Proper prep.

L

Lou M.

How do you prepare a factory finish to receive epoxy as a sealer?
 
You can either wetsand with 400 to 800 or scuff with a red pad
 
Well, this is on a 1990 truck. I guess I'll see how it feathers on the couple repair areas I have.
 
If the clear is visibly faded, chalky, blistering, peeling, etc you should take it down to metal. At least in the areas that it is in that type of condition. Usually will be on the top surfaces. If the clear is in decent shape, I usually wet sand with 400 to level any orange peel, following up with 600. New stuff I usually will finish with 600 on my primed areas and 800 grit the remainder of the panel and any blend panels. Keep in mind that is when I'm doing collision repair type work.
 
1990 paint needs to be stripped, especially on the top surfaces. Your job will only be as good as what's underneath.
 
When I'm sand(ing) stripping I use 80grit on an aggressive Snap On PS100 DA sander. You could also use paint stripper although it's messy and you need to be careful on a assembled vehicle. Masking areas helps with that. If you have a slow speed air polisher you could use 8 inch 80 grit discs and follow up with the DA. Any number of choices. 80 grit would be my preferred grit for all of it.
 
We quit using paint stripper, too many downsides. For instance, if you strip with 80, you can leave traces of the factory e-coat without worries, but if you use stripper, every last molecule of finish has to come off, because it is contaminated by the stripper. Chris is on the money with the technique, we usually start with 80 grit 8" sticky discs on a soft backing pad, then finish with 80 DA. If we know that several paint jobs are on the panel, we will start with 40 to rip the top layers off, trying not to gouge the metal, then switch to 80 for the final stripping.
 
I'll never use chemical stripper again. On my first 69 Chevelle I used it to strip the whole car and at 16 years old I
learned that the negatives simply outwiegh the positives. I'm sure it has its place, but not in my garage. Maybe if I ever have to strip lead paint off something and don't want to throw lead dust all over, but that's all I can think of at the moment.
 
I pretty much only media blast or sand strip nowadays, but back when I was starting out we used a lot of it at the shop I worked at. I can remember when I was told to strip the top hood and trunklid of a mid 80's Caprice (this was early 90's I was barely 20) and so I masked it off and layed down the stripper then went to lunch.......big mistake. I remember coming back and having a real Oh S**T moment when I saw the stripper had liquefied the Lacquer paint and was running down the car everywhere. Ruined the tailights as well. Little did I know at the time what stripper does to Lacquer and that it was still being applied by GM until the late 80's on some cars. All the Old Guys I worked with back then had a good laugh at my expense.
 
Well Chris, you know what they say; 'Experience is the breeding ground of wisdom.'
 
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