technical reference manual on techniques for reducing or … · 2018-06-13 · i technical...

I

TECHNICAL REFERENCE MANUAL

on

TECHNIQUES FOR REDUCING OR ELIMINATING RELEASES OF TOXIC CHEMICALS IN METAL PAINTING

to the

U.S. Environmental Protection Agency Center for Environmental Research Information

. . . Putting Technology To M r k

TABLE OF CONTENTS

Page

I . INTRODUCTION AND BACKGROUND ............................ 1 . Current Situation and Trends ................................... 2 . Production Limits and Tax Disincentives ........................... 3 . Overview of Toxic Waste and VOC Elimination or

Reduction Techniques .........................................

11 . USE OF ALTERNATE COATING FORMULATIONS ..................

A. High Solids Coatings .......................................... 1 . General Information ...................................... 2 . Equipment Requirements .................................. . 3 . Advantages and Disadvantages of High-Solids Coatings ........... 4 . CaseHistory ............................................

B . Waterborne Coatings .......................................... 1 . General Information ......................................

3 . Advantages and Disadvantages of Waterborne Coatings ........... 2 . Equipment Requirements ..................................

C . Powder Coatings .............................................

1 . General Information ......................................

3 . Cost Comparison With Solvent Paint System ................... 4 . Summary of Advantages and Disadvantages of

Powder Coatings ......................................... 5 Case History

2 . Equipment and Materials ..................................

. ............................................ D . Electrocoatings ............................................... I 1 . General Information ......................................

2 . Technique .............................................. f

3 . Advantages and Disadvantages of Electrocoatings ............... 4 . CaseHistory ............................................

E . Other Coating Systems ......................................... . . 1 . Two-Component Reactive Liquid Coatings .....................

3 . Radiation Curable Coatings ................................ 2 . Supercritical CO, Coatings .................................

I- 1

1-3 1-4

1-5

11-1

11-3

11-3 11-3 11-4 11-5

11-9

11-9 11-9

11-10

11-11

11-11 11-13 11-13

11-16 11-18

11-20

11-20 11-20 11-21 11-22

11-23

11-23 11-23 11-24

Metal Painling i Table of Contents

TABLE OF CONTENTS (Continued)

F . Checklist for Using Alternate Coating Formulations .................. it-27 G . References .................................................. ii-28

111 . MORE EFFICIENT APPLICATION ................................. 111-1

A. Airless and Air.Assisted. Airless Spray ............................ 111-5

1 . Airless Spray Technique ................................... 111-5 2 . Air.Assisted. Airless Spray Technique ......................... 111-5

B . Electrostatic Spray and Air-Assisted Electrostatic Spray ............................................ 111-6

. Electrostatic Discs and Bells .................................... 111-8

1 . Use of Electrostatic Devices ................................ h1-8 2 . Advantages and Disadvantages of Electrostatic Coating ........... 111-10

D . High.Vo1ume. Low-Pressure (HVLP) Spray ........................ III-11

1 . Equipment Requirements .................................. 111-11 2 . Advantages and Disadvantages of H W ...................... 111-12

E . Checklist for More Efficient Application ........................... III-14 F . References .................................................. 111-15

IV . MINIMIZJNG WASTE THROUGH IMPROVED OPERATIONS .......... 1v-1

A. Direct Transfer of Paint to the Guns .............................. 1v-1 B . Heated Spray ................................................. 1v-3

1 . Effective Applications ..................................... 1v-3 . 2 . Aerosols Maintenance and Touchup .......................... 1v-4

I 3 . Advantages and Disadvantages of Heated Spray Systems ........................................... 1v-4

C . Reuse or Recycling of Waste Solvents ............................. 1v-6

1 . Techniques for Reusing Waste Solvents ....................... N - 6 2 . Techniques for Recycling Waste Solvents ...................... 1v-6

.D . Other Operating Practices for Waste Minimization ................... 1v-8

1 . Inventory Control ........................................ 1v-8 2 . Standardization of Paints ................................... 1v-8

Metal Painting ii Table of contenrs

TABLE OF CONTENTS (Continued)

3 . Improved Scheduling ...................................... N-9 4 . Proper Training of Personnel ............................... N-9

E . Checklist for Improved Operations ............................... 1v-10 F . References .................................................. N-11

V . SUPPLIERS ..................................................... V-1 VI . BIBLIOGRAPHY ................................................ v1-1 VIE . SUPPLEMENTAL AND BACKUP MATERIALS ....................... v1e-1 VIII . COURSEPACK ................................................. Vm-1

1’

Metal Painting iii Table of colntents

SECTION I INTRODUCTION AND BACKGROUND

Waste minimization makes environmental, hearth, and economic sense.

This workshop describes techniques to minimize toxi.c/vOC releases.

Conventional paints have three basic components:

A film-forming binder consisting of resins or drying oils

A volatile organic solvent and/or water to maintain fluidity

A pigment system containing coloring, opacifiers, and various extenders.

Typical solvent-based paints contain 60 percent to 80 percent VOCs, some of which may be toxic. As the paint dries, the solvent evaporates creating a potential air pollution and health problem.

Aside from the important environmental and health reasons for reducing or eliminating toxic chemicals and volatile organic compounds (VOCs), there can be real economic benefits in adopting environmentally acceptable materials and more efficient methods into your painting operation. Many times the economic investment is small, but the return is significant. In some cases employee training and only minor equipment modification is needed. In metal painting several avenues of toxic waste and VOC reduction are available. These include:

Conversion to paints or coatings that contain little or no toxic chemicals and/or VOCs

Using paint o r coating application techniques that are more efficient and therefore generate less toxic waste and/or VOCs

Improving other internal operations to minimize the use and waste of toxics and/or VOCs.

These actions can save on production costs and eliminate or lower your hazardous waste disposal costs. If the “Cradle to Grave” liability under RCRA can be reduced or eliminated by minimizing hazardous wastes, then savings in liability o r insurance costs are also a possibility.

The goal of this workshop is to show where your metal painting operations may be improved for greater profitability and a cleaner environment. The discussions are divided into four parts:

I. Introduction and Background II. Use of Alternate Coating Formulations

2

Metal Painting 1-1 Introduction and Background

El. IV.

More Efficient Application of Paint General Improvement of Painting Operations.

Metal Painting 1-2 Introduction and Background

1. Current Situation and Trends

Some of the 17 targeted chemicals are used in paint systems.

Pigments based on lead, mercury, and cadmium are being phased out.

Under the Superfund Amendments and Reauthorization Act of 1986 (SARA), 17 toxic chemicals are targeted for reduced use because of their serious known health and environmental effects. These chemicals were also chosen because of the high number of release sources and/or high volumes of release. The 17 targeted chemicals are:

Benzene Cadmium Carbon Tetrachloride Chloroform Chromium Cyanide Lead Mercury Methyl ethyl ketone

Methyl isobutyl ketone Nickel Tetrachloroethylene Toluene 1, 1, 1-Trichloroet hane Xylenes Methylene chloride Trichloroethylene

Lead, mercury, and cadmium are present in some paint pigments. These constituents are toxic. Use of these metals has been or shortly will be eliminated from paints and less toxic additives will fulfill their func- tion. Close attention should be given to the constituents contained in the paints and coatings that you may use. Paints containing lead, mercury, and cadmium should be avoided if possible.

in this manual will in most cases minimize use and release of these metals. However, this manual focuses primarily on minimizing the toxic solvents and VOCs that are likely to be found in paints, paint thinners, and solvents that are used in paint operations and cleanup. Of the 17 targeted toxic chemicals listed above, the following are used as solvents that are likely to be encountered in painting operations:

Alternate coatings and waste minimization techniques addressed

Methyl ethyl ketone Methyl isobutyl ketone Methylene chloride Toluene l,l,l-Trichloroethane Xylenes Trichlorethylene.

One might expect further future regulation of these solvents.

Metal Painting 1-3 Innoduction and Backpund

I

2. Production Limits and Tax Disincentives

Under the Montreal protocol, two widely used, ozone depleting chemicals (chlorofluorocarbons and l,l,l-trichloroethane) have been scheduled for elimination from use. A recent presidential directive calls for eliminating production of these chemicals by December 31, 1995. In

TCA will be highly taxed and Its duction DhaSed out

addition, taxes that are being imposed will make their use significantly more expensive. Most important to paint users is the phase out of l , l , l -

by year-end 1995. trichloroethane (TCA). The tax schedule for TCA is as follows:

Current 13.7 centsfpound 1993 16.7 centdpound 1994 30.0 cents/pound 1995 31.0 centsfpound

Recycled TCA is not subject to tax. In summary, production of virgin chlorinated solvents will be curtailed between now and year-end 1995, therefore becoming less available and significantly more expensive. Competition for recycled materials will increase.

TCA is notable because it is not a VOC. However, its use as a substitute for VOCs, such as trichloroethylene, is being cut short not only because of its ozone depletion characteristics but because of its toxicity. Future use and disposal of ozone depletors and toxic chemicals and emissions from VOCs are and will continue to be more closely controlled. Consequently, reducing the use of toxic chemicals (and VOC emitters) will not only yield definite benefits now, but increased benefits in the future.

Metal Painting 1-4 Inmduction and Background

I

The use of low- solvent paints, high-efficiency

and good house-

cantly reduce toxic chemicaVVOC lX?lt2€tSeS.

spray techniques,

keeping will Signifi-

1

3. Overview of Toxic Waste and VOC Elimination or Reduction Techniques

Several alternatives to current solvent-based paints are available

0 High solids coatings Waterborne coatings Powder coatings

0 Other coating systems.

now to reduce toxics and/or VOCs. These include substitution with:

The use of high-efficiency spray techniques is another approach to minimizing toxic wastes and VOCs. In this case less paint (and solvent) is used and less is wasted. These techniques offer improvements over commonly used air spray and include:

Airless spray and air-assisted airless spray 0 Electrostatic spray (air spray, and air-assisted airless spray) 0 Electrostatic bells and high-speed discs

High-volume, low-pressure (HVLP) spray 0 Electrocoating

Flow coating. A number of operation improvements can be instituted to mini-

mize the creation of toxic waste and VOCs. These include:

0 Direct transfer of paint to guns

Use of heated paint and transfer lines (with high solids coatings and lower solvent content)

Reuse and recycling of waste solvents

Other good housekeeping practices

Substrate surface preparation.

Metal Painting 1-5 Introduction and BaclCqround

A. HIGH SOLIDS COATINGS

HQh Solids C o a t - ings are easily adapted and practical substitutes for common solvent- based paints.

Use of high solids

VOC emissions and may reduce toxic chemical emissions and wastes.

coatings will reduce

High Solids coatings may be applied by a variety of methods. Paint heaters are needed to reduce the viscosity of many hlgh solids COatingS.

/

High solids coatings can be substituted for the normally used solvent-based paints with little effort and expense. Techniques are described in various recent publications, including the Hazardous Waste Minimization Handbook (1989), Finishing Handbook and Directory (1991), Metal Finishing Guidebook and Directory (1991), and the New York State Waste Reduction Guidance Manual (ICF 1989).

1. General Information

High solids coatings contain less solvent than standard solvent- based paints. They can be used as substitutes for normally used solvent- based paints with little quality penalty or increased expense. The finished coat obtained from high solids coatings is comparable to typical solvent- based coatings. The primary advantage of high solids coatings is significantly reduced VOC emissions. U p to 50 percent reduction is possible, depending on the paint system you are currently using. High solids coatings may also decrease toxic chemical emissions; however, you should check the chemical content of the paint you are currently using against the contents of the high solids coating that you plan to use, to be sure that there is a significant toxic chemical difference.

2. Equipment Requirements

The equipment commonly used for applying solvent-based paints

0 air-atomized sprayers airless sprayers airless electrostatic sprayers electrostatic bells and discs high-volume, low-pressure (HVLP) sprayers.

can be used to apply high solids coatings. This equipment includes:

Although high solids coatings are very similar to the solvent-based paints you may be using, there are some differences. Usually they contain polyester or acrylic resin varieties with special low molecular weight oligomers instead of polymers and copolymers. This results in lower viscosity. However, even with these special additives high solids coatings may require the use of heated spraying systems. The use of paint heaters is the only significant processing change likely to be required in the

Metal Painting II-3 Altemate Formulations

Oven drying might be required.

Principal advantages of high solids coatings are evident in lower cost and lower energy consumption.

Disadvantages of high solids coatings include high viscosity and sticlq surface until cured.

changeover to high solids coating. Some high solids coatings that are available contain enough solvent to be used without heating.

High solids coatings usually require oven drying. Some composi- tions that contain slightly higher solvent contents are air dryable; however, the trade-off is between the use of drying ovens versus greater solvent content.

3. Advantages and Disadvantages of High-Solids Coatings

Aside from protecting the environmental, substituting high solids coatings for the common solvent-based coatings yields the following advantages:

Cost savings through reduction in wasted solvent

Fewer gallons of coating are needed, saving on storage space, materials handling, and possibly shipping costs

Energy savings in baking oven make-up air.

Some disadvantages of using high solids coatings include the following:

High solids coatings show a high viscosity change with temperature, requiring that a reasonably uniform temperature be maintained. Fail-safe paint heaters should be used.

High solids films stay sticky until heated in the oven. Pickup of airborne particles cause a rough finish. Good air quality maintenance and control of air movement in the spray booth and the flash-off zone are important.

At one time it appeared that high solids coatings would become the “standard” replacement for solvent-based coatings. However, devel- opments in water-based coatings and solvent free powder coating have led to highly acceptable systems that are even more environmentally acceptable than high solids coatings. Even so, high solids coatings have established a significant market niche (see Figure II-2).

I ’ ./ Metal Painting 11-4 Altemute Fomuclanbns

4. Case History

Operation: Great Dane Trailers

Technique: Switch From Paint Thinning to Paint Heaters and Reuse of Paint Waste Still Bottoms in an Undercoat Primer

Background

Great Dane Trailers Tennessee, Inc. is a Memphis manufacturer of platform truck trailers. Their efforts at waste minimization won them the 1991 Governor’s Award for Excellence for Hazardous Waste Management.

Description of the Manufacturing Process

The plant manufactures over-the-road platform trailers, curtain- side trailers, and converter dollies. The trailers are assembled from steel parts fabricated in the plant. The parts are a wide assortment of steel structural shapes, formed shapes, sheet, plate, pipe, tubing, etc. The parts are assembled primarily by the welding process; some fasteners are used. There are also many purchased items which include such things as air brake accumulators and shoes, drums, clearance lamps, tires, suspension posts and springs, heavy cast iron wheel hubs, pre-painted wheels, and wood and aluminum flooring.

When the trailer reached the end of the assembly line, it was prepared for painting. Items such as wheels, tires, and air and electrical connectors were covered with plastic or masked off. The trailer was then moved into a large paint booth where it was washed down with TCA prior to painting. The washdown cleans and degreases the steel surfaces of the trailer.

of coatings using various colors. The different types of coatings usually applied are a primer, enamel or polyurethane topcoat, color matching, rust-preventive visible undercoating, and a black (not normally visible) undercoat. Following painting, the trailer is allowed to dry in ambient air. After finishing procedures are completed @e., installation of serial plates, nameplates, mud flaps, and lights), the trailer is moved to the storage yard for pickup or delivery to the customer.

Actual trailer painting may involve as many as four different types

~~~

Metal Painting 11-5 Altemate Fomuclatiom

I

Over the 1987-1990 period, the following annual average emissions and RCRA waste were generated:

Emissions Emissions Hazardous from from Paint

Painting Degreasing Waste

Average annual amount, pounds 45,100 179,900 12332

The emissions resulted from the use of TCA, both as a paint thinner and as a cleaning degreasing agent (Note: in 1988 TCA was substituted for v l ene and other paint solvents due to an EPA requirement). Sources of the waste were as follows:

0 Solvent emissions - paint thinning operation - degreasing operation

RCRAwaste - leftover paints - solvent/paint waste from cleaning of paint lines.

Waste Reduction Measures

A program was started in February 1990 to evaluate process changes, alternative coatings, and other means to both reduce vapor emissions and hazardous waste. As part of the program, the University of Tennessee Center for Industrial Services was asked to conduct a waste reduction study. Equipment and coating vendors also assisted in the program, which considered only current technology. After extensive tests, the following changes were made:

(1) The paint system was modified by adding high temperature heaters to raise liquid temperatures to 160 F. This change lowered the viscosity of the high solids paint and eliminated the need for thinning with TCA. Recirculating paint lines were also installed to allow paint to recirculate through the heaters when spraying was not in progress. These changes resulted in significant reductions in the amount of TCA previously used as a thinner. Total capital costs were $20,815 for the purchase of an explosion proof mixing room heater, two in-line heaters, a paint recirculating system, and paint manifold system.

(2) Cleaning and degreasing of the trailers was moved from the paint booth to other stations on the production line. This

Metal Painting 11-6 Altemate Formulatiom

change allowed the water soluble degreaser time to dry prior to painting. No capital outlay was needed to effect this change.

(3) The recycling of paint wastes was implemented after experi- mentation had shown that a vacuum distillation unit could be used to recycle solvent for reuse in cleaning paint lines. More significantly, experiments conducted by Lilly Industrial Coatings showed the paint sludge still bottoms could also be utilized. The still bottoms are blended with oils, hardeners, and black pigment to produce a superior undercoat for use on the undersurfaces of the trailers. The cost of the new, recycled primer is about the same as previously purchased undercoat - about $3 per gallon. The capital cost for this recycling innovation was $23,572. This includes a 60-gallon distillation unit, a vacuum unit, and a 5-HP blender. Virtu- ally 100 percent of the paint-related material previously shipped off site as a hazardous waste is now recycled.

As a result of these changes, annual hazardous waste output was reduced by 98 percent and TCA emissions were reduced by 90 percent.

Economics

The total capital outlay for the changes made was $44,387. Reported savings were as follows:

Annual Savings

$73,440 Elimination of TCA purchases for degreasing @ $0.4inb

- less purchase of water-based cleaners (not reported)

Elimination of hazardous paint waste disposal $30,000

Elimination of TCA purchases for paint line $2O,oOo

Elimination of undercoat purchases $12,000

- less purchase of oil, hardeners, and pig- ($12,000)

cost

cleaning

ments for blending with still bottoms to make undercoat

Estimated Total Savings $123,440

No changes in other operating costs such as energy costs and no project costs were noted by Great Dane. Based on the above available net savings, a simple payback period of 0.36 years is calculated. That is, the

Metal Painting KI-7 Altemute FormuIptions

investment of $44,387 is recovered in less than 5 months by the savings afforded by the project, indicating an extremely high rate of return.

, t

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Metal Painting II-8 A l t m t e Fontuclations

B. WATERBORNE COATINGS

Waterborne coating systems also are easily adapted and

tutes for solvent-

systems.

practical Substi-

based paint

Use of waterborne paints will eliminate or reduce VOC emissions and toxic Qaste.

Waterborne coatings provide only moderate protection to metal surfaces.

Waterborne coating systems are easy to adapt and may serve as practical substitutes for solvent-based paint systems. Techniques are described in various recent publications, including the Hazardous Waste Minimization Handbook (1989), Finishing Handbook and Directory (1991), Metal Finishing Guidebook and Directory (1991), and the New York State Waste Reduction Guidance Manual (ICF 1989).


Waterborne coatings may contain up to 80 percent water as a carrier fluid that replaces nearly all the organic solvent. Typical waterborne coatings contain 5 to 20 percent of an organic solvent. The organic solvent, used to aid wetting, control viscosity, and disperse pigments, is usually a non-VOC such as glycol ether or diacetone alcohol. Waterborne coatings are supplied in air-drying and oven-drying versions. Acrylic, polyester, epoxide, epoxide ester, alkyd, and phenolic resins are used in waterborne systems.


For most paint applications, you can apply waterborne coatings with the same equipment used for applying solvent-based coatings. Con- ventional air spray is widely used, as is airless spray. Electrostatic spray can be used if the electrically conductive waterborne paint is isolated from the electrostatic system. Usually the investment required to switch to waterborne coatings is very small. If your requirements call for an oven drying version of waterborne coatings, an investment in a drying oven will be needed, provided you do not already have drying capabilities.

ate protection. They are widely used for protection and decoration of metals. Nonmetallics are also protected using waterborne coatings. One of the largest applications for metal protection using waterborne coatings is in the automotive field. The principal use is for primer coat application, which is performed using electrodeposition. Another large use is in the application of one-coat finishes for aluminum window and door frames.

Waterborne coatings are used where surfaces require only moder-

Metal Painting II-9 Alternate Formulations

3. Advantages and Disadvantages of Waterborne Coatings

Advantages of waterborne coatings include little waste

cleanup, improved worker safety, and long storage life.

disposal, easy

Disadvahtages of waterborne coatings include greater needs for surface cleaning and preparation, elimination of dirt from the work area, and temperature and humidity control.

The advantages of using waterborne coatings compared to solvent-based coatings include:

Minimization o r elimination of hazardous waste disposal

Easy cleanup of overspray (prior to curing)

Reduced toxicity and odor, resulting in improved worker safety and comfort

Good storage life.

Major disadvantages of using waterborne coatings versus solvent-based coatings include:

Requirement for a surface that is completely free of oil-type films to ensure that the paint will adhere well

Longer drying times or oven drying on cold and h’umid days

Prompt cleanup of spills and oversprays before curing

Greater susceptibility to dirt pickup due to the increased drying time; need for careful filtration of incoming booth air and correction of possible dirt pickup situations, such as from overhead conveyors

Need for better temperature and humidity control. If temperature is raised too fast, the evaporating water will cause pitting of the coating. If the humidity is too high o r the temperature too low, the coating on vertical surfaces will sag. If the humidity is too low and the temperature too high, the coating will not flow, causing surface roughness known as the orange peel effect.

Metal Painting II- 10 Alternate Fomuclatiom

C. POWDER COATINGS

Powder coatings eliminate essentially all VOCs and toxic chemicals, and provide highquality coatings.

Powder coatings offer several performance advantages, but coatings are relatively thick.

Powder coating systems eliminate essentially all VOC and toxic chemicals. The coatings are high in quality, but are relatively thick. Tech- niques are described in various recent publications, including the Hazardous Waste Minimization Handbook (1989), Finishing Handbook and Directory (1991), Metal Finishing Guidebook and Directory (1991) and the New York State Waste Reduction Guidance Manual (ICF 1989).


Dry powder coating systems emit negligible quantities or no VOCs and toxics, greatly reduce cleanup solvent requirements, and eliminate the need for paint thinners. In addition, there is no wasted paint requiring disposal. Thus, powder coating is extremely friendly to the environment and is worthy of very serious consideration for in-plant coating operations.

finishes. Proponents claim that powder coatings provide superior finishes and exceptionally tough coatings that do not sag, run, or drip during applications.

resins with a built-in curing agent. Table II-1 summarizes the properties of some generic powder coatings currently available.

finishes available in powder coatings include textured, low gloss, high gloss, wrinkle, smooth, clear, pigmented, and metallic. Coating thickness down to about 1.5 mils can be obtained with powder coatings.

A family of thermoplastic resins also is used in powder coatings, including nylon, polyvinyl chloride, fluoropolymers, and polyolefins. Thermoplastic coatings exhibit excellent chemical resistance, toughness, and flexibility. Because of their high melt Viscosity, however, the thermoplastic powders are used primarily in applications where thick films (10 to 60 mils) are required. Fluidized bed technology facilitates the use of thermoplastic powder coatings.

There are also good technical reasons for using powder coating

The principal ingredients of powder coatings are thermosetting

There are also special powder coatings. For instance, decorative

Metal Painling II-11 Altemate Fomudations

Table 11-L Typical properties of thermosetting powder coatings.

b p e r t r

Application thickness, mils

cure cycle: temperature - time (metal temperature)

Epoxypolyes ter TGIC Polyester Acrylic Epoxy Hybrid Polyester Urethane Urethane

1 - 201 1 - 10 1 - 10 1 - 3.5 1 - 3.5

450 F - 3 min 250 F - 30 min

450 F - 3 min 325 F - 25 min

400 F - 7 min 310 F - 20 min

400 F - 7 min 350 F - 17 min

400 F - 7 min 360 F - 25 min

Outdoor weatherability

Pencil hardness

Direct impact resistance? in./lb

Adhesion

Chemical resistance

Source: Technical Brief No. 1, The Powder Coating Institute. 1

~

poor poor excellent very good very good

HB-5H HB-2H HB-2H HB3H HB3H

80 - 160 80 - 160 80 - 160 80 - 160 20 - 60

excellent excellent excellent excellent excellent

excellent very good good good very good

2. Equipment and Materials

Powder coatings are Dry powder painting is performed using an electrostatic gun or, in the case of thick film or low volume needs, by using fluidized bed applied electro-

statically or with a nuidized bed. application.

Electrostatic Application. In electrostatic application a dry powder is metered pneumatically into a compressed-air-driven spray gun. At the gun, a low amperage, high-voltage charge is imparted to the particles. The workpiece is electrically grounded. When the particles are released, they are electrically attracted to the workpiece, and coating takes place. A schematic representation of an electrostatic powder spray setup is shown in Figure 11-3. The workpiece is then conveyed to an oven where it is held until the particles are melted and fused into a smooth coating.

In commercial operations the powder overspray is collected in an air filtration system (see Figure 11-4) and returned to the source for reuse in the coating operation.

Fluidized Bed Application of Powder. A fluidized bed or a “cloud” of particles is maintained by airflow through the bottom of an open-top container. The coating takes place when a heated workpiece is lowered into the fluidized bed. The powder fuses to the workpiece. Upon withdrawal the coated workpiece is then cured in an oven. In some cases fluidized bed applications are performed electrostatically, with a charge being applied to the powder and a grounded workpiece.

Powder Slurry. Some standard electrostatic equipment for liquid coatings may be used to apply powder slurries. Use of powder slurries will allow reduction in powder coating thickness and therefore material cost.

Several other ways may be used to achieve coating with powder; however, electrostatic spray coating is by far the most widely used, followed by fluidized bed coating.

3. Cost Comparison With Solvent Paint System

The operating and maintenance costs for electrostatic powder coating are generally lower than for a solvent painting system performing the same job. In Table 11-2 a cost comparison is made between a

I

2

Metal Painting II-13 Akmate Fomudations

Figure II-3. Schematic of electrostatic spray gun system for powder coating. (EPA 1992)

Metal Painling II-14 Altemute Fomuclatiom

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Figure II-4. Powder coating recovery system. (EPA W )

Metal Painting II-15 Altemate Fomuclations

Conventional Item Solvent

Table II-2. Comparison of annual operating and maintenance costs: conventional solvent painting versus dry powder coating.

Dry Powder

Material

Labor and Cleanup

Maintenance

Energy

$445,200 $370,800

160,200 98,600

2 9 w 17,000

21,400 11,525

Sludge Disposal

Amortization (10-year, straight line)

11 Total Annual I $727,300 I $513,400 11

50,100 975

21,100 14,500

Applied Cost (%/sq ft)

conventional solvent coating operation and a powder system. The comparison is based on achieving a 15-mil coating of polyester versus a l-mil coating of alkyd baking enamel, both at a rate of 1 million square feet per month, for a twocolor operation. In both cases equipment costs were amortized over a 10-year period and included in the operating costs.

Operation and The use of powder, in this case, resulted in substantial operational

0.0606 0.0428

maintenance of powder coating systems are rela-

savings. Total annual operating cost of 4.3 cents per square foot of coating applied were estimated for the powder coating system versus 6.1

tively low. cents for the solvent-based system. The cost of powder coating is most advantageous when little or no color change is required and when VOC control costs and sludge disposal costs of solvent systems are relatively high.

4. Summary of Advantages and Disadvantages of Powder Coatings

The advantages of powder coating are as follows:

a Coating utilization efficiencies can reach 95 to 99 percent with a properly designed recovery system


Advantages of powder coatings include no pollution or waste, high coating etliciencies, and highquality, thick coatings.

Coating operations have essentially no air pollution problems

No hazardous overspray, waste sludge, or contaminated water, is generated for disposal

No solvents are required for adjusting Viscosity or for cleanup

Heavy, uniform coatings can be applied to complex surfaces

“Bridging” is easily achieved, providing smooth finishes over rough surfaces

Thick films (3 to 50 mils) are attainable in fluidized bed application of thermoplastic powders

Coating of edges and corners is continuous and uniform.

The disadvantages of powder coating are as follows:

Disadvantages of powder coatings include dimculty in obtaining thin coatings, matching

hea t-sensitive materials, and recycling overspray.

colors, coating

e

e

e

e

e

e

e , ’

Thin coatings (1 to 2 mils) are difficult to obtain and costly and not always achievable

Thermoset powder overspray is difficult to recycle

If relatively high curing temperatures (7400 F) are required, then soft solder joints, heat treatable aluminum alloys, and other temperature-sensitive materials can be degraded

Color matching and uniformity of color are difficult to achieve

Complete cleanup of system is needed between color changes unless there are separate systems for each color

Workpieces with sharp reentrant angles are difficult to coat uniformly

The Faraday effect (outside corner buildup and inside comer deficiency) results in non-uniform coating.

1

c a p i d investment In a coating system is required.

To introduce powder coating to an existing paint line, a capital investment in special equipment must be made. For entirely new lines, however, investment in powder application equipment is comparable to that for liquid coatings.

Metal Painting II-17 A l t m t e FomuJations

I

5. Case History

Operation: Meco Corporation

/

Technique: Switch from High Solids Coating to Powder Coating

Background

Meco Corporation of Greenville, Tennessee makes barbecue grills and steel tubular folding furniture. As part of their plan to move into another building, they evaluated their painting system (Industrial Exten- sion Service, School of Engineering, North Carolina State University, 1984). At the old plant, they used a high solids system for coating their products. The solvents in the paint, however, required them to comply with VOC emission standards and install an expensive exhaust and ventilation system in the old plant. A large amount of spent solvents, generated by the high solids system during equipment cleanup, was sent to an outside facility for recycling. Spray booth sludges added to the plant’s hazardous waste.

Analysis

Before moving, the company studied alternative coating methods. After investigation and testing, Meco decided to install four electrostatic powder coating lines. The powder system was more expensive to install than a comparable high solids system. However, powder was chosen because it had lower operating costs and because it completely eliminated VOC emissions.

Results

The electrostatic powder coating system utilizes over 90 percent of the coating powder sprayed because the overspray is reclaimed by cyclones and fed back into the hopper. The company reports the following advantages of the powder system over the high solids system:

No VOC emissions, with avoidance of capital and operating costs of a large ventilation system.

Metal Painting II-18 Alternate Fomuclations

No spent solvents or sludges; spray booth cleanup using vacuum cleaners and wet sponges. This eliminates hazardous waste disposal costs.

0 A 10 percent savings in direct labor due to the elimination of paint mixing, reduced cleanup, and other efficiencies.

A higher quality finish, resulting in lower rejection rates. Meco had 35 percent fewer rejects than with the high solids system.

Elimination of pretreatment of the workpiece with zinc phosphate before coating. This resulted in elimination of the generation of a hazardous sludge that had to be sent to a secure landfill. (The powder system allows iron phosphate to be used in pretreatment, eliminating another hazardous waste.)

Metal Painting n-19 Altemate Fomuclationr

D. ELECTROCOATINGS

Electrocaating or Waterborne electrocoating systems may be used to apply uniform, pinhole-free coatings. These systems have low or no VOC emissions and produce lttle toxic waste. Techniques are described in various recent

electrodeposition systems produce little or no toxic

and eliminate VOC emissions.

publications, including the Hazardous Waste Minimization Handbook (1989), Finishing Handbook and Directory (1991), Metal Finishing Guidebook and Directory (1991), the New York State Waste Reduction Guidance Manual (ICF 1989), and the draft U.S. EPA Guide to Appli- cation of Clean Technologies for Replacement Coating Materials (1992).


Waterborne organic In electrocoating or electrodeposition, an organic coating is deposited on a conductive workpiece. The process is similar to electro- plating. The coating material contains waterborne, film forming, organic

electrocoatings contain less than 5 percent organic solvents and have very low viscosity.

macro-ions that are attracted by an electrode of opposite polarity. Epoxy and acrylic coatings are used in currently available systems. Typical solids contents are about 10 percent in electrocoating. Usually about 5 percent organic solvents are present. The coating material has a very low viscosity, nearly that of water.

2. Technique

During electrocoating, the resin and pigment, which are dissolved or suspended in water, are charged, causing them to migrate toward an oppositely charged workpiece. The coating coagulates on the surface of the workpiece. A uniform, pinhole-free coating is achieved because the coated surfaces have reduced conductivity and are shielded from further buildup, with a tendency for the coating material to migrate to bare metal. The accumulation of resin and pigment at the electrode “squeezes out” the uncharged water, forming an adherent film. After coating, the workpiece is withdrawn, rinsed with a water spray and cured in an oven. Most currently used coatings require 5 to 25 minutes a 250 F to 400 F for proper curing. Some electrocoatings can be air cured.

t

Electrocoatings are Oven cured*

Metal Painting n-20 Altemute FomUJari0n.s

I

Electrocoatlng is Typical uses include: priming of auto parts and entire auto bodies, radiator coating, wheels, shelving, various sheet metal structures such as cabinets, subassemblies for tractors and off-road equipment and

most suitable for high-volume applications where no color changes are needed.

many other applications. Many of the electrocoated items are single coat. Color changes are difficult to perform because tank and equipment cleanup is time-consuming. Therefore, electrocoating is most suitable for high-volume applications where few or no color changes are required.

3. Advantages and Disadvantages of Electrocoatings

Advantages of electrocoatings include:

Advantages of electrocoating include greater than 90 percent utilization of coating materials, ability to get very thin coatings in difficult to reach areas, and ability to apply top coats even on uncured electmmats.

Disadvantages of electrocoating include the need for special equipment and relatively high capital outlay.

Use of only small amounts of VOCs and, if VOC control is needed, less elaborate, less expensive controls

Over 90 percent utilization of the coating (dragout at the coating stage and the rinse stage(s) can be filtered out and recycled to the coating tank)

Very thin, very uniform, corrosion resistant coatings

Ability to fully automate coating procedures

Coating of highly recessed areas, such as cavities, creases, and the inside of box areas

Immediately adherent coatings that can be rinsed upon withdrawal from the coating bath

Ability to apply a second coat of water-based or solvent-based paint on uncured electrocoat.

Disadvantages of electrocoating include:

Need for special equipment, including new coating tanks, an extra clean application and curing area, and possibly infrared curing.

Relatively high equipment and operating costs, except with very large numbers of similar parts being coated

High level of training needs for employees not familiar with the process

Need for separate lines for each color.

Metal Painting II-21 Alternate F d a t i o n s

4. Case History

Operation: Emerson Electric

Technique: Choice of Electrocoating Over Electrostatic Solvent-Based Spray Painting

Background

In 1977 the Emerson Electric plant in Murphy, North Carolina, was faced with a decision on the type of paint line it would install for producing a quality finish on diecast aluminum, bench power tool parts. Emerson compared an electrostatic spray process for coating solvent- based paint to the electrocoating process for applying a water-based paint (Industrial Extension Service, School of Engineering, North Carolina State University, 1984).

ing advantages over an electrostatic spray painting system: Emerson found that the electrocoating system offered the follow-

Lower VOC emissions, 70 lbs/day versus 3,040 lbs/day Lower hazardous waste paint, 0 ibs/day versus 160 lbs/day Production cost savings of $1,080,000/year Raw material cost saving of $600,000/year.

The only drawback to the electrocoating system is that it is limited to one color at a time. Each color requires its own tank. The electrocoating system was installed because of the advantages cited.


E. OTHER COATING SYSTEMS

Other low-solvent or solventless coating systems am being developed, including twocomponent, supercritical, CO, and radiation curable systems.

lko-compnen t systems begin curing when mixed. Short pot life can be overcome by using a twin-headed sprayer.

Use of CO, to replace much of the VOC-containing solvent is relatively new and requires special systems.

Other low-solvent or solventless coatings are being developed today. However, most applications are relatively new or represent special uses. They are described in various recent publications, including Indus- trial Extension Service, School of Engineering, North Carolina State University (1984), the draft USEPA Guide to Application of Clean Technologies for Replacement Coating Materials (1992), and “Applica- tion of Paints and Coatings” (Levinson 1988). Brief descriptions of these systems are given here.

1. Two-Component Reactive Liquid Coatings

Twocomponent coating systems are cured by chemical reaction. They are supplied as two components that are mixed just prior to use. Typical of these are two component epoxies, polyesters, and polyure- thanes. One liquid contains reactive resins, and the other contains an activator or catalyst that promotes polymerization of the resins. Once the two components are brought together, curing starts; therefore, they have very short pot lives after mixing. Pot life may vary from a few minutes to 8 hours, then the twocomponent system will start to thicken or gel.

that is fed from two different pots. This spray head can proportion the flow of each component to achieve the desired ratio of liquids. Thus the two components mix on the way to the workpiece and on the workpiece itself. The twocomponent coatings require no solvent and are environmentally benign. However, cleanup usually requires the use of a solvent.

Short pot life can be overcome by using a twin-headed sprayer

2. Supercritical CO, Coatings

The use of carbon dioxide gas as a solvent has been developed by the Union Carbide Corporation. The development is called the UNICAREP system. The carbon dioxide replaces up to 80 percent of the organic solvent normally used for spray applications and little change in existing resin formulations is needed to utilize the process. The advantages and disadvantages are described briefly below.

Metal Painting 11-23 Altemute Fomudationr

Advantages

Except for system cleanup, radiation-

generate essentially no VOCs.

cured coatings

,

W coatings are very thin; generally they are limited to flat surfaces.

Solvent levels are reduced, resulting in reduced VOCs and reduced airflow in curing ovens.

Carbon dioxide use is compatible with conventional and electrostatic spraying equipment.

0 Coatings applied with carbon dioxide gas as a solvent provide a high-quality finish.

Disadvantages

Existing operations will need new carbon dioxide handling equipment .

0 Relatively high investment ($50,000-$100,000) is required.

Solvent use is not completely eliminated from spray application.

System cleanup may require solvents.

3. Radiation Curable Coatings

Coatings that are cured through use of ultraviolet or electron beam exposure are referred to as radiation curable coatings. Generally these coatings contain very little o r no organic solvent and will not dry upon exposure to the air. Instead they cure on exposure to ultraviolet (W) or electron beam radiation. Essentially no VOCs are emitted during curing, which is a major advantage of these types of coatings. Other advantages include very rapid curing, very little energy input, and the ability to collect and reuse overspray. However, system cleanup does involve the use of solvents.

Ultraviolet Curable Coatings

W curing uses high-intensity W light to initiate the free radical crosslinking of acrylate oligomers and prepolymers. UV curable coatings are limited to applications where coatings of roughly 200 microns or less are useful. The use of W coatings is limited to clear lacquers or semi- transparent applications. Some pigments, such as titanium dioxide, are

Metal Painting II-24 Altemate Fomwlatiom

I

EB coatings are thicker than W coatings; generally they 6 are limited to flat surfaces.

The EB p m s s Is relatively new, and installed systems are expensive.

strong absorbers of UV light and their use retards curing. UV coatings are used primarily on paper to achieve a high-gloss, transparent finish at curing times as fast as a fraction second. W coatings are also used on metal and plastics. UV curing of coatings is a line-of-sight process and is limited to flat surfaces, though in some instances three-dimensional objects have been W cured.

depending on the scope of the operation (Chemical and Engineering News 1991).

The cost of a W curing system will vary from $4,200 to $200,000

Electron-Beam Curable Coatings

Electron beam (EB) curable coatings offer an advantage over UV curable coatings in that thicker and more opaque coatings can be developed on a workpiece. EB curables utilize a monomer/prepolymer or a monomer/slightly polymerized mixture that is low in viscosity but contains no organic solvents. The coating cures (polymerizes) when exposed to a focused electron beam. Curing times are instantaneous, and almost no heat is generated in the item being coated. For high-gloss applications, time must be allotted after application to allow the coating or ink to flow out and level, before entering the instantaneous cure step.

Like the UV coatings, the electron-beam process is good for line- of-sight applications only, and is limited to flat surfaces. Stringent substrate surface preparation with iron phosphate, zinc phosphate, mag- nesium phosphate, or sulfuricboric acid anodizing is required. The EB process is relatively new and expensive. It has seen limited use in high- volume printing applications, and is also used on wood and plastic substrates. It also is used to finish automotive hubcaps and wheel rims.

$1 million mark (Chemical Engineering News 1991). A basic system costs $6OO,ooO; most systems installed approach the

Infrared Curable Coatings

IR curable coating systems may provide economic alternative.

Although electric infrared curable coatings have been commercial for over 50 years, only recently have they been improved sufficiently to warrant consideration. New coating systems can tolerate high levels of IR energy, and energy efficient IR emitters are available. According to the Electric Power Research Institute’s Center for Materials Fabrication, IR curable coatings are attractive for automotive, plastics, paper

Metal Painting II-25 Altotate Fwmulations

converting, graphics, packaging, textile and wood products industries (EPRI 1990). They are energy efficient, require less floor space than conventional heaters, provide prime control, and are flexible and adapt- able to many finishing lines. Their major drawback lies in the fact that with poorly conducting substrates (Le., wood, paper, and plastics), they are limited to flat surface which permit direct line of sight.

An IR oven that can heat a surface of 4 by 10 feet costs between $50,000 and $l00,OOO. Replacement IR emitters can cost up to $300,000 depending on size. Electric IR ovens are four times more efficient than convection ovens.

Metal Painring II-26 Altemate Formulations

I

F. CHECKLIST FOR USING ALTERNATE COATING FORMULATIONS

O

0

0

0

0

0

Will high solids coatings be a viable alternative for my operations?

Will water-based coatings provide a quality finish?

If so, will my product and finishing lines tolerate longer drying times, increased susceptibility to dirt pickup, and better temperaturehumidity control?

Will my product finishing requirements lend themselves to powder coatings?

Can I use electrostatic coating techniques?

Can I benefit from “next generation” coating systems, e.g., twocomponent reactive liquid, supercritical CO,, or radiation curable coatings?

/

Metal Painting II-27 Al tmte FomuJations

G. REFERENCES

Literature references cited in this section are listed below. Addi- tional sources of information are compiled in Section VI, Bibliography.

Bocci, Greg. 1991. Reprint from Product Finishing. Gardner Publications, Inc.

Chemical and Engineering News. 1991. “Higher Paint Sales Brighten Profits Outlook,” October 14, 1991, pp. 29-56.

EPRI Center for Materials Fabrication. 1990. “Infrared Processing of Coatings,” Tech Conmzentary, Vol. 3, No. 6, March 1990, pp. 1-4.

“Finishing Handbook and Directory.” 1991. Sawell Publications Ltd., by the Publisher of Product Finishing.

“Hazardous Waste Minimization Handbook.” 1989. Lewis Publishers, Inc., Thomas E. Higgins.

“Hazardous Waste Minimization - Industrial Overview.” No date. Pub- lished by the Air and Waste Management Association. Harry M. Freeman, editor.

ICF. 1989. New York State Waste Reduction Guidance Manual. Prepared by ICF Technology Incorporated for the New York State Department of Environmental Conservation. March 1989.

Industrial Extension Service, School of Engineering, North Carolina State University. 1984. “Managing and Recycling Solvents - North Carolina Practices, Facilities, and Regulations.” December 1984. pp. 46-47.

Levinson, S. B. 1988. “Application of Paints and Coatings.” Federation Series on Coatings Technology, Federation of Societies for Coatings Technology, August 1988.

Metal Painting 11-28 Altemate Fwmulations

“Metal Finishing Guidebook and Directory Issue ’91”. 1991.59th Guide- book and Directory Issue 1991. Metals and Plastics Publications, Inc. Volume 89, No. lA, Mid January, 1991.

U.S. EPA Guide to Application of Clean Technologies for Replacement Coating Materials, unpublished draft. Review draft dated January 10, 1992.

Walberg, k C. 1990. “Boost Overall Transfer Efficiency (High Solids),” Industrial Finishing, May 1990.

Metal Painting II-29 Altemate Formulations

SECTION III MORE EFFICIENT APPLICATION

Improved transfer Improvements in the efficiency of transfer of coatings to the work- efficiency reduces waste and solvent releases.

piece lead to less paint waste and lower emissions from the carrier solvent. The reason for this is that smaller quantities of paint need to be applied to get the required coverage, and overspray is reduced. The use of more efficient application methods saves on paint costs, VOC control costs, and hazardous paint waste disposal costs. The use of the air spray method is fast becoming obsolete because newer more efficient spraying methods are available. These include:

High-volume, low-pressure (HVLP) spray.

Airless and airless, air-assisted spray Electrostatic spray and air-assisted, electrostatic spray Electrostatic bells and high-speed disk spray

Before examining these methods, you should be aware of the more important factors in evaluating coating techniques and results.

Transfer Efficiency. Transfer efficiency is the term used to describe the relative volume of paint reaching the workpiece. It is the net amount of paint solids deposited on a part, divided by the total paints solids sprayed, expressed as a percentage. It is calculated using the formula:

TE = W p / % S x Q x T

where T E = w = Q = T =

%5 =

Transfer efficiency Weight of paint solids on the workpiece after baking Percent of paint sprayed that is solid Paint flow rate through the gun Time the paint is flowing (spraying time).

Typical paint spray efficiencies have been reported in the New York State Waste Reduction Guidance Manual (ICF 1989) and by A C. Walberg at Paint Con ’87 (1987). These are tabulated below as “NY Manual’’ and “Conference,” respectively.

Metal Painting III-1 Mom Efficient Application

Transfer Efficiency Smav Method NY Manual Conference

Conventional, air atomized 30 to 60% 25 %

Airless spray 65 to 70% 40% Air-assisted airless 40% High-volume, low-pressure (HVLP) 65 %

Electrostatic, air atomized Electrostatic, airless 70 to 95% 70% Electrostatic, rotating discs and bells 80 to 90% 85 %

60 to 70%

The wide range in quoted transfer efficiency is due to variations in the methods of measuring.

Some nonspray methods of applying coatings should be mentioned here for comparison sake. Electrocoating, described in the previous section, is 90 to 99 percent efficient in paint usage. This high efficiency is achieved because loose paint particles in the rinse water are recycled to the coating tank. Roll coating, which is usually used in continuous coating of coils of aluminum or steel, is reported to be 90 to 98 percent efficient in paint usage. Dip coating and flow coating are reported to have transfer efficiencies of roughly 90 percent.

Other factors, Unfortunately transfer efficiency is not a definitive term in the must be

considered when attempting to

real world of spray painting. Minimizing paint waste is not necessarily achieved by using the technique that has the highest rated transfer

improve transfer efficiencies.

efficiency. Other factors that must be considered include: Quality of finish Production rate

Desired film thickness Edge buildup Need for manual touchup

Uniformity of applied film thickness

Faraday cage effects (in electrostatic spraying). When comparing application techniques for possible use in your plant, you should consider spray efficiency and the above factors as part of the testing.

,, Metal Painting m-2 More Efficient Application

Transfer efficiency decreases as particle size decreases.

Transfer efficiency varies with production rate.

Desired versus applied thickness is a factor in transfer efficiency.

Uniformity of coating vanes with spray pattern.

Excess buildup and manual touchup affect real transfer efficiency.

Finish Quality. The quality of the finish is generally improved as spray particle size is reduced. Unfortunately, as spray particle size is decreased, transfer efficiency decreases. Some of the finest particle sizes are achieved with conventional air atomized spraying; however this is the least efficient means of applying paint. Customer finish requirements must be met; therefore, a compromise between transfer efficiency (paint savings) and quality must be achieved.

Production Rate. It is necessary to establish a desired production rate before determining a “transfer efficiency” for your application. The efficiency of spray devices will vary with the rate of application. This is especially true if coating is being done on a conveyerized system that includes other operations.

Film Thickness and Uniformity. The thickness of the applied film versus the thickness desired is important to establish when determining real transfer efficiency. If a 1-mil-thick film is specified, but the spray device can only deliver a quality film of 2 mils or greater, then at least SO percent of the paint is wasted. Thus, even if all of the paint used is applied to the workpiece, the real transfer efficiency is only 50 percent.

spray pattern can hold film thickness variations to 10 percent in a well engineered painting system. However, a round doughnut-shaped pattern is obtained in some systems. This type of spray pattern delivers a film thickness variation of about 1 mil. That is, if the desired film thickness is 1 mil, the coating can have areas that are 2 mils thick. The doughnut- shaped spray pattern can waste about 25 percent of the paint even when all the paint is applied. Thus, at best the real transfer efficiency is 75 percent.

Film uniformity also should be considered. A flat, fan-shaped

Other Issues. In electrostatic painting, edges normally attract paint spray that would normally pass by the workpiece. Paint builds up on the edges (edge buildup). This represents wasted paint even though it is transferred to the workpiece.

In recessed areas, the electrostatic field force limits the entry of paint particles. To achieve coating in the recessed area, overpainting of the nonrecessed area or manual touchup often is required. In this situation, real transfer efficiency is less than the quoted transfer efficiency.

The Faraday cage effect is encountered in electrostatic painting.

Metal Painting m-3 More Efficient Application

Conclusfons. The above discussion points out that the real transfer efficiency is dependent on your particular situation. Therefore, if you are considering a change in paint application methods to improve transfer efficiency, careful testing should be done to assure yourself that paint and solvent waste and coating use are truly being minimized.

A partial list of paint and coating equipment suppliers is given in Section V. Suppliers should be consulted. They will be able to assist in determining if a given application method is suitable for your operation.

Metal Painting III-4 M m Efficient Application

A. AIRLESS AND AIR-ASSISTED, AIRLESS SPRAY

Airless sprayhg Is more efficient than air spraying and handles relatively

Quality of thin coats, however, is not as good.

viscous coatings.

Air-assisted, airless spraying overcomes the quality disadvantages of airless spraying and also is more efficient.

1. Airless Spray Technique

In airless spraying, atomization is achieved by delivering high- pressure paint through a tiny shaped fluid orifice in the sprayer. Typical pressures used are between 1,OOO and 4,000 psi. When the pressurized paint enters the low pressure region in front of the gun, the sudden drop in pressure causes the paint to atomize. This process is analogous to water leaving a garden hose.

because the spray is softer and less turbulent, thus less paint is lost to “bounce back” and “glance off.” The droplets formed are generally larger than in the case of the air spray, and therefore a thicker coat of material can be applied in a single pass. Other advantages include the ability to utilize high-viscosity coatings (without thinning with solvents) and good penetration in recessed areas of the workpiece.

The major disadvantage of the airless spray is that the quality of the applied coating is not as good as in the case of air spray. However, this disadvantage disappears when thicker coatings are needed. Airless spray is often used when high-viscosity or highly pigmented paints are to be applied to surfaces where appearance is not critical. Sound deadeners and zinc-rich primers are examples of such use. Waterborne coatings may also be applied using the airless method.

The airless spray process is more efficient than the air spray

2. Alr-Assisted, Airless Spray Technique

Air-assisted, airless spray guns utilize the same airless principles addressed above. However, an air stream is used to improve atomization and for shaping the spray pattern. Thus, a shaped “soft” spray can be

formed and directed toward the workpiece. Paint cloud turbulence is reduced and less paint is wasted compared to the airless spray method. The use of the air assist improves the quality of the finish, presumably because finer paint particles are formed. The transfer efficiency of the airless, air-assisted spray gun is improved compared to that of the airless spray gun. The quality of finish obtainable is nearly as good as that obtained with air spray.

Mela1 Painting 111-5 More Efiient Application

B. ELECTROSTATIC SPRAY AND AIR-ASSISTED ELECTROSTATIC SPRAY

In electrostatic spraying the paint leaves the gun with an imposed electrical charge and is attracted to a workpiece that has an opposite electrical charge. Because of this electrical attraction of paint to the workpiece, transfer efficiencies are very high. In fact, paint may actually ”wrap around” to the backside of the workpiece. The electrostatic gun can be designed to operate with paint that is atomized by air, aiims, or rotational methods. The electric force field needed to guide paint particles to the workpiece is 8,000 to 10,OOO volts per inch of air between the gun and the workpiece.

Air and air-assisted electrostatic spray guns resemble nonelectro- Airless and air- static guns. The major difference is that an electrostatic gun has a wire charging electrode positioned in front to ionize the air. The ionized air

assisted, airless techniques can be used beneficially in electrostatic S P W W 3

passes its charge to the paint particles exiting the gun. Some guns have no external electrode, instead an internal electrode located inside the gun barrel is used to charge the paint. In another variation, a metal electrode is situated in the paint tank, and the paint is delivered to the gun already charged.

Some electrostatic spraying systems are air-assisted, airless in nature and are similar to the air-assisted, airless sprays, except that they are electrostatic. Figure III-1 presents schematic diagrams of typical setups for air spray electrostatic and airless electrostatic systems.

Metal Painting 111-6 Mow Emkn! Application

AIRLESS ELECTROSTATIC

I

Figure m-L Basic electrostatic spray equipment (Sames Electrostatic) (Levinson 1988).

1’

Metal Painting m-7 Mom Efficient Application

C. ELECTROSTATIC DISCS AND BELLS

To achieve greater transfer efficiencies and better finish, new electrostatic spray devices utilize rotating discs or bells. These devices have been described in recent publications, including the Metal Finish- ing Guidebook and Directory Issue ’91 (1991) and Finishing Handbook and Directory (1991). Some typical examples are shown in Figure 111-2.

In the spinning disc electrostatic method, paint is pumped to the center of the spinning disc, centrifugal force accelerates the particles to the outer periphery of the disc and into the air, causing atomization. This stream of charged paint particles is attracted to the oppositely charged workpiece.

Rotating discs or The principle behind spinning bell electrostatic painting is basically the same as the spinning disc method, except that compressed air is ejected from an annular ring that surrounds the bell. The air gives

efliciencies even more.

direction to the atomized paint mist, even though it will be electrostatically attracted to the workpiece. Adjustment of the annular compressed-air shroud can be made to vary the pattern of the spray. The spray pattern given off by the spinning bell method is doughnut-shaped.

Discs range up to 24 inches in diameter and bells up to 12 inches in diameter. Rotational speeds of up to 900 rpm or even as high as 60,000 rpm are utilized. The discs and bells are usually rotated by an air- driven turbine. The electrostatic units are usually charged to lo0,Ooo volts.

1. Use of Electrostatic Devices

Many of the disc and bell units are utilized in circular spray booths. The workpieces, attached to an overhead conveyer, enter the booth and circle around the electrostatic spray and exit. The spray units may move vertically to provide coverage for “high” workpieces.

The use of the disc is best for long, thin parts and flat stock. The rotating disc directs the horizontal spray in a thin, narrow plane and provides a fine, even coat. The doughnut-shaped paint cloud provided by the bell is better for coverage of shorter, wider parts.

Metal Painting m-8 More Efficient Application

C O ( J v E Y 0 A

ROTATOR

ATOMIZER DRIVE I

ELECTRO STATIC

Figure III-2. Typical disc and bell equipment (Paint Technology Manuals, London) (Levinson L988).

Metal Painting III-9 More Efficient Application

EleCtroStatiC spraying generally saves material and labor costs, and improves quality.

You need conductive workpieces, however.

2. Advantages and Disadvantages of Electrostatic Coating

The major advantages of using electrostatic spraying is the saving in coating material costs (high transfer efficiency) and labor. The labor saving is related to the usual use of electrostatics on automated lines, although in manual painting with electrostatics, cleanup labor is very minimal compared to conventional air spray. Other advantages of electrostatic coating include:

Complete coverage of odd shapes

Uniform paint thickness on level areas (this is due to the fact that the deposited paint electrically insulates the surface, causing further spray to be attracted to areas where little or no paint has reached.)

Coating of normally inaccessible areas.

Disadvantages of electrostatic coating include:

Limitation to coating only conductive surfaces (however, special conductive precoatings on nonconductive workpieces may be used to permit electrostatic coating)

Restriction of applying only one coat electrostatically, because the first coat acts as an insulator preventing a second coat

Difficulty in efficiently painting recesses such as internal corners and holes (electric fields known as Faraday cages prevent paint from giving good coverage, thus manual touchup is usually required)

Need for specially formulated paints capable of accepting an electrostatic charge

Problematic conductivity of waterborne paints, which makes them unusable unless special equipment modifications are made

Relatively high initial equipment costs and maintenance costs

Need for proper shock protection (on automatic paint lines this is less of an issue).

-

Metal Painting m-10 More Efiient Application

D. HIGH-VOLUME, LOW-PRESSURE (HVLP) SPRAY

Relatively high transfer efficiency also can be obtained with m X P spraying.

Low production rates and the need for low viscosity coatings are disadvantages.

Air spray systems can be readily converted by HVLS.

High-volume, low-pressure spray systems have been described in recent publications, including the Metal Finishing Guidebook and Direc- tory Issue ’91 (1991), Finishing Handbook and Directory (1991), Paint Con ’87 (Walberg 1987), and Fine Woodworking (Hostetter 1991; Dresdner 1991).

A n HVLP spray system is defined as an air spray system that operates at 10 psi or lower At these lower pressures, paint particles are propelled at lower velocities than in conventional air spray. At these lower velocities “bounce back” and “glance off“ of paint particles is minimized and transfer efficiencies are greater than those for conventional air spray systems. Although claims of very high transfer efficiencies have been made for the HVLP system, others claim that the best transfer efficiency obtained is equivalent to that of air-assisted airless sprays.

at the cost of lower fluid flow. Thus, the use of HVLP may not be a suitable substitute for air spray in high production rate situations. HVLP is a good method for applying low viscosity coatings and may be used with low solvent content coatings for minimizing VOC and toxic emissions. The finish achievable with HVLP can generally approach and compete with conventional air spray, when low to medium viscosity coatings are used.

The higher transfer efficiency obtainable with HVLP is achieved


Figure III-3 shows the schematics of the usual setups used with HVLP (low pressure) and conventional spray equipment. An air spray system can be converted to HVLP by retrofitting the air gun, installing larger diameter air hoses and an air regulator (to maintain pressures at 10 psi or lower). However air compressor capabilities may not be adequate. Usually 10 to 25 scfm of airflow are required. This translates into a need for a 3 to 10 hp compressor.

If you have a large investment in air compressors, conversion air systems (CAS) can be used. The CAS reduces high-pressure compressed air to low pressure and high volume. This can be done in two ways. First the conversion can be accomplished by using a CAS gun that is specially equipped to change from high to low pressure. These guns spray like HVLP guns, but connect directly to the high pressure compressed air

Metal Painting In-11 More Efficienr Application

CONVENTIONAL

LOW PRESSURE

COATING I I EX TRACTOR 4

TURBINE UOToR i PRESSURE TANK

Figure IlI3. Low pressure vs conventional spray equipment (Bessam-Aire).

source. Compressed air may be converted through use of a small CAS unit that attaches directly to the HVLP spray gun, or through use of a wall-mounted unit that takes in high pressure compressed air and provides an outlet for a HVLP hose.

2. Advantages and Disadvantages of HVLP

Advantages of HVLP include:

High transfer efficiency

0 Soft spray that penetrates easily into recesses and crevices

Reduced material consumption

Reduced VOC and toxic material emission.

Metal Painring In-12 More EfFcient Application

Disadvantages of HVLP include:

Potential reduction in surface finish quality

Possible need for relatively expensive turbine-generated systems

Need for a supply of clean dry air for efficient operation

Low production rates.

Metal Painring III-13 M m Efficient Application

E. CHECKLIST FOR MORE EFFICIENT APPLICATION

Will I improve transfer efficiencies by using airless, electrostatic, and/or HVLP spray techniques?

Will I maintain finish quality, production rate, and film uniformity and still improve transfer efficiencies?

Metal Painting 111-14 Mom Emient Application

F. REFERENCES


The DeVilbiss Company. 1989. “High Volume Low Pressure (HVLP),” Brochure, 1989.

Dresdner, M. 1991. “Conversion Air Systems: HVLP Performance With a Standard Air Compressor.” Fine Woodworking. SeptemberDctober 1991, pp. 68-69.


Hostetter, P. 1991. “Turbine Spray Systems -A High-Volume, Low- Pressure Finishing Alternative.” Fine Woodworking. September/October 1991, pp. 66-69.


Levinson, S . B. 1988. “Application of Paints and Coatings.” Federation Series on Coatings Technology, Federation of Societies for Coatings Technology, August 1988.

“Metal Finishing Guidebook and Directory Issue ’91”. 1991. 59th Guide- book and Directory Issue 1991. Metals and Plastics Publications, Inc. Volume 89, No. lA, Mid January, 1991.

Robinson, F. and Stephens, D. 1990. “Understanding Electrostatic Finishing,” Industrid Finishing, September 1990.

Walberg, A. C. 1987. “Transfer Efficiency,” presented at Paint Con ’87, March 31 -April 2, 1987, O’Hare Exposition Center, Chicago, Illinois.

Metal Painting HI-15 Mow EfFcient Application

SECTION IV MINIMIZING WASTE THROUGH IMPROVED OPERATIONS

Aside from use of more environmentally safe coatings and more efficient means of applying these coatings, there are other techniques available to minimize waste losses and VOC emissions. Below some of Good housekeeping

and manufacturing practices can also the major areas of note are addressed.

minimize waste and VOC emissions. A. DIRECT TRANSFER OF PAINT TO THE GUNS

Direct transfer of paint is a technique described in the recent literature, especially the Finishing Handbook and Directory, 1991. In transferring paints from storage to the guns, waste and emissions can be minimized by using a paint circulation system or direct transfer. A direct transfer system offers economy, safety, productivity improvement, and better finish quality. It is likely that direct transfer can be economically justified if as little as 30 to 40 gallons per week of a single color is used in your shop. The savings generated by installing direct transfer will pay for installation costs in about a year. The savings are generated by:

Direct transfer saves operating costs, time, and cleanup costs as well as minimizing waste and solvent releases.

I

Buying in bulk quantities (larger discounts)

Elimination of the need for filling a can from the drum

Elimination of spilling, evaporation, and loss of skimmings on the side of the drum

Elimination of labor needed to fi l l pressure pots, gravity con- tainers, or cups

Elimination of the time required to collect paint from the paint storage area

Elimination of time spent in adjusting paint to the correct viscosity (or adjusting for incorrect viscosity)

Elimination of container cleaning at the end of the shift.

Direct transfer does not merely increase productivity, it provides a method of attaining consistent quality in the paint reaching the guns. There are three general types of paint transfer systems:

Metal Painting rv-1 Minimizing Waste

Dead end Simple flow Fully recirculating.

The dead-end system is not a circulating system; it merely pushes paint out to the point of use and there is no return line. The dead-end system is useful for coatings that are completely stable and where there is no possibility of settlement. It is not suitable for pigmented coating materials.

The most widely used direct transfer system is the simple flow and return type. The return line is taken from the farthest point of use and returned to the storage tank. The continual circulation prevents settling and is suitable for most pigmented coating materials.

in the hose of the spray gun. A fully recirculating system is used only when high settlement rates are encountered, for example, in the use of acrylic lacquers by the automotive industry.

Usually nonpigmented material is pumped directly from the shipping drum. Pigmented materials may be pumped directly from the shipping drum if a specially built drum cover with built-in pump and agitator is utilized. If spraying viscosity adjustment is necessary, it is preferable to use a mix tank that has facilities for adding solvent.

In a fully recirculating transfer system the paint is circulating even

~~

Metal Painting rv-2 Minimizing Waste

B. HEATEDSPRAY

Heating the paint also lowers waste and VOC emissions.

Heated paint may be used with air spray, airless, or electrostatic equipment.

Heating offers no advantage for waterborne or spirit stains.' ,

1

Heated spray is a technique described in the recent literature, especially the Finishing Handbook and Directory (1991) and Levinson (1988). The use of heated paint for spraying lowers waste and emissions in several ways:

Heated paint has lower viscosity, and permits the use of less solvent; therefore, you pay less for solvent and there are less VOC emissions and less toxics to be concerned about.

Heated spraying at lower viscosity lowers the air pressure required to propel the paint (this is true for both air spray and airless spray). The use of lower pressures yields less overspray and gives higher transfer efficiencies. The net result is that less paint is needed to do the same job, and VOCs and toxics are minimized.

The use of lower pressure will also lower your power (electric- ity) costs, especially in multigun plants.

1. Effective Applications

Table IV-1 illustrates the effect of heating on paint viscosity, pressure energy, and overspray for both conventional air spray and airless spray conditions. Heated paint may also be used for electrostatic applications. If high solids coatings are being used, heating of the paint may be a requirement to lower viscosity for proper application. Field tests directly comparing cold air spraying with heated paint sprayed at lower pressures have shown that paint costs can be cut by 25 percent or more. No advantage, however, is gained from heating waterborne coatings or spirit stains.

you wish to consider a heated paint system, you should contact both your coatings supplier and your equipment supplier to determine the system most suitable for your production setup. A partial list of suppliers is presented in Section V if you should need other sources of information.

A variety of methods is available for heating paint for spraying. If

Metal Painting Iv-3 Minimking W a t e

Table IV-L The effect of preheating on paint viscosity.

Method

Air spray

Conventional

Heated

Airless spray

Conventional

Heated

Paint Viscosity Paint Temperature Pressure E n e d

70 F 150 F atGun Surface atGun Req. Overspray

(sew' ( s a ) (F) (F) @si) (Hp)

25 -- 70 55 80 9 Considerable

150 2.5 150 70 50 6 Moderate

25 -- 70 60 1500 1 Slight

150 25 150 75 500 03 Negligible

(a) No. 4 Ford Cup. @) Req. = required; psi = pounds per sq. in.; HP = horsepower.

Source: Levinson 1988.

2. Aerosols Maintenance and Touchup

Hand pump spray Using hand pump spray bottles (reusable) will cut down on VOC - _ _ _ bottles Offer better transfer efficiency for touchup,

emission and hazardous waste disposal by as much as 50 percent. The volume of paint is reduced through better transfer efficiencies. Hand

cleanup. pump spray bottles are best for cleaning and coating small surface areas that have corroded.

3. Advantages and Disadvantages of Heated Spray Systems

Preheated spraying results in a number of possible advantages; many yield higher production rates and lower VOC and toxic release problems. These advantages include:

0 Lowering of paint costs.

Elimination of the thinning operation.

About 25 percent increased coverage.

Metal Painting Iv-4 Minimiring Waste

Increased paint film thickness per coat.

Faster drying of applied paint.

Spraying at lower ambient temperatures and higher humidity conditions (eliminates the need for temperature and humidity control for unheated spraying when weather conditions are poor).

Improved coverage of porous and rough surfaces, smoother paint film and improved adhesion.

Disadvantages of heated spray are few:

More cumbersome equipment.

Need for additional capital investment.

Metal Painting Iv-5 Minimiring Waste

C. REUSE OR RECYCLING OF WASTE SOLVENTS

Reclaiming solvent can reduce waste management and raw material costs.

Spent cleaning solvent can be reused after the paint residue settles out.

Spent cleaning solvents can be distilled and RUSt?d.

Reuse and recycling techniques are described in the recent literature, especially in “Small Solvent Recovery Systems” (North Carolina Department of Environment, Health and Natural Resources 1987) and “Managing and Recycling Solvents” (Kohl et al. 1984).

1. Techniques for Reusing Waste Solvents

Cleanup solvents may be reused many times. The cleanup solvent can simply be left to settle in the spent solvent container. After an appropriate length of time, the paint residue will settle on the bottom of the container and the clear, “cleaner” solvent from the top can be reused for cleaning. During the settling period the container should be properly covered to prevent solvent evaporation and/or possible combustion. If more than one cleanup solvent is used, of course, the spent solvents should be properly segregated to permit efficient reuse.

2. Techniques for Recycling Waste Solvents

Solvents used in cleaning paint lines and paint guns can constitute a significant hazardous waste stream. These spent solvents must be disposed of properly or sent to a recycling operator. The best solution for handling spent solvents is in-house recycling. Commercially available stills capable of handling 0.5 to 100 gallons per hour can be purchased. The smaller units are self-contained, off-the-shelf items that can be readily installed. The usual utility requirements are electrical power and cooling water; some stills may require compressed air. The cost of purchasing a recycling still can be offset by savings on hazardous waste disposal costs and lower purchase needs for solvent.

solvent. If more than one is used, it is usually best to keep them separate. Mixed spent solvents may be amenable to distillation if they have boiling points that are similar; however, you must then be sure that the distilled mixture is suitable for reuse in your cleaning procedures. For solvents with boiling points below 200 F a simple still can be used. If the solvent you are using has a boiling point above 200 F, then a vacuum still is required. Vacuum stills are slightly more complicated to run and are more expensive.

To take full advantage of a still, you should use only one cleaning

Metal Painting IV-6 Minhizing Waste

Before purchasing a still, it is appropriate to have the supplier distill a sample of your waste so that you can evaluate the quality of the distilled product in your cleaning process. Also the trial distillation can be used to evaluate the percentage of spent solvent that can be recovered. This will allow you to estimate the savings you might achieve through lower fresh solvent costs.

Still bottoms Use of a still will eliminate most of your waste solvent disposal costs; however, the still bottoms will usually be hazardous waste that must be disposed of properly. The cost of waste disposal may be avoided

usually are a hazardous waste. They may be mused to make -paint. if you can find a use for the bottoms. In a previously cited case study

(Great Dane Trailers), the still bottoms were mixed with black pigment, oils, and hardeners to produce an undercoat paint. This may be possible at your plant if you have a need for undercoating o r painting items primarily for protection where color is not important. To determine if your still bottoms may be used in this fashion, it is necessary to work with your coatings supplier to determine your options.

I

Metal Painting Iv-7 Minimizing Waste

Inventory control, standardization of paints, better scheduling, and proper operator training also can minimize waste and toxic releases and reduce costs.

D. OTHER OPERATING PRACTICES FOR WASTE MINIMUATION

The recent literature, especially “Waste Reduction Options: Paint- ing” (Georgia Tech Research Institute 1991) and the New York State Waste Reduction Manual (ICF 1989), decribes practices that can help minimize paint waste. These include inventory control, standardization of paints, improved scheduling, equipment maintenance, and proper training of spray system operators.

1, Inventory Control

An inventory control and tracking system should be utilized to minimize paint sludge generated by paints left unused in storage. In some cases paint is left unused because workers are unaware that it is in stock. In other cases, paints are overordered. A n inventory control and tracking system will also help you consolidate paint usage so that purchases of paint can be made in bulk. On the other hand, you should only order as much paint as is needed, even if i t means foregoing discounts available on larger lots. Remember that the waste disposal costs must be considered, once the shelf life is exceeded.

A number of storage and transfer practices should be practiced to minimize waste. These include:

Checking drums for leaks.

Storing drums near areas where they are used to reduce leaks and spills during transport.

Using spigots or pumps to dispense new materials, and using funnels to transfer waste materials; these practices will avoid leaks and spills.

Installing tight-fitting lids and spigots to reduce evaporation.

Lifting drums with powered equipment or hand trucks to prevent damage or puncture.

2. Standardization of Paints

Customer requirements should be reviewed with thought of possible standardization. If you have two customers using a somewhat similar color and in the same type of paint, you may be able to get one to

Metal Painting rv-8 Minimizing Wate

change to another color. Or you may get both to change to a common color. This can lead to less leftover paint and less waste. Additionally, it may allow you to order in larger quantities at a greater discount. (Another benefit could be less gun and line cleanup, if the customer’s jobs can be scheduled sequentially.)

3. Improved Scheduling

Scheduling of paint spray jobs from light to dark colors can reduce wastes generated in equipment cleanup. Scheduling to permit the end-of-day cleanup to coincide with the end of a job can eliminate a cleanup procedure and eliminate the waste from one cleanup.

4. Proper Training of Personnel

Proper spray techniques must be practiced by the spray gun operator. Training videos are available (some are referenced in Section VII of this manual). Obviously the use of techniques that minimize overspray and control the spray overlap, etc., can minimize paint waste and should be monitored closely. Proper gun cleaning techniques are important also. For example, guns should be cleaned before paint sets up. Non- chlorinated solvents can be used for cleaning up gates.

Metal Painting Iv-9 Minimiting Waste

E. CHECKLIST FOR IMPROVED OPERATIONS

Will I significantly reduce waste by direct transfer of paint to the guns?

Will I use heated spray techniques?

Will I improve operations by reusing or recycling any waste solvents?

WiIl I improve operations by better inventory control, standardization of paints, improved scheduling, and proper training of personnel in spray and gun cleaning/maintenance techniques?

Metal Painting Iv-10 Minimizing Waste

F. REFERENCES



Georgia Tech Research Institute. 1991. “Waste Reduction Options: Painting.” Guide No. 5, Spring 1991.

ICF. 1989. New York State Waste Reduction Guidance Manual. Pre- pared by ICF Technology Incorporated for the New York State Depart- ment of Environmental Conservation. March 1989.

Kohl, Jerome; Moses, Philip; and Triplett, Brook. 1984. “Managing and Recycling Solvents.” North Carolina Practices, Facilities and Regulations. December 1984.


North Carolina Department of Environment, Health and Natural Resources. 1987. “Small Solvent Recovery Systems.” Pollution Pre- ventiun Tips, Pollution Prevention Program, North Carolina Depart- ment of Environment, Health and Natural Resources. March 1987.

Metal Painting rv-11 Minimizing Wmte

SECTION V SUPPLIERS

Some Sources of Coatings and Application Equipment

Electrostatic Painting Equipment

Binks Mfg. Corp. 9201 W. Belmont Ave. Franklin Park, IL 60131 (708) 671-3000

DeVilbiss Co. 300 Phillips Ave. Toledo, OH 43601 (419) 470-2169 (800) 338-4448

Electrostatic Components 955 Connecticut Ave. Bridgeport, CT 06607 (203) 366-3398

Gram, Inc. P.O. Box 1441 Minneapolis, MN 55440 (612) 623-6000 (800) 328-0211

Nordson G x p . 555 Jackson St. Amherst, O H 44001 (216) 988-9411 (800) 621-6413

Ransberg Gema, Inc. P.O. Box 88220 Indianapolis, IN 46208 (317) 298-5000

Wagner Spray Technology Corp. 1770 Fernbrook Lane Minneapolis, MN 55441 (612) 553-7000 (800) 328-8251

Spray Paint Spraying Equipment and Supplies

Accuspray Division Bessam Aire Inc. P.O. Box 391525 26881 Cannon Rd. Cleveland, OH 44139 (216) 439-1200 (800) 321-5992

Atlas C o p , Finishing Division 24404 Indoplex Circle Farmington Hills, MI 48018 (313) 478-5330 (800) 521-4522

Binks Mfg. Corp. 9201 W. Belmont Ave. Franklin Park, E 60131 (708) 671-3000




Metal Painting v- 1 Supplien

I ,

I '

Nordson Corp. 555 Jackson St. Amherst, OH 44001 (216) 988-9411 (800) 621-6413



Powder Coatings Equipment and Systems

Advanced Powder Coatings Inc. Stone Hill Rd. RD#1 Denver, PA 17517 (215) 484-4789

Belco Industries, Inc. 115 E. Main St. Belding, MI 48809 (616) 794-0410

DeVilbiss Co. 300 Phillips Ave. Toledo, OH 43601

(800) 338-4448 (419) 470-2169


Nordson Corp. 555 Jackson St. Amherst, OH 44001 (216) 988-9411 (800) 621-6413


Voltstatic Corp. 7960 Kentucky Dr. Florence, KY 41042 (606) 371-2557

HVLP Systems

Accuspray Division Bessam Aire Inc. P.O. Box 391525 26881 Cannon Rd. Cleveland, OH 44139 (216) 439-1200 (800) 321-5992

American Spray Industries 221 S. State St. P.O. Box 86 Harrison, OH 45030 (812) 637-3215 (800) 443-4500

Apollo Sprayers International,

1030 Joshua Way Vista, CA 92083

Inc.

(619) 727-8300

Binks Mfg. Co. 9201 W. Belmont Ave. Franklin Park, IL 60131 (708) 671-3000

Croix Air Products, Inc. 520 Airport Rd. Fleming Field South St. Paul, MN 55075 (612) 455-1213


Metal Painting v-2 suppliers


Hood Products Eagle Spray-Kace Technologies

P.O. Box 513 Milltown, NJ 08850

Inc.

(908) 651-1555 (800) 966-5223

Lex-Aire Spray Systems 34 Hutchinson Road Arlington, MA 02174 (617) 646-1102 (800) 537-2473


Paint, Primer & Solvent Suppliers

Akzo Coatings America, Inc. P.O. Box 7062 Troy, MI 48007 (313) 637-0400

DeSoto, Inc. 2121 New World Drive Columbus, OH 43204 (614) 497-6524

DuPont Co. 1007 Market St. Wilmington, DE 19898 (800) 441-7515

Fuller Co., H. B. 3200 Labore Rd. Vadnais Heights, MN 55110 (612) 481-9558

Glidden Industrial Coatings 925 Euclid Ave. Cleveland, OH 44115 (216) 344-8000

Guardsman Chemicals, Inc. 2960 Lucerne S.E. Grand Rapids, MI 49501 (616) 957-2600

IC1 Resins USA, Inc. 730 Main St. Wilmington, MA 01887 (617) 658-6600

PPG Industries 1 Gateway Center Pittsburgh, PA 15222 (412) 434-3131 (800) 243-6774

Pratt & Lambert, Inc. 40 Sonwil Drive Cheektowaga, NY 14225 (716) 683-6831

Sherwin-Williams Co. 11541 S. Champlain Ave. Chicago, IL 60628 (312) 821-3000 (800) 821-3800

Volspar Corp. 1101 3rd St. South Minneapolis, MN 55415 (612) 333-7371 (800) 328-8044

Powder Coating Materials

Dow Chemical Co. 2020 Willard H. Dow Center Midland, MI 48640 (517) 636-0339 (800) 258-2436

,/'

Metal Painting v-3 Suppliers

DuPont Co. 1007 Market St. Wilmington, DE 19898 (800) 441-7515

Evteck, A Kodak Co. 9103 Forsyth Park Dr. Charlotte, NC 28241 (704) 588-2112 (800) 333-8236

Ferro Corp. lo00 Lakeside Dr. Cleveland, OH 44114 (216) 641-8580

Fuller Co., H. B. 3200 Labore Rd. Vadnais Heights, MN 55110 (612) 481-9558

Glidden Industrial Coatings 925 Euclid Ave. Cleveland, OH 44115 (216) 344-8000

Lilly Powder Coating Inc. P.O. Box 414620 1136 Fayette N. Kansas City, MO 64141 (816) 421-7400

Morton International, Inc.

Reading, PA 19612 P.O. Box 1-5240

(215) 775-6600

Pratt & Lambert, Inc. 40 Sonwil Dr. Cheektowaga, NY 14225 (716) 683-6831

~~~ __ Metal Painting v-4 supprim

SECTION VI BIBLIOGRAPHY

This section contains a compiled listing off all literature sources referenced in this document.

Bocci, Greg. 1991. Reprint from Products Finishing, Gardner Publica- tions, Inc.

Chemical and Engineering News. 1991. “Higher Paint Sales Brighten Profits Outlook,” October 14, 1991, pp. 29-56.

The DeVilbiss Company. 1989. “High Volume Low Pressure (HVLP),” Brochure, 1989.

Dresdner, M. 1991. “Conversion Air Systems: HVLP Performance With a Standard Air Compressor.” Fine Woodworking. September/October 1991, pp. 68-69.

EPRI Center for Materials Fabrication. 1990. “Infrared Processing of Coatings,” Tech Commentary, Vol. 3, No. 6, March 1990, pp. 1-4.



Georgia Tech Research Institute. 1991. “Waste Reduction Options: Painting.” Guide No. 5, Spring 1991.

“Hazardous Waste Minimization Handbook.” 1989. Lewis Publishers, Inc., Thomas E. Higgins.

“Hazardous Waste Minimization -Industrial Overview.” No date. Pub- lished by the Air and Waste Management Association, Harry M. Freeman, editor.

/

Metal Painting VI- 1 Biblwgmphy

Hostetter, P. 1991. “Turbine Spray Systems- A High-Volume, Low- Pressure Finishing Alternative.” Fine Woodworking. September/October 1991, pp. 66-69.

Industrial Extension Service, School of Engineering, North Carolina State University. 1984. “Managing and Recycling Solvents -North Carolina Practices, Facilities, and Regulations.” December 1984. pp. 46-47.

Kohl, Jerome; Moses, Philip; and Triplett, Brook. 1984. “Managing and Recycling Solvents.” North Carolina Practices, Facilities and Regulations. December 1984.


“Metal Finishing Guidebook and Directory Issue ’91”. 1991.59th Guide-

book and Directory Issue 1991. Metals and Plastics Publications, Inc. Volume 89, No. lA, Mid January, 1991.

North Carolina Department of Environment, Health and Natural Resources. 1987. “Small Solvent Recovery Systems.” Pollution Prevention Tips, Pollution Prevention Program, North Carolina Department of Envi- ronment, Health and Natural Resources. March 1987.

U.S. EPA Guide to Application of Clean Technologies for Replacement Coating Materials, unpublished draft. Review draft dated January 10, 1992.

Robinson, F. and Stephens, D. 1990. “Understanding Electrostatic Finishing, Industrial Finishing, September 1990.

Walberg, A. C. 1987. “Transfer Efficiency,” presented at Paint Con ’87, March 31 -April 2, 1987, O’Hare Exposition Center, Chicago, Illinois.

Metal Painting VI-2 BibIiogmphy

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