I went to bare metal on a truck, shot Nason epoxy primer, worked a few areas with body filler, touched the areas with epoxy primer, next I shot some Nason Selectprime surfacer on it. During block sanding, I cut to bare metal in a few places on high spots etc. Should I spot spray a little epoxy on the bare spots or will it be ok just to spray over with more primer surfacer? Thanks

The correct answer is that you need a DTM (direct to metal) primer like epoxy on any bare metal, it doesn't matter if it's the size of a grain of sand or an entire panel.

Many guys will just go over tiny burn-through with more build primer. You will get adhesion to metal just not as good as the epoxy.

So the question is how comfortable are you with the risk, which is very low but not zero. If I was totally out of epoxy I'd probably just take the risk on a tiny burn-through. If the spot is wider than 1/4" I would not risk it.

Also, note that if you are cutting through to high spots you will need a couple more good build coats of primer, or the underlying metal work was not ready for blocking.

well if it is a "high spot" does it need tapped a little and glazed ?

Ok, I was wondering if I was just being too paranoid. I'm running a little low on epoxy, but I'll still touch up the sand thrus, and I'll shoot a couple more coats of surfacer.

Mark460 wrote:Ok, I was wondering if I was just being too paranoid. I'm running a little low on epoxy, but I'll still touch up the sand thrus, and I'll shoot a couple more coats of surfacer.

I've had the same happen to me before as well....in my case, for the small sections like yours I touched them up shooting epoxy through my airbrush (Badger Crescendo, with a 0.7 mm tip) to avoid wasting paint.

PainterDave wrote:well if it is a "high spot" does it need tapped a little and glazed ?

If you want it to look right when done you will need to make sure the panel is straight. A "high spot" is usually surrounded by some low spots and these will stick out like a sore thumb when you start applying color.
This is why the use of Guide Coat is a must if you hope to have a nice looking paint job.