11 0.5512 18.66 0.613 20.22 0.6514 21.77 0.715 23.33 0.7516 24.88 0.817 26.44 0.8518 27.99 0.919 29.55 0.9520 31.1 121 32.66 1.0522 34.21 1.123 35.77 1.1524 37.32 1.225 38.88 1.2526 40.43 1.327 41.99 1.3528 43.54 1.429 45.1 1.4530 46.65 1.5

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