It's been so long since I've held a paint gun... I need some refreshing.

I know that ideally, wash-primer and primer-surfacer should be from the same paint system. Is that a hard and fast rule?

I want to lay down a PPG wash-primer (1791 primer/1792 catylist) on bare metal and later coat it with an (unknown yet) brand of primer surfacer. My (often faulty) memory seems to tell me that wash-primer is pretty generic.

Is there a signficant chance of bubbling or other incompatibility?

-Rusty

Rusty

You'll want to topcoat that with either epoxy primer or a 2k urethane primer/surfacer for sanding. You should be OK with any 2k primer surfacer but it might be wise to use K36 or other compatible PPG product. Your other option is to use epoxy on the bare metal if the old paint was recently stripped off and degreased. You can let the epoxy flash and immediately shoot K36 or other 2k primer on top of that.
The wash primer is incompatible over acrylic lacquer and spot putty so make sure all of those are removed if they exist.

With the rule changes and reformulations of paints...it depends on the area you live in...."I" would go talk to the paint supplier and ask them. Some primers and fillers are not available in metropolitian areas due to environmenatl regulations that have been forced on us by the State rule makers.

Ask the guy that is trianed at the factory for the "system" that is available in your area. Paints need to have the right undercoats to work right...

Some newer paints can't be applied by the old B-18 Binks cup gun...you need an HVLP.

Edumecate me.

I understand the epoxy primers, primer sufacers but what is a wash primer and it's use?

Essentially a self-etch primer. Has an acid base that adheres to bare metal and provide a grip for other primers and topcoats.

For bare metal I use DuPont Vari-Prime, but it's expensive.

If you don't want to sand it later, you can use the DuPont non sanding primer, and then paint it right away. This works good for engine compartments, inside the trunks, etc, where you don't want to have to go back and sand all of that for proper adhesion. You do need a good block of uninterupted time though. To prime twice, and paint it'll take you at least six hours, by the time you mix your paints, clean your gun, etc.

If it's going to be sanded and blocked, I use the Vari-Prime and than paint it with the DuPont URO high build primer.

I use the DuPont line because that's what's available locally.

I would recommend using the entire system you can get locally. That is, use all PPG, DuPont, Lesonal, Sikkens, whatever, just stick with the same brand from bare metal up. You'll have less potential for problems that way.

ive used alot of expensive primers, mostly dupont, but bang for the buck , evercoat makes a killer eurethane filler primer that does great. I use the hell out of that stuff. Sands better than the 2k and self etch primer i always used dupont