What is the minimum amount of dust that can be left on a wall before it adversely affects primer application? If it has to be completely free of dust, how do you get it all? Taking a damp rag over the wall seems to be the way to do this based on my own research, but then you have to rinse it wring it out. This dirties up the water which just means more particulates would end up back on the wall as dust after the water evaporates. Plus, going over all walls and ceiling of a 250 sq ft room with a damp rag just seems like a PIA. Is there a better way?

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    AFAIK, most drywall 'dust' is heavy enough that it just falls to the floor. Anything left on the wall doesn't seem to have any ill effects on the primer.
    – DA01
    Commented Dec 10, 2012 at 4:53
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    What you did is exactly right. The drywall needs to be as dust free as possible or your finish will have lots of bumps in it, enclosed with primer. Sometimes you just gotta change the rinse water in your bucket. Good job. Commented Dec 10, 2012 at 11:24
  • I'll note that I didn't even use a bucket of water. I just used running water straight from the sink to ensure no compound made its way back to any surfaces. I probably used more water that way, but it was guaranteed to be clean and the result was a wall with hardly any dust remaining. I had to pat myself on the back for a job well done! Commented Dec 10, 2012 at 15:19

5 Answers 5


You didnt have to use a mop, for next time all you have to do is take a broom to it and sweep the dust off, put some primer on, wait for it to dry and then take a pole sander to it, and dust clumps left on the wall is forever gone.

  • This is a good solution. I think the mop was overkill, but I doubt there will be any adverse reactions. Commented Mar 20, 2015 at 14:58

I picked up a mop with a wringable, rectangular sponge head from the drug store. What I did was get it wet and wring it out to dampness. After taking it from the ceiling to the floor and stepping to the side a bit to repeat, I'd be able to get about three sweeps of the wall before the head looked like it needed to be wrung out again. I did all walls and ceiling of my 250 SF room in well under an hour.

There is now only ever so slight of a trace of dust on the surfaces. It may be ready to prime right now, but, since it was so easy, I'll probably do it once more tomorrow for good measure. It will go even quicker this time since there will be far less wringing out of the sponge head.

  • The 2 bucket method for minimizing water usage: Dip only from 'clean' bucket. Rinse and wring only to 'dirty' (starts empty) bucket.
    – HerrBag
    Commented Apr 12, 2013 at 15:46
  • I wrung directly into the tub. Commented Apr 12, 2013 at 18:01

I've heard from professional drywallers/painters that they don't even try and take all the dust from sanding off, just a quick sweep of the walls to get the majority off. The really fine drywall dust will add itself to the primer coat and help smooth it out. I tried this approach when I remodeled my living room and the results were great.


I recently prepped two rooms for primer and paint. I read that the best prep is to use water and sponge as you did. It was not so much the drywall compound dust, as the thin coating of kaolin the drywall manufacturer uses to keep sheets from sticking together that the water will take off.

I currently have a garage ceiling to scrape, mud, and prime, that pro painters apparently didn't prime. The paint is peeling off every where there is a joint, and will peel off the surface with a quick swipe of a 5-in-1 tool. Bozos!


Using a Dyson, vacuum the wall.

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    Hello, and welcome to Stack Exchange. This isn't really a useful answer, as a Dyson will do just as good a job as any vacuum cleaner (it may emit less dust, but the wall doesn't care). Commented Apr 15, 2016 at 21:46

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