Old drywall compound mud re-use.


Old 06-13-15, 02:31 PM
Thread Starter
Join Date: Jun 2015
Location: USA
Posts: 1
Old drywall compound mud re-use.

I've seen various precautions about using previously used drywall mud. I have about 40 pounds of old premix from 2005 and 2014. Any advice regarding longer terms complications beyond my 1 week experimental results below?

Experiment: Use of leftover 10 year old drywall compound mud.

User: Homeowner, minimal experience, 2 days Habitat for Humanity volunteering drywall mudding and sanding, then 1 day repairing own home drywall.

Location: Homeowner’s own home.

Used: Westpac Materials Taping and Topping Compound “TNT” purchase date 9/22/2005 first opened 6/6/2015. Consistency: firmer than fresh premix, about like “Play-doh.” Thinned out with small amount of water for test use. Color: light tan.
Comparison: Sheetrock Brand All Purpose Joint Compound purchase date 4/7/2014 first opened 2014. Re-opened 6/7/2015. Consistency: moist paste, unthinned. Color: white.

Testing : 5/8” scrap drywall removed from damaged wall, painted side down, cut it half, separated by 1/8” gap, screwed down to scrap wood. 6/13/2015 Photo labels:
“1”: 6/6/2015 gap filled with 9/22/2005 mud.
“2”: 6/7/2015 joint taped with 2005 fiberglass tape topped with 9/22/2005 mud.
“3”: 6/8/2015 top layer 9/22/2005 mud.
“2005” left: 9/22/2005 mud top half inch layer discarded: grey/brown/black speckled/discolored, faint musty smell disappeared after 24 hours, no odor thereafter.
“2005” middle: 9/22/2005 mud after top half inch scraped off.
“2014” right: 4/7/2014 mud for comparison

Results: So far only difference I can tell between 9/22/2005 mud used on test materials and 4/7/2014 mud used for 6/2015 repair to my house is slightly tan color, less apparent when dry. Otherwise seems to work ok. No noticeable odor when dry.

Comment: use at your own risk. I am not a professional. I would not use obviously smelly / moldy old mud described by others. Results may be more favorable due to ten year old mud never having been opened.
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Old 06-13-15, 04:57 PM
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Join Date: Mar 2005
Location: USA
Posts: 43,810
Joint compound won't necessarily go bad as long as it's kept sealed and doesn't dry out BUT as cheap as the mud is with the propensity for old mud to have trash in it [dried specs of mud] it's usually best to go ahead and buy new.
Old 06-13-15, 05:10 PM
Join Date: Oct 2008
Location: New England
Posts: 9,995
Hi Cnam and welcome to the forum,
If you were going to give a garage a single coat of mud and tape, it would probably be just fine. But as Mark said, for the cost and potential of chasing little imperfections, I would toss it. Even while applying mud, I often discard what accumulates on the hawk and reload with new. I rotate using the 4 sides to clean my knife and don't reuse anything that is questionable. I dread making that last final perfect pass and suddenly there is a streak down the middle.

Old 06-13-15, 05:27 PM
Join Date: Jul 2003
Location: California
Posts: 1,722
IF your time is worth anything then you spent more in time on your experiment than new, fresh mud would cost. Now if it was a major trip to town to get material vs. using what you have it might be justifiable.

Did the stuff on your scraps get hard when it dried?
Dis it stick well to the board?
Did it homogenize nice and smooth or where there lumps, even soft lumps, in it?

If there was any mold at all in the old mud you run a risk of introducing it to your wall. If it gets wet you will get a mold bloom.
Old 06-15-15, 07:45 AM
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 18,651
Mud is just too cheap - buy new.

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