Ok so I have my car sanded down to a little reminisce of the original gm 1972(laquer?)paint and primer/bare metal. Everything's smooth a little mud work here and there but nothing thick and no rust anywhere. So I took the car to a local body shop with a pretty decent reputation and they said I HAVE to take it down to bare metal because whatever primer they where gonna shoot wasn't compatable with the original gm laquer...hmm...the painter told me he was using madallion rubber coat product. I called madallion and they said gm used urethane in 72......what's compatable what's a good product? Has anyone used madallion rubber coat stuff? Help please no garage lol bare metal here
It's Medallion Rubber Seal....that's just a brand name. They are likely talking about an epoxy primer (2 part...it's catalyzed) but without knowing exactly WHICH Rubber Seal product they are referring to this is just a guessing game. Yes, you are better off taking it to CLEAN bare metal and then sealing that off with an epoxy primer to start with. Any old paints, fillers, etc you can eliminate the less potential for problems later on after it's painted.
You do not have to sand to bare metal. Yes... there are advantages, but oxidation starts immediately when bare metal is exposed to air. Get ahold of another local body shop or a body supply store and discuss it with them. Primer/sealer should be all you need. Preferably an epoxy. I use RM Diamont paint. But there are many other good ones out there. Just depends on a body shops preference.
If you're referring to "wash" primers when you say etch primer....No....not necessary. A good epoxy primer will give great corrosion protection and is much better if the car is going to stay in primer for awhile. In fact, the traditional "etch primer" is the last thing you want to use if you are going to be applying any polyester fillers on top of this first coat. Also...your posting indicates the shop is doing the spraying....if you take it to them in bare metal I assume they will do the final DA sanding, etc that's reqiured to get to bare, fresh clean metal before spraying whatever they are going to use....at least I HOPE they are going to do that, especially given the part of the country you're in and the time of the year.
all this advice.............. first off if you wanta car lot special by all means leave the original paint on. If you want something to last make it bare metal. He was right the new paints of today are not that compatible with old laquers. The new stuff will soften up the old and then that is where the problem lies. If it softens it up and the top coat drys it seals the old soften up paints up and they never dry. That creats a place where the paint could potentially peel later. Since I have been painting and restoring cars since the mid 80s I know what Im talking about here. If its worth doing once do it correcctly so you dont have to do it twice
Ray after blasting and on the bare metal we use epoxy primer. then we use a polyester high fill primer. Then after blocking we use a regular high fill primer for the top coats to set on. We use ppg products
It's not recommended to use an etching primer over a sandblasted finish. Something about the acid in it soaks into the pores and gets trapped because the primer flashes off and the acid cannot evaporate.