Can Drywall Mud Go Bad?
It may not have an expiration date like milk, but yes, drywall mud can expire
Drywall mud can go bad by getting moldy or drying out.
Powdered drywall mud is more likely to stay “good” than premixed joint compound.
If there’s mold in your drywall mud, it can cause health problems.
Always store drywall mud in a dry environment, and don’t open it until it’s time to use it.
While it might not have an exact expiration date, drywall mud can go bad—especially if you’re using the wet, premixed kind (and especially after you’ve already opened it). If, however, you’re using the powdered kind, proper storage can help ensure it stays good for months or even years. Let’s explore what causes drywall mud to deteriorate and how to keep yours fresh for as long as possible.
What Makes Drywall Mud Go Bad?
If you buy powdered drywall mud, you’re basically purchasing a bucket of gypsum sand (and other additives, depending on the type of drywall mud you’ve purchased) that you have to mix with water. That is, after all, how you make a dry substance into a muddy one.
Premixed drywall mud or joint compound, as its name suggests, already has water mixed in. For that reason, it can have a shorter shelf life—because the presence of moisture is what causes drywall mud to deteriorate.
How Does Drywall Mud Go Bad?
The primary way you can tell your drywall mud is bad is the visible presence or smell of mold. Premixed drywall mud, which already contains water, is more likely to grow mold more quickly, particularly once you’ve opened it.
Powdered drywall can also grow mold—or set up in the bucket—if it’s exposed to moisture. Most powdered drywall mud is stored with a plastic liner meant to prevent moisture exposure, but it can still happen, especially if you store your buckets for long periods of time in humid areas.
How to Keep Your Drywall Mud Good for Longer
Some people claim that powdered drywall will stay usable forever so long as it stays bone dry, while others have found mold growing in an unopened (but long-stored) container. The most important thing is to keep your powdered drywall mud as dry as possible for as long as possible. So if you’ve opened the container, consider lining it with another layer of plastic lining before resealing it.
For wet drywall mud, there’s less you can do to keep it good for longer, so don’t expect an open container of it to last more than a few months or so. Just make sure the container it's in is sealed very well and you store it in a dry place.
Fortunately, drywall mud tends to be relatively low-cost, so you don’t have to stockpile it. If you have more questions or just don’t want to worry about DIYing a messy and demanding project, a drywall repair pro near you can help.
If your premixed drywall mud is dried out or has begun to set in the bucket, you may be able to revive it by adding warm water and stirring. However, the first and most important step is to scrape off any hard, dried bits of drywall that may have accumulated toward the top of the container and throw them away because they will not easily reconstitute back into the drywall mud mix.
Yes, drywall mud can get moldy—though the presence of moisture is required for this to happen. That’s why the best way to keep your powdered drywall mud fresh for as long as possible is to keep it in dry storage conditions. If you live in a humid area, it might not make sense to stockpile a lot of powdered drywall mud before you’re ready to use it. As for premixed drywall mud, avoid opening the container until you’re ready to use it—and don’t expect it to last longer than six months.
Yes, if there is mold in your drywall mud and you then use it to build walls in your house—or if mold develops in your set drywall, like it can in hot and humid areas—it can lead to illness. Mold in your drywall (or other parts of your home) can make existing respiratory conditions or allergies worse, and the effect can be more intense for those who have existing health issues or compromised immune systems.
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