Joint compound comes in larger containers than I need. I have had this problem for years where storing opened but unused joint compound leads to mold growth, usually starting within a week or two. I'd like this to not happen, or at least extend it to months or years, so I don't need to keep throwing away 95% full containers and buying new ones.
The only thing I've really tried is storing it in the fridge after opening. This has inconsistent and limited effect.
On rare occasions I have been able to store it for extended periods of time with no mold growth but I was never able to determine how I did that, and upon opening and reclosing those particular containers mold started to grow anyways.
So, my question is, how can I make unused joint compound last longer?
- Are there precautions I can take during use to reduce contamination?
- Are there ways I can store it to reduce growth?
- Are there mold killing additives that won't affect its usefulness?
- Are there certain brands or types I can look for that are less prone to mold growth?
Often any molds that grow seem to be mostly in the surface, the joint compound underneath usually seems clean, but I never really want to deal with that mess.
Best Answer
Mold grows on any surface that provides food for growth. Joint compound contains organic compounds and lots of moisture. The compound will only last a finite length of time even under "ideal" conditions (if mold spores don't ruin it drying-out will).
To slow down its' expiration time: when storing the compound for any length of time, place the plastic that was included with the compound so it completely covers the top layer. Next, soak a rag in a mixture of 1 gallon water to 1 tablespoon of bleach. Wring it out and place it on top of the plastic. If the lid for the bucket doesn't have a rubber seal place a plastic trash bag on the rim of the bucket and seal tightly with a mallet.