sanding after painting


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Old 02-11-11, 04:56 AM
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sanding after painting

I filled some holes in my sons wall and thought they were sanded well enough, but they weren't. After painting, you can see where they are. I sanded one after I painted, but the paint started to peel? Is there something I can do now? Do I have to wait until the paint cures? Thanks for your help.
 
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Old 02-11-11, 05:05 AM
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Welcome to the forums!

Latex paint doesn't sand well
IMO you'd be better off coating over the the bad spots with some joint compound or spackling and then sanding it when dry. Feathering out the repair will be a lot easier. If it's a really bad spot you could scrape it down and then repatch but generally adding a little j/c is the best fix. Don't forget to sand and prime before you touch it up with paint.
 
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Old 02-11-11, 07:49 AM
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Thank you. There are too many spots that are showing through. I might just have to leave them. I appreciate you taking the time to answer me.
 
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Old 02-11-11, 09:04 AM
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I learned this the hard way as well - paint makes imperfections in your wall more noticable, not less so
 
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Old 02-11-11, 12:51 PM
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Once the curtains are hung, pics on the wall and furniture placed - those spots might not be as apparent and as time goes on we tend to get used to little imperfections and no longer notice them. Of course if a painter like me comes to visit, he'll probably notice but then my wife tells me I shouldn't be looking at the paint job and carpenter work - after all, we just came to visit
 
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Old 02-11-11, 02:07 PM
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Haha that's funny. I do have a painter friend and I know he would be appalled.lol You are right, I'm just going to tell my son to put a lot of posters up.
 
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Old 02-12-11, 10:50 PM
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Gailcar:

From what I can tell, you simply sanded down joint compound and applied paint to it without using a primer first.


What you are seeing is the difference in gloss (as opposed to difference in colour) in those areas where you painted over dry joint compound. That's because a PRIMER (latex or oil based) will contain plenty of large extender pigments which would plug up the surface porosity of drywall joint compound so that any top coat wouldn't be absorbed into the joint compound.

Since I'm not hearing you say that you used a primer, then I suspect what you did was apply paint over drywall joint compound without using a primer first. And, because the paint would have been absorbed into the porosity of the joint compound, what you're seeing are flat areas where the paint has been absorbed into the joint compound.

I would simply prime over those spots with a latex or oil based primer, and THEN paint over the primer (when dry). The large extender pigments in the primer will plug up the holes in the joint compound which are currently absorbing paint. That will prevent the joint compound from absorbing paint, and result in a uniform gloss in your paint job.
 
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Old 02-16-11, 04:44 AM
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Thank you very much for that explanation. I didn't use primer and was wondering what it actually does. I will defintely use it the next time I paint. I didn't really think it was necessary and now I know it is. Unfortunately, for the room I just painted, I also didnt' sand down those spots enough. I'm just telling my son to put up posters, but I have good information for when I paint my bathroom
 
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Old 02-16-11, 10:27 AM
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If it was only that you hadn't used primer over the repairs, a second coat of paint will usually suffice. In this case, more sanding would be needed, at which point priming and painting would be called for.
 
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Old 02-16-11, 09:50 PM
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I thought the same thing once. I figured why prime and clean the roller and then paint when I can just paint twice and leave the roller wrapped in a plastic bag between coats.

I was surprised to find that it took about 4 coats of satin before the gloss level of the repair matched that of the surrounding wall. I was also expecting that another coat of paint woulda solved the problem, but that won't be the first time that what we expect is completely different than what we discover.
 
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Old 02-17-11, 06:29 AM
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It depends on the paint, usually one additional coat is enough, obviously not always
 
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Old 02-17-11, 02:59 PM
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Flat paints are generally more forgiving than enamels...... and then there are the quality differences between different lines/brands of paint. Priming a raw substrate is always best but some times you can cheat and get away with it
 
 

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