Preventing Contamination

Preventing Contamination

Overview – Dirt is Your Enemy

Especially with today’s clear urethane coat finishes and super-smooth, thin-coat finishes. And with the public’s increased desire to have vehicles refinished to the same exacting standards as the original finish.

Clear coats and smooth coats bring dirt and imperfections to light that otherwise couldn’t be seen. But under clear coats or within super-smooth coats, particles as small as 14 microns — smaller than the thickness of a human hair — stand out. Fibrous particles are especially visible.

That’s why today’s downdraft spray paint booths have become essential today.

No one would drive an obviously dirty vehicle into a paint booth and expect a clean paint job. Yet even clean-looking vehicles can be a source of contamination. Take the time to do good prep work — an extra hour spent in preparation will save many hours of corrections later. Here we present steps you can take to avoid driving dirt into the paint booth.

Clean – Rid the Surface of Dirt and Contaminants
*Outside the booth for steps 1-8

1. Pressure Wash

  1. Soap and water
  2. 1000 psi
  3. All surfaces, between door jambs and seams, including the undercarriage

2. Degrease / Chemical Wash the Car

  1. Work in a well-ventilated area like a prep work station.
  2. Use high-quality wipes developed for this purpose which are lint-free even when moist.
  3. Use white wipes to show the dirt. Do not use cloth shop towels to wipe down a vehicle, they are loaded with fibers.
  4. Use one towel for solvent wipe and a separate one for drying.
  5. When using a prep cleaner, do small areas at a time and keep turning the cloth over.
  6. Use plenty of cleaning solvent.
  7. If painting door jambs is planned, remember to degrease the door jambs carefully, remove all stickers on the jambs and vacuum the interior.

3. Sand and Prime

  1. Be careful not to touch vehicle with uncovered hands during this stage.

4. High Pressure Blow-Off

  1. Outside of the booth
  2. 125 psi minimum
  3. Between panel joints, door jambs, seams and cowl where dirt likes to accumulate

5. Mask, using the proper masking paper for the task — priming or base/clear coat.

  1. Don’t skimp on masking paper or tape quality. Lower quality papers contain loose fibers and can soften and hold lint when wiped with solvent, which is then released during painting.
  2. Use only top-of-the-line, first-quality materials such as 3M. This company makes two tightly bonded papers that eliminate paper fibers. One fiber in paint will cost you more than any savings you might get with inferior materials.
  3. Don’t use low quality masking paper around urethane paints or next to an area to be sprayed. Urethanes cause green paper fibers to “fuzz-up” — introducing fibers into the environment.
  4. Eliminate as many wrinkles as possible when masking. These catch dirt and overspray.

6. Degrease Again

  1. This removes any grease from hands deposited on the vehicle during previous steps.
  2. Use only high-quality wipes developed for this purpose which are lint-free even when moist. Do not use cloth shop towels, which are loaded with fibers, to wipe down a vehicle. White wipes show dirt better.
  3. Use one towel for solvent wipe and a separate one for drying.
  4. Do small areas at a time, keep turning the cloth over, and use plenty of cleaning solvent.
  5. Keep turning the tack cloth over and refolding it to expose as much new surface area as possible while tacking large areas.

7. Blow with full pressure and tak

  1. Blow off 100% of vehicle with high pressure.
  2. Tack repair area and all masking paper

8. Move the vehicle to the booth.

  1. With spray booth operating in the paint mode, load vehicle, centered over grates front-to-back and side-to-side.
  2. Close all doors to the booth

9. Final tack inside the booth.

  1. Bag areas not being painted, tuck plastic under paper and tape all edges.
  2. Paper or plastic cover should not extend more than 6 inches below the vehicle.
  3. Never cover any wheel well 100%.
  4. Use paper or plastic wheel covers that can be thrown away after every use.
  5. Blow off vehicle and masking paper with 40 psi. Tack one or two times, including the masking paper and tape.
  6. Attach a ground strap to the vehicle and disconnect the battery to minimize electric charges and static electricity. These can draw dust and dirt to the vehicle’s surface.
  7. Apply an anti-static solution to reduce static electricity.
  8. The final tack should be made without blowing. Air blasts can blow dirt to another area which could miss the tack cloth.