TIPS: Coatings

TIPS: Pollution Prevention Guide for
Surface Coating Operations

[ Equipment ][ Coatings ][ Application ][ Clean-Up ][ Inventory ][ Coatings Removal ]
[ Removal Options; Blasting ][ Removal Options; Non-Blasting ][ Recycling and Reusing Blast Media ]
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EQUIPMENT

Use high volume low pressure (HVLP) paint spray guns instead of conventional spray guns. Benefits include higher efficiency, reduced overspray, lower booth maintenance and less cost associated with paint related waste. (May be required in ozone nonattainment areas)
Use enclosed gun wash units to clean paint equipment. Benefits include reducing the amount of thinner used by more than 50 percent and reduced labor time for cleaning.
Install a solvent distillation unit in order to reuse solvent and reduce hazardous waste.
Consider changing to electrostatic coating equipment to improve transfer efficiency, reduce costs associated with new coating purchase, and reduce the time required to apply the coating.
Consider installation of a proportioner on the spray equipment for plural component coatings such as epoxies and polyurethanes. The proportioner mixes the paint as it is used; therefore, waste associated with unused paint may be reduced.

COATINGS

Use high solid/low volatile organic compound (VOC) coatings (required in ozone nonattainment areas).
Consider waterbased coatings to minimize emissions.
Consider powder, ultraviolet cured, or electric ion beam coatings.

APPLICATION

Consider eliminating coatings all together or using precoated steel if available.
Prior to an actual coating application, perform a "dry run," which allows the technician to identify problem areas and ensure proper gun clearance is maintained during the actual procedure.
Use suggested air pressure and tip sizes for the specific product and equipment being used.
Always hold the gun perpendicular to the surface being sprayed, using parallel strokes.
When painting small- and medium-sized panels, make each pass the full length of the panel.
Use a 50 percent overlap for each pass.
Feather the trigger at the beginning and end of each pass.
With larger panels, walk the full length when possible. Otherwise use a comfortable stroke with a 4 to 5 inch stroke overlap.
Spray the border edges of the substrate first (banding). This will assure all edges are covered without extending the spray pattern well beyond the borders of the object.
Use color hiding power labels to determine when adequate coverage has been achieved. Use mil thickness gages to determine the thickness of the coating applied.
Consider paint mixing systems, which can increase productivity and reduce material costs.
When mixing paint colors, only mix the amount of color needed for that specific job.

CLEAN-UP

Consider using an aqueous based solvent for degreasing and cleaning prior to coating.
Save clean-up solvent to use later as thinner for paint of the same color.

INVENTORY

Buy quantities of coating and solvents that can be utilized within a reasonable period of time to prevent the products from expiring on the shelf.
Return expired coating and solvent to the distributor or manufacturer instead of disposing as a waste.

TIPS: Pollution Prevention Guide for
Surface Coating Operations

REMOVAL OPTIONS (Blasting)

Plastic blasting media is a nonhazardous alternative to methylene chloride coating stripper. The media is projected at a surface to gently remove coating without damaging the underlying metal. Plastic blast media can be reused until the particles are broken down too small to be effective. The resulting dust may be picked up from your facility and recycled into counter and table tops.
A dry ice (carbon dioxide) system can quickly remove surface coatings without damaging the item being cleared, and eliminates the use of hazardous solvents. Propelled by nitrogen gas or compressed air, dry ice disappears as carbon dioxide gas leaving a relatively small waste stream. This economical process can replace many harsh chemical processes, can be used on delicate components, and may strip difficult or impossible to clean equipment.
Sodium bicarbonate (baking soda) blasting is a nonhazardous alternative to coating removal carcinogenic chemicals such as methylene chloride. By controlling the particle size and ration of water in the blast stream, the abrasiveness of the blast can be adjusted to strip delicate components or impossible to clean equipment. The minimal amount of solid residue can be filtered from the water-soluble waste and land-filled.

REMOVAL OPTIONS (Non-blasting)

Consider a vacuum orbital sander that eliminates hazardous particles as it removes surface coatings. A vacuum draws materials through a series of high efficiency filters and eliminates the need to wear a respirator.
Water-based coating removers are a safe alternative to methylene chloride. Benefits include lower operating costs, decreased air pollution and effluent water, and zero possibility of mechanical damage to substrate.

RECYCLING AND REUSING BLAST MEDIA

High temperature waste vitrification is a new process that converts sandblasting residues into a glass, foam glass, glass bead, or abrasive blast media. The metals from the residue provide color and structure, as well as other properties to the final product. The generated product is inert, nonhazardous, reusable, and passes toxic characteristic leachability tests (TCLP). This unit is typically installed within a facility and would require a fairly large volume of blast residue.

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