Waterborne automotive paints have replaced solvent-based materials in most body shops as a means of reducing emissions of volatile organic compounds. Although waterborne products have a number of limitations during the application process, they can achieve excellent color matches, invisible blended repairs and strong metallic content. Waterborne paints are largely used to add color; waterborne clear coats are also available. However, the automotive repair sector still relies largely on the use of urethane clear coats which have a lower VOC content than acrylic alternatives. Waterborne paints differ from water-based products because they cannot be redissolved once the curing process is complete.
Things You'll Need
- Lint-free cloth
- Compatible degreaser
- Waterborne paint tack cloth
- Waterborne paint
- Paint strainer
- High volume, low pressure (HVLP) spray gun
- Air compressor
- Air-fed blowing unit
- Compatible clear coat
Carry out a visual inspection of the panel surfaces to ensure preparation is correct. Apply a small quantity of compatible degreaser to a piece of lint-free cloth and wipe down each individual panel thoroughly before using a clean piece of cloth to dry any residue. Remove traces of hair, dust and fibers by wiping over each panel with a tack cloth that is specifically designed for use with waterborne products.
Thin the waterborne paint with a compatible activator using the ratio provided on the technical data sheet. Most modern products require only 10 percent of activator but colors with poor opacity can be thinned to a ratio of 5 percent. Pour the activated material through a strainer into the pot of a gravity-fed HVLP spray gun with a fluid tip setup of 1.2 mm.
Plug the HVLP spray gun into an air line and hold it out at arm's length so it is positioned approximately 4 inches away from the surface of the auto body panel. Start at the bottom left corner of the panel and pull back the trigger of the gun to create paint atomization through the air cap. Maintain the same distance throughout the painting process and move the arm across the panel in a single motion to the other side.
Raise the gun slightly so the next layer of application blends into the previous one by 30 percent to ensure uniform coverage between horizontal arm movements. Continue working upward in horizontal lines until the entire panel has received a full, wet coat of waterborne paint.
Remove the air line from the HVLP spray gun and plug it into an air-fed blowing unit. Position the unit approximately one meter away from the surface of the painted panel and leave in position until the waterborne color is matte in appearance. You can leave the color to air dry if blowing units are not available. If you do this, add more curing time so you achieve a full matte finish.
Apply one or more additional coats of color until full coverage is achieved, always allowing for a curing period between coats until the painted surface is matte again. On some colors with high levels of transparency, four or five coats may be required. Leave the last coat to cure fully with the aid of an air-blowing unit.
Apply a final drop coat onto the surface of the panel from a distance of 12 inches. This should be a light, full-coverage coat that allows the metallic content to sit on the surface of the panel in uniform layers. Leave the drop coat to cure before sealing in the waterborne color with a compatible clear coat.
- Photo Credit modified car image by FotoWorx from Fotolia.com
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