Need help from paint gurus!
10-20-2002, 03:57 AM
#1
Racer
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Location: Shawnee, Kansas
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Need help from paint gurus!
My S came without the door moldings - so I bought a used set off eBay and I'm trying to paint them Guards Red PPG acrylic. They were silver. When I shoot the moldings the paint won't stick - it creates big dimples in the center and rolls off the sides, no matter how thickly I shoot it. I've tried it with and without primer - same result. Temprature has been around 60 degrees, and I'm thinning about 40/60 using one of those C02 sprayers. Any idea what I'm doing wrong?
10-20-2002, 06:24 AM
#5
Race Director
Hmmm, this is actually the toughest part of the car to paint. The side-mouldings are flexible and face an abusive life, so getting a durable paint finish requires pulling out all the stops.
As for prepping the surface, clean with DX-330 Acryli-Clean Wax & Grease remover. This stuff doesn't dissolve and soften the old paint like lacquer thinner, which can cause bleeding later. Sand entire surface with 400-grit wet&dry (best to remove ALL of the old paint so the plastic primer can stick the best, you'll appreciate it later when the new paint chips off the old layer). Then clean off again with DX-330. Wear clean gloves and wipe down the back side of the mouldings as well since stuff there can get transferred to the front as you handle the pieces.
Then apply two layers of a PPG DP-series sealer to prevent any of the previous paint from dissolving and bleeding into the new layer. Then follow with DPX-801 Plastics Primer. You may or may not wish to sand again depending upon how smoothly applied the sealer/primer.
Check the instructions on your paint. Don't know what particular PPG line you're using but the Omni, Deltron, Delta paints have a 50/50 reduction ratio. With the new low-VOC high-solids paints, you can't mix in extra reducer to make it flow into a smoother surface, the stuff just likes to stick and applying extra just causes waves & orange-peel. Make sure you use the properly-matched activator/reducer for the correct catalytic activation.
Make sure you are NOTusing a DBC/DBU base-coat paint. They are not flexible and don't give a glossy finish. You should also add some flex-additive to the final-finish top-coat paint you're using, like PPG Delta.
Also dimples (low spots?) also known as fish-eyes are typically caused by silicone contamination.
As for prepping the surface, clean with DX-330 Acryli-Clean Wax & Grease remover. This stuff doesn't dissolve and soften the old paint like lacquer thinner, which can cause bleeding later. Sand entire surface with 400-grit wet&dry (best to remove ALL of the old paint so the plastic primer can stick the best, you'll appreciate it later when the new paint chips off the old layer). Then clean off again with DX-330. Wear clean gloves and wipe down the back side of the mouldings as well since stuff there can get transferred to the front as you handle the pieces.
Then apply two layers of a PPG DP-series sealer to prevent any of the previous paint from dissolving and bleeding into the new layer. Then follow with DPX-801 Plastics Primer. You may or may not wish to sand again depending upon how smoothly applied the sealer/primer.
Check the instructions on your paint. Don't know what particular PPG line you're using but the Omni, Deltron, Delta paints have a 50/50 reduction ratio. With the new low-VOC high-solids paints, you can't mix in extra reducer to make it flow into a smoother surface, the stuff just likes to stick and applying extra just causes waves & orange-peel. Make sure you use the properly-matched activator/reducer for the correct catalytic activation.
Make sure you are NOTusing a DBC/DBU base-coat paint. They are not flexible and don't give a glossy finish. You should also add some flex-additive to the final-finish top-coat paint you're using, like PPG Delta.
Also dimples (low spots?) also known as fish-eyes are typically caused by silicone contamination.
