I need to get a sample of some drywall joint compound for asbestos testing in a house I'm renovating. I pulled away some of the base boards in the corner and found something that I believe to be joint compound, but I need someone to verify before I take a sample and send it in.

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I'm looking at the tan colored substance by the nail in the corner (I highlighted it in the picture). Is this drywall joint compound?

FYI, we have already had some lab tests done and found asbestos (chrysotile) in the popcorn ceiling in one room and the linoleum flooring in the kitchen (currently covered up by laminate). The abatement company recommended checking the joint compound in the wall.


This substance was indeed drywall joint compound and it did contain asbestos, which is a bummer. Now on to abatement...

  • Are you trying really hard to not damage the drywall above the baseboard line? If that's not a concern, put a putty knife between the paper and the mud in that L shaped divot on the right. Push toward the corner and you should get mud, texture and paper tape. Commented May 16, 2021 at 16:51
  • No it's fine to damage this area since this wall is going away. So the stuff with the L shaped divot is joint compound?
    – d512
    Commented May 16, 2021 at 18:42
  • 1
    Asbestos wouldn't be added to joint compound, mastic, or adhesives. Those things aren't fuel sources, so there's no need to fireproof them.
    – dandavis
    Commented May 16, 2021 at 21:33
  • The stuff around the L shaped divot is probably a combination of texture and joint compound. If you dig to the corner, you'll probably get both. (In a perfect world, the paper corner would be in there as well, as that would indicate that the stuff under it and the first layer over it is joint compound.) Commented May 17, 2021 at 0:28
  • 1
    That would have been good info to have included in the question initially. If you look at the asbestos tagged questions, you'll see that there's lots of (likely) needless paranoia. Providing the context that you've got a very credible reason to be concerned will avoid lots of wondering from those looking at your question.
    – FreeMan
    Commented May 17, 2021 at 17:56

2 Answers 2


I believe what I see is the paper for the drywall. There are adhesives but I see wrinkled paper if there is a filler in that point not the paper a clear photo of the tan material would be needed to make a guess. Over the years I have seen everything from sheetrock mud to modeling clay used to patch drywall with even mortar in a few cases. Note sheetrock or drywall mud can discolor yo a brown or iron oxide color when metal corners are used and if there is moisture in the room other than the torn paper to the left of the nail I don’t see tan.

  • Sorry, I realize that I wasn't being clear about what I was referring to in the pic. I put a border around the material I'm thinking is the joint compound.
    – d512
    Commented May 16, 2021 at 18:48
  • That’s just mud that was put on thick.
    – Ed Beal
    Commented May 16, 2021 at 23:23
  • Sorry, I guess I'm confused, isn't "mud" the same thing as drywall joint compound?
    – d512
    Commented May 17, 2021 at 2:11
  • There are many different types topping, hot, and standard most pros refer to them all all as mud.
    – Ed Beal
    Commented May 17, 2021 at 13:15

Yes in the loosest sense of the term. Yes it was something that was used just like joint compound. So it is either joint compound or a relative.

You can tell that it was gradually increased towards the corner, probably to get things closer to a 90 degree angle and just feathered out from the corner.

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