My latest project is to paint some of these Subaru body kit parts that one of the guys picked up from Craigslist. Since I really want to get better, I figure this will make some good practice. In total, I have 2 rear valences and one rear wing that needs to be painted silver.
The first step was to sand off all that old weak paint. From what I understand, you can get away without sanding if the current layer of paint is strong enough. All you have to do is scuff it up and possibly use an adhesion promoter on top, followed by the base and clear coats.
But since the paint on these valences was flaking off, I figured it best to remove all the paint and start fresh with a new coat of primer.
Here’s how the valences look after sanding and cleaning. It’s important to remove any traces of oil (even from finger prints) before spraying the very first coat of primer, or else it might not stick as well as it could. These are the steps I took up to the point of the picture above:
1. Put on latex gloves.
2. Sand off old paint.
3. Wash parts using dish washing detergent and water.
4. Dry with a cloth.
5. Final wipe-down using acetone and another clean cloth.
6. Remove remaining debris/dust/etc using a tack cloth.
Then, it was time to spray a few coats of primer onto the parts. I did about 3 coats on each part. Normally, you might only do 1 or 2 good coats, but I did a bit more because I’m planning on doing a bit of sanding before I spray the base color coat. In the next picture, you’ll see why.
So, as you can see, there’s a bit of a texture on the primer. It’s not the primer itself, actually, it’s fuzzy because of the sanding job I did on step 1. Because of the grit of the sand paper, sanding off the old paint left a bit of a gritty texture on the plastic surface. I didn’t want to smooth out the bare material itself because I didn’t want it to become too thin from sanding.
Instead, the plan was to spray on a few coats of primer, let it dry, then do some sanding using 600 grit by hand. That should be good enough to make the surface nice and even and ready for the base coat, without affecting the raw plastic too much. If too much primer comes off while sanding, then I can always add a final coat of primer before spraying the base.