Sand/Fill Primer

What I do lay down some cheap lacquer guide coat on the areas in question. Block them out to get rid of high/low spots. Use as long of a block as you can and you'll get it straight.

The best thing to do is lay down the epoxy over bare metal. This works great for fighting against corrosion and is great for adhesion. You dont have to wet sand this step. Nextwhen you say "primer" I assume you're referring to primer surfacer. Well. Shoot the surfacer. Block this down. Guide coat (we use a can of spray paint. Sand away until shes straight. Shoot more if you want, just make sure that you get that body straight. After it's straight. Go ahead and shoot some sealer. I sometimes use the epoxy just reduce it 10% so it flows better. Its important to shoot this coat 1/2 wet with a 50% overlap. No sanding needed here. You can wet sand this coat but dont go too deep. If you do wet sand this will just provide for a smoother finish. If youre satisfied. Go and shoot the BC/CC. Hope I can help.

Gbodyera, has it right on the money. Use the epoxy first for adhesion and corrosion and then apply the primer/filler over the top of the epoxy. You can do your body work right over the top of the epoxy. The filler will adhere better to that than bare metal. Make sure you use a good catalyzed primer. Its a little more expensive but does a better job.

1st of all. Is the paint that was on there before you stripped it down the original? What kind of primer do you have on there with the filler?

Ok. After you have all of your filler spots sanded. Shoot the whole car with epoxy. Next shoot some 2k High Build Primer Surfacer. If youre not familiar with it, this stuff is thick. The surfacer will give you you build.After you shoot a coat or 2 of this go ahead and block sand and get your body straight now. (this is the part we discussed about guide coating and such). After your body is straight as you want it. Then you may want to shoot a sealer. (Epoxy/ 10% reducer). Shooting sealer at this point will do just as it says "seal" the Base Coat from the surfacer. If youre shooting a black base or another dark color, I hope your body is straight. Darker colors are very unforgiving in bodywork. I hope I helped you. Also I'd love to see some progress pics.

I forgot to mention. Putting filler over welded spots isnt the best way to go. As is doesnt offer all of the protection epoxy does.