Tuesday, September 21, 2010

Plastic parts prep and more etch primer

Back when I sprayed the etch primer, I didn't have the forethought to realize there were a bunch of other parts of the car that were sitting over on the other side of the garage that I probably should have spray with the etch primer. Instead, I finished the car, and had about 8 oz of etch primer left, and should have used it on the parts. Instead, I just sprayed all of the spots I thought I might sand through later on. I put an extra coat on all of the raised body lines (the middle and upper lines on the sides of the car), the ridges on the hood, and every other edge I could find. While this was a good idea, better to spray the parts with the right stuff and not have to buy extra etch primer.

Since the parts that needed etch were just the metal parts, (Ie, side mirrors, gas cap, front and rear bumpers, and the rain rails) I didn't want to buy a whole other quart of etch primer. Instead I just bought a can of spray etch primer. This is single-stage paint in that it comes ready to spray. I interpret this as being sub-par to a two part (or 2k) paint that has a hardener or catalyst to cure it. We'll see over the years if this truly has a substantial difference. This 16 oz. spray can of Sherwin Williams GPB 988 Self Etching Primer cost $13.

The plastic parts don't take etch primer because the solvents and acids in the etch can eat into the plastic and ruin it, or the solvents soak into the plastic only to later screw up the paint you put on later. So, instead, the plastic parts all get a special plastic surface preparation. This is the spray can of plastic prep called: Sherwin Williams Plastic Adhesion Promoter UPO7226. It comes in a 20 oz. spray can for $17.

Here you can see Jesse, my pro painter buddy, paying the etch primer on to the metal parts. You can see how much of a pain those darn rain rails are. They won't sit on a saw horse for painting. (I came up with a great novel solution later on for the color portion of painting, so check that out before you prep or paint yours.)

Don't forget to wear gloves while you paint. They come off a lot faster than paint dried on skin does. Especially when painting these small parts that you have to hold in your hands like in this picture. A long sleeve shirt will also go a long way to keep paint of arms and arm hair. Especially for the plastic adhesion promoter which is clear, and sticky as all get out.

Here you can see that I've got the plastic parts up on saw horses since most of the sides have to be painted. You can also see all the spots I snaded through on down to the black plastic. When spraying this plastic adhesion promoter, lay it on really thin and do a few coats. I got a little over eager laying down a thick coat and it dripped all over the place and I got quite a few big runs and sags. Espcially near the indents where I had to spray a lot to get all of the surfaces.

Total time painting today: 2 hours
Total cost of materials: $30 ($13 for etch primer, $17 for plastic adhesion promoter)

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