> I asked here, because I thought someone might know a 'universal' sticky
> primer I can put over the skim coat layer so I can move on. [without a
> of work]
One thing you can try, and which will probably work, is to paint over
the joint compound in that area with diluted white wood glue.
Basically, you mix what wood glue into water, and use that to paint over
the joint compound in your problem area. The dry joint compound will
suck in the liquid, and the liquid will glue all the gypsum particles
together as the glue dries. There's no hard and fast rule as to how
much glue to mix with how much water. Basically, you want to solution
to be thin enough to be sucked into the joint compound by capillary
pressure. If you have too much glue, the solution will be too viscous
to do that. So, perhaps mix up a fair bit of quite dilute glue, and
apply multiple coats. That way, with each coat you introduce more glue
into the problematic joint compound, gradually making it harder and more
But, never ever paint directly over dried white wood glue because the
moisture in the new paint or primer will re-emulsify the glue causing
the joint compound to loosen up, and you'll have a mess on your hands.
So, after painting the dilute glue on and allowing it to dry overnight,
apply a skim coat of joint compound over that area (and after allowing
that skim coat to dry) THEN paint.
Or, at least that's the way I'd proceed if you don't want to scrape off
the existing joint compound and start over.