So I put down 3 coats of DP50 and then did the usual filler work and then covered it with another 3 coats of NCP280. In going thru the initial blocking, I find there's a spot I missed where a small wave in the body will require a little massaging and some additional filler.

Concerned that if I put filler over the NCP280, it'll either cause lifting or have adhesion problems. Should we sand thru the NCP and get back into the DP and start the layering process over again or is a week-long cured NCP okay to put filler over provided DP 50 is spotted over it again?

(In typing this, I suspect I may just sand thru and start over again in this 4" x 6" section!)

Just give a 80 grit scratch then apply filler. Any good filler is made for that. You could for example put filler over a painted surface, but clean and give it a swipe with sandpaper first.

Depending on how big your dent is, yes you can or no you can NOT.
If all you have is small minor imperfection like a wave or dimple YES you can apply a little filler over that NCP.

But if you have a nice dent NO you can NOT apply over NCP.
ALso regular filler should not be used like this, get yourself some poly filler. Poly filler is made for this purpose.
A few examples would be Evercoat's metal glaze, Upol's Dolphin glaze and USC's icing...Eric

Actually - not even a dent, just a few little (LITTLE) dimples where trim holes were welded and I thought they were leveled.

Probably will try putting a little dab of the 3M red body putty on it and smooth it to paper thin. I know some don't like it, because it shrinks a tad, but after it's cured and another coat or two, it's been fine for me and I love the smooth workability of it over instead of regular filler. I think it'll go on over the primer with no problems too.

That red putty will come back to haunt to you.

You can buy a tube of Upol's Dolphin glaze for like 12 bucks, probably the same cost as the 3M stuff.
Check out www.toolsusa.com (http://www.toolsusa.com) they sell Upol stuff online.
Personally I prefer the Upol brand over any other poly glaze.

The problem with that putty is that is NEVER cures it dries, doesnt cure.
If you re-introduce solvents to that putty you can liquidify it, make it soft again anyways.

How much Time and Money do you have invested in this car right now? Why cheap out over a 12 dollar tube of glaze?

Junk that red putty IMO! Use a polyester glaze as Eric previously mentioned, it spreads as good as the laquer based stuff you've used in the past-BUT DOESN'T SHRINK OR SWELL OR CRACK OR PEEL.

Not so much a case of "cheaping out" as habit.
I never had problems with it previously, but that certainly doesn't mean it won't start at some point.

Next supply trip, I'll jump over to the glaze instead. Not familiar with it, but I'm sure it's as easy to use.

Interesting though about the softening issue of the putty when the solvents hit it. I wound up after sanding with a paper-thin layer that was indeed dry.
(I understand the diff of drying and curing however!)
I have DP50 over it now without any issues and will end up like the rest of the pieces with NCP on top of that as a sanding layer. Once cured, do I still face the same problem, or will 3 coats of NCP suffice as a sealant once the NCP cures? The putty is transparent-thin and is sitting atop Rage filler which sits atop DP50 and then once sanded, it will have 3 coats of NCP over it all. I always let the NCP cure at least a day or two before sanding. (it's a minimum of 60 degrees when I spray a panel in the garage here)

REALLY don't want to go back and strip the whole dang thing again! I'm hoping that because the 3M putty is so extremely thin, it won't be an issue once covered, but I'll definitely make the change to glaze when smoothing the 1/4 weld lines later!

Thoughts?