So if I'm sanding, scuffing, blocking, prepping, etc. etc. ,but it may be weeks, or even months before paint, what do I do if I need to go down to bare metal? 99% of the little tweaks should NOT need that, but there are one or two that I'd feel better taking down to metal.

do I need to prep it (and with what?) right then and there, -or will a light scuff at the time of paint do it?

It's ironic really. 95% of the car is perfect, and doesn't need paint, but the small little things here and there are starting to add up.

 

I stripped my entire car down to bare metal. I used Eastwood 2 part epoxy primer. I still haven't painted it yet and it's holding up good so far. There's pics and more details in my build thread (link in signature)

 

The body shop used SEM gray self etch primer for the small bare spots during prep period, in advance of leveling primer.

But two-part epoxy primer is something I've heard of, too, as being excellent. I used two-part epoxy primer in spray cans when I did past local spot work. But may cost a lot more for large areas over time because cans are good for only short period after mixing.

I offer what I think I saw at the shop. Hopefully I am repeating it correctly here.

 

Appreciate the responses guys...thanks.

 

You can use Self-etching primer or an epoxy primer. Self-etching has lost popularity because Epoxy primers have gotten that good. Carefully read the prep instructions for your product. Some primers specifically state you shall not use any kind of metal etch or metal prep before spraying the product. If you use one of those try to stay with the same brand that the paint will be. A few things to note:
1. Epoxy primer is very thin and is only meant as a sealer.
2. You will have to sand it down when you are wanting to spray primer in a few months and you will most likely be topcoating it with a primer/surfacer that needs 120-220 grit scratches.
3. Since the epoxy is so thin, if you are only applying a single coat for rust prevention you may end up sanding much of it off and respraying another coat of epoxy. So just remember that this is only being done to stave of rust setting up home. This will not be the first step in your body prep and when you come back you can hop back in and spray 2K primer.

Since most of it will be sanded off in preparation for a respray in the spring I would just look into Eastwood or SEM epoxy or self-etching primer in a can. Save money and time since again, much of the product may be sanded off.