"Paul Soderman" wrote in message
oups.com...
I put in 3/8th sheetrock over an old cracked ceiling; finished my
taping and spackling and put on 2 coats of primer (it was the glossy
kind, all that we had) and then put on one coat of ceiling paint (flat
white) before realizing that I should have done one of the seams a
little bit better. I guess I felt rushed, but anyway, I'm hoping to
rectify my error by trying to even out this seam, which is simply a
bit depressed than the surrounding boards, by using a 6 inch spackle
knife to apply another thin coat or two to do a better job.

Is there any specific way to approach this? I would think that once
the paint is on, there is something that needs to be done, but I'm not
sure. Hopefully, maybe just a little abrasion to roughen up the
painted surface so as to have the mud adhere? I wasn't planning to put
up additional tape for this last couple of passes with the larger
knife and some spackle.

Most do-it-yourself types make the mistake of thinking that the first coat
of spackling must be done wonderfully. It does not because you have the
advantage of turning this into a longer project (which the pros cannot).
They cannot be screwing around in your home for three days, but you can.

Lay that spackling compound on with your blade, only caring about coverage
and smoothness at the seam. Don't worry about the edges of your repair at
this point in time. Let that dry and then go back and spackle the edges of
your patch. Let that dry and inspect and apply a third coat where there are
ridges and lines. Then, sand it a bit and prime it and paint it and you
will be amazed at the beauty of your work. Sanding makes a mess, so I'd
advise a drop-cloth.

Pre-sanding might be necessary with a gloss finish, but I doubt that.