This seems very unusual. Fast set joint compound, in my experience, will even set (on the inside anyway) under water, as my buckets have proven.

Yet I needed a hearty amount to plug a deep hole, and it's literally been 4 days and the surface is still wet to touch, and visually you can tell it's still wet (though the dry part is slowly growing day by day).

What could be causing this? (Should I be worried about effects later on. E.G. after priming & painting)

UPDATE: It dried after 1 week, I had a dehumidifier on but didn't get a chance to put in a fan/heater yet. The day it dried it was raining a lot, ironically.


2 Answers 2


Two possibilities:

  1. There is too much humidity in your building. This can often be the case with new construction in humid areas. It can take many days for the HVAC system to remove enough humidity. In existing construction you still may have excess humidity depending on the location, such as a bathroom. You might find a dehumidifier helpful.

  2. The compound is old. In this case it may never dry. If you don't know its "vintage" scrape it off and get some new compound from a sealed container.

  • So I should clarify... I used the same compound elsewhere on the wall in a hole almost as deep, and it did dry, nonetheless I did put a dehumidifier in the room. If there aren't down the line concerns about this compound after painting & priming, then I will continue to just be patient
    – james
    Jan 1, 2021 at 21:48
  • also @jwh20 is there a point at which i should just stop waiting and remove it and redo it? i'm worried the continued moisture may damage something? nearby dried mud?
    – james
    Jan 2, 2021 at 3:54

I would redo it--you didn't choose to use hot mud to wait a week for it to dry. Second reason to redo it: the way it's supposed to dry is a chemical reaction. If that didn't happen I believe the chance of failure definitely increases, be it shrinkage, cracking, weak bond, pounding on the wall could easily compromise the bond as well.

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