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Paint peeled in a few areas I'm assuming from bad prep many years back, and no primer. Should I go ahead and sand/prime these areas before mudding and repairing? The exposed plaster is super slick and very smooth. Sorry if this is a subjective question, I'm simply trying to understand IF primer is recommended before repair, or just go straight to mud coat (Easy Sand Joint Setting Compound, or Plus 3 Pre-Mixed Compound) and then prime after.

This surface is going to be painted with a standard 3/8" nap roller after to give it a slight roller texture, so it won't be left as smooth as the plaster is, and instead will have roller texture.

Thanksenter image description here

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    Well, if the surface is very smooth, you can't expect anything to stick to it, it's like trying to mud or paint a piece of glass. It needs to be roughed up simply so the next layer can engage.
    – Harper - Reinstate Monica
    Commented Sep 14, 2022 at 20:28
  • @Harper-ReinstateMonica Great point. So would I sand it to rough it up, then mud it? Or sand and prime, then mud in this case?
    – RocketManZ
    Commented Sep 14, 2022 at 20:30
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    Well the mud doesn't need primer to attach to the old surface. You only really need primer under paint. I don't like putting primer under anything but paint unless they are similar chemistries.
    – Harper - Reinstate Monica
    Commented Sep 14, 2022 at 20:33
  • gotta agree with @Harper-ReinstateMonica it needs to be roughed up. Get Vinny and Guido to "rough it up"! Sorry, couldn't resist. Anyway, some 60 grit or 80 grit on a 1/4 sheet sander should get the job done in no time. I've found that mud sticks to about anything, but roughing it up just a bit will give it some teeth to hang onto. Fix first, plaster, prime and paint later.
    – George Anderson
    Commented Sep 14, 2022 at 20:51
  • @GeorgeAnderson Thanks for the extra info on grit and all. I'm going to give this a go. I used Easy Sand joint setting hot mud in my own home years back on all my plaster repairs and it bonded fine, but I don't recall finding anything this glass smooth. Would you use easy sand joint compound/hot mud for your first coat in this case to get a good bond? I think I'm going to do hot mud for the 1st fill in coat, then I'll use Plus 3 or an all purpose type of premixed mud for the final fill and feathering stages.
    – RocketManZ
    Commented Sep 14, 2022 at 20:58

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Paint peeled in a few areas

indication you will have to sand the surface.

Using Drywall specific grit paper, and covering large area then already visible peeling, since there might be already many micro cracks in the paint.

Regular sanding paper will clog up rather quickly.

Drywall specific paper looks like this, and lasts longer and works better.

sanding

Then prime over it.

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  • My only question is why the guy took a picture of drywall sandpaper while barefoot and wearing pajamas. Who does that???
    – FreeMan
    Commented Sep 15, 2022 at 12:10

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