I am currently remodeling a bathroom and am ready for painting after removing the old vanity and furniture. I have several questions regarding the prep work.

a) There are white thick stuffs (about 1/16") beneath the old paint (the arrows shown in the photos below). They are located over the drywall and easily sanded. What are they? Is there anyway to easily remove them without sanding which would cause a lot of dusts?

b) Should I completely scrape off the old paint before applying a primer? Or, could a primer be applied over the old paint?


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  • Do you have non-close up pictures? Also what era is the home/renovations?
    – DMoore
    Jan 25, 2016 at 15:57
  • You'll want to, as a minimum, "scuff sand" all the old paint. They usually use gloss or semigloss in bathrooms, because it shrugs off minor contaminants like toothpaste, unfortunately it also shrugs off new paint. This would manifest as peeling after a few years. Just scuff it enough to knock the gloss off. Jan 25, 2016 at 23:12

2 Answers 2


It looks like patches to the sheetrock or maybe wet spots and the rock is not in good shape. You should evaluate if the sheetrock is not solid it should be cut out and replaced. I usually use green board for repairs in bathrooms.(Green board is water resistant sheetrock). I would scrape and see if the paint is well bonded if it is well bonded fill the low spots with topping mud then prime for best results.

  • Is there water resistant sheetrock?
    – DMoore
    Jan 25, 2016 at 15:55
  • the water resistant sheetrock is called Green board it is usually green but sometimes blue. it can be used in shower stalls with tile glued over it but Cement backer board is better for tile in that case. I always use green board around showers and above the tub area at a minimum. on my own house the entire bath is green board.
    – Ed Beal
    Jan 25, 2016 at 20:05
  • Green board provides hardly any extra protection than regular gypsum. Water resistant is really pushing it - and really just creative lying.
    – DMoore
    Jan 25, 2016 at 22:34
  • What would be the best way to remove the patches?
    – DSKim
    Jan 26, 2016 at 4:41

The "thick scuffs" appear to be damage and the seam from a texture skimcoat. Your two photos show two very different things, so I'm sure what you're asking.

At any rate, you need to repair the surface by skimming with drywall joint compound, retexture as necessary, then prime the entire wall. There's no need to remove old paint unless you have a lead concern. If that's the case, be sure you understand the health risks and proper procedure for lead abatement.

  • Looks like a plaster job was done at some point. I wouldn't skim that much mud next to plaster, especially in a bathroom.
    – DMoore
    Jan 25, 2016 at 15:58

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