Collision Repair - Solvent and Paint-contaminated Waste 11-1 (a) Wastes Associated with Automotive Painting n Waste paint (old, leftover, dried etc.) n Solvent (various types) n All materials contaminated with paint including: –Used paint booth arrestors (also called exhaust filters) –Disposable rags

Collision Repair - Solvent and Paint-contaminated Waste 11-1 (b) Wastes Associated with Automotive Painting –Masking tape and paper –Floor sweepings –Disposable mixing cups and sticks –Disposable paint strainers

Collision Repair - Solvent and Paint-contaminated Waste 11-2 (a) Minimize the Amount of Painting Waste n Use reusable mixing cups and sticks –Clean them in a mechanical gun wash system. n Use cloth rags that are cleaned by a laundry service and returned. n Improve transfer efficiency of coating operations. n Recycle solvent on-site with a solvent distillation unit.

Collision Repair - Solvent and Paint-contaminated Waste 11-1 (b) Minimize the Amount of Painting Waste n Recycle solvent off-site - recycling service. n Prevent solvent evaporation - close lids. n Use a mechanical gun wash system to reduce solvent waste. n Keep records of the types and quantities of materials used to better estimate future jobs. n Use a material usage tracking form.

Collision Repair - Solvent and Paint-contaminated Waste 11-3 Minimize the Hazardous Nature of Paint-Related Waste n Use undercoats and topcoats that contain no heavy metals. –Arsenic, barium, cadmium, chromium, lead, mercury, selenium, and silver. n Use low-VOC paint and solvent products. n Use water-based coatings when practical.

Collision Repair - Solvent and Paint-contaminated Waste 11-4 (a) Disposal of Paint-Related Wastes n Liquid paint and solvent waste –Managed as a hazardous waste. –Stored in sealed containers labeled “Hazardous Waste ”. –Disposal by a hazardous waste management company.

Collision Repair - Solvent and Paint-contaminated Waste 11-4 (b) Disposal of Paint-Related Wastes n Dry paint-related wastes: paint booth arrestors, rags, floor sweepings, masking tape etc... –Potentially hazardous due to metals, solvents and must be laboratory tested. –If hazardous, must be managed same as liquid paint and solvent wastes –If nonhazardous may landfill with approval and permits.

Collision Repair - Solvent and Paint-contaminated Waste 11-5 (a) Transfer Efficiency n Transfer Efficiency (TE) is the ratio of the mass of solids (in the paint) reaching the surface being coated, to the mass of solids sprayed. n Transfer Efficiency = (Mass of Coating [Solids] Sprayed - Mass of Coating [Solids] Applied).

Collision Repair - Solvent and Paint-contaminated Waste 11-5 (b) Transfer Efficiency n High transfer efficiency means less paint is wasted in overspray. n Poor transfer efficiency causes excessive paint and solvent waste.

Collision Repair - Solvent and Paint-contaminated Waste 11-6 (a) Factors Affecting Transfer Efficiency n Factors that cannot be controlled by the spray operator. –Size and shape of the parts sprayed. –Atmospheric conditions –Finish quality requirements.

Collision Repair - Solvent and Paint-contaminated Waste 11-6 (b) Factors Affecting Transfer Efficiency n Factors that can be controlled by the spray operator: –Spray equipment type –Gun set up –Spray angle –Spray distance –Spray techniques –Spray equipment maintenance and practices

Collision Repair - Solvent and Paint-contaminated Waste 11-7 (a) Improving Spray Technique n Operator spray technique is the most important element in achieving a good transfer efficiency. n Spray Angle –Gun perpendicular to the surface being sprayed –Use parallel strokes. –Never arc the gun »except when performing blending operations or panel spotting.

Collision Repair - Solvent and Paint-contaminated Waste 11-7 (b) Improving Spray Technique n Spray Pattern. –Uniform pattern –Coating must be atomized properly. n Spray Distance –Appropriate distance from the surface being sprayed. »6 to 8 inches (as close as 4 in. with some gun/coating combinations) »Distance constant throughout the coating operation.

Collision Repair - Solvent and Paint-contaminated Waste 11-7 (c) Improving Spray Technique n Spray Overlap –50 per cent overlap for each pass –Feathering the trigger at the beginning and end of each pass. » Note: Technique may be altered slightly when applying high metallic, high solids base coats and some three stage systems

Collision Repair - Solvent and Paint-contaminated Waste 11-7 (d) Improving Spray Technique n General Spray Techniques –Have a “plan of attack” –Do a “dry run” to practice spraying strategy. –For small and medium sized panels - make each pass the full length of the panel. –Spray larger panels in the same way, walking the length of the panel.

Collision Repair - Solvent and Paint-contaminated Waste 11-7 (e) Improving Spray Technique –Keep blended areas as small as possible. –Spray the border edges of the substrate first (banding). n High Transfer Efficiency Spray Equipment –HVLP gun uses high-volume/low pressure –LPLV gun uses low pressure/low volume

Collision Repair - Solvent and Paint-contaminated Waste 11-7 (f) Improving Spray Technique n Choose the Best Equipment You Can Afford ! –Equipment budget. –Coating types being sprayed. –Ask paint representative for assistance. –Choose spray equipment for highest transfer efficiency and proper atomization.

Collision Repair - Solvent and Paint-contaminated Waste 11-7 (g) Improving Spray Technique –Use the proper fluid tip/air cap combination and gun settings for the material being sprayed. –Remember >>> A paint gun is only as good as the operator using it !!!!! n Gun Set-up –Correct size of fluid tip-air cap combination. »Fluid tip size is determined by coating viscosity »Viscosity is measured by a Zahn cup measuring system.

Collision Repair - Solvent and Paint-contaminated Waste 11-7 (h) Improving Spray Technique –Choice of air cap depends of the fluid tip size »Ask spray gun manufacturers for recommendations –Set the air pressure at the lowest possible setting. »Never exceed the coating manufacturer's recommended air pressure settings. –Keep records of gun set ups used with each type of coating to reduce set up time and material wasted during set up.

Collision Repair - Solvent and Paint-contaminated Waste 11-7 (i) Improving Spray Technique n Spray Equipment Maintenance –Maintaining clean equipment clean in good working order ensures proper atomization and a full, consistent spray pattern.