Pre-Painting Plaster Patching

[Gomez]

I am about to paint my living room. The house is about 45 years old and has plaster walls. The room had wallpaper on it when we moved in eight years ago. We removed the wallpaper and painted. After a couple of years, we noticed the original primer (what we painted over) had started to peel in a few areas. Now I'm scraping all the paint off down to the plaster wherever I can, but some areas the paint is bonded to the plaster. My thought is to feather in with some kind of spackle.

So my question is, what is the best type of spackle to use here? I read that Plaster of Paris would need to be mixed with lime for this.

Do I have to do anything to the plaster to make the paint stick better? I thought moisture was somehow getting behind the wall causing paint to peel, but the plaster is still pure white.

Thanks!

 

[MikePA]

I've only used Plaster of Paris for large holes, it's not real good for shallow/small holes. The advantage to using it is that it doesn't shrink like spackling compound. BTW, I've never mixed it with lime. I just mixed it with water in a bowl. Don't mix more than you can use in 10 or 15 minutes and clean up the tools right away. If you have a lot left over, do not dump it down the drain. I know someone who did that only to have it harden in the P trap. When I've used it on large holes, e.g., the lathe is showing, I've moistened the lath first so the plaster doesn't dry too fast. I also do not make the mistake of overfilling the hole thinking I will just sand it. Plaster of Paris is harder than spackling compound.

For everything else, DAP spackling compound works fine or if you don't have that, joint compound can be used too. Paint peeling is usually caused by either poor surface preparation (no offense intended) or moisture working it's way out of the plaster. Did you steam the wallpaper off?

Our house is over 100 years old and has horse hair plaster. I've repaired more holes and cracks than I care to remember.

 

[gsxr1100]

I agree with MikePA but I use Plaster of Paris on all holes. The trick for me is to mix it like concrete. Then go nuts with it for about 10 minutes since it dries fast. It is like $2.99 for 2 lbs at the depot.

I do almost the same as Mike, I wet the tools AND the area to be applied to.

It dries in like 3 hours & you can sand etc. The BAD part is you better be good using your tools since when it dries, again like a rock. So any high spots take forever to remove when screening.

Joint compound sucks I think but is easy to screen or sand down. The best part of Plaster of Paris is no shrinking down the road like compound.

I love plaster since it makes the house very quiet but this is my last older house (1959) with true 2x4. Next house is all new, no messing around. I like messing with this and that, but I can at least say I did the complete house myself..

See, my life is not all oil! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

 

[inveresk]

The secret to good adhesion of paint to plaster is to use a thinned first coat of paint. If you apply it unthinned, it can peel off in sheets when you roller on coat 2. Thinning, about 50/50, really improves the adhesion.

When repairing plaster, drywall fastset works fine and sands well to a feather edge.

On new plaster, it helps to "size' the walls before painting. A thinned application of water based, pva adhesive does the job. You might be wise to do this where you repair the plaster.

If after all this work the walls are still not great, you can apply a lining paper before you paint. This will disguise most of the defects if you use a reasonable weight of paper, 100 grammes or better.