I have a wall that needs a new paint job. I'm trying to make a call on how much prep work is needed before applying the paint. From the other questions it's not what would be the properties or a well prepared surface so am providing a real example.

The below table gives a comparison between the current state and a sanded state.

Original Sanded
enter image description here Two

This was sanded manually with a 120grit paper roughly 15 seconds The 'roughness' is less than 1mm deep in both cases.

I'm trying to understand to what prep work is needed to reduce the risk that the new paint will peel or visible uneven. Am not looking for perfection form that close up just want to that it looks like an homogeneously painted wall when looking at it from half a meter or on a sunny day.

Some options that come to mind:

  • sanding the old with an electrical sander all the way to the plaster
  • applying drywall mud to fill the little gaps
  • just sanding lightly with a finer sandpaper and applying a primer

What would classify the wall as paint ready and if it isn't, which steps preparation steps to choose?

  • 90% of a good paint job is the preparation work, if that helps you wrap your mind around the distribution of effort. Many folks short the prep, and then get to do the whole job over, wasting the cost of the paint they applied the first time, and whatever labor went into the first time.
    – Ecnerwal
    Commented Dec 6, 2023 at 19:00
  • Paint will not hide imperfections of surface. If covering with mud, it would be best to feather out the mud to at least the edges of the second picture if not more. If your fingers can feel imperfection, you will see it after painting. After the wall is smooth, the a good cleaning/washing/dusting.
    – crip659
    Commented Dec 6, 2023 at 19:09
  • @crip659 Thanks, this is a block wall, not drywall. In Europe it's common to do something like 'full wall smoothing' for things like these. But I can't fine an English term that reflects this. It's not the same mudding as one uses to cover the drywall joint neither is it a filler for bigger holes. Commented Dec 6, 2023 at 19:13

1 Answer 1


Sanding is not an appropriate technique for painted walls. You never* want to sand latex paint with the intent of grinding it off. That's not likely to go well as it leaves behind shredded paint and an uneven surface where the paint peels or melts.

You need to skim the wall with a topping compound using a wide knife (12" or wider), then sand lightly with a large pad or drywall screen to eliminate very minor imperfections. Do the whole wall, scraping gently with the knife between applications to remove crumbs and thin edges. Use a strong light at a low angle to examine, then repeat. You're done when you see no shadows.

Now prime the surface, and check it again with the light. Make additional skim repairs if needed and re-prime.

Now you're ready for paint.

* Never say never. If you have, say, a pointy dab-and-pull type of texture it may make sense to grind off the peaks before you begin skimming. If you have something robust like plaster underneath softer texture you could feasibly grind that off with low-grit sandpaper, again before you start skimming. There's always skimming, though, even if you intend to retexture.

  • Why do you skim prime and then check, instead of concluding the skimming before going for priming? Or rephrased - what is the role of priming and why not apply paint to a finely skimmed wall? Commented Dec 6, 2023 at 20:35
  • You do. But you're new at this and may have missed a spot. If you want a good outcome, check again.
    – isherwood
    Commented Dec 6, 2023 at 20:58
  • @TheMeaningfulEngineer are you looking for a smooth finish, or looking to match existing orange peel texture?
    – Huesmann
    Commented Dec 7, 2023 at 15:35
  • @Huesmann I think my images are too close up and are giving an impression of a texture which doesn't exist. It's not a deliberate texture just bumps from paint, you can't see it unless you close up. I wasn't originally planning to skim the whole thing but sanding the paint created little holes (sanded example) and that didn't look like a good base for the next layer of paint. Eventually I skimmed everything with mud and sanded it. The base looks good now, but it was a lot so will try another room without it just to see if it's worth it. Commented Dec 10, 2023 at 20:59
  • I know. Orange peel is a common result of many layers of paint, or certain painting techniques—not necessarily an intentional texture.
    – Huesmann
    Commented Dec 11, 2023 at 13:08

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