Does Drywall Mud Go Bad?

Finishing off a wall with drywall mud is supposed to be relatively simple, but if your mud looks or smells strange, it can be off-putting and may make you concerned. So does drywall mud go bad?

Drywall mud does go bad under certain conditions. Improper storage or simple expiration can make the material hard as stone or deteriorated to the point of no longer being usable.

It may even develop dangerous mold. Bad drywall mud shouldn’t be used and should be disposed of properly.

Here’s what you need to know about drywall mud spoiling.

How Drywall Mud Goes Bad

Drywall mud – otherwise called drywall joint compound – is made of gypsum, an abundant mineral that reacts with limestone and talcum powder, as well as clays and starches to form a thick material that closely resembles natural mud.

This mud usually contains water, which, combined with the organic materials and mixed with air, can invite mold development.

Black mold, which is particularly toxic and dangerous, is common in bad drywall batches.

Even if it doesn’t grow mold, exposed drywall mud will invariably dry up and become hard as stone, as it’s supposed to do when in use. This can make it completely unusable.

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How to Keep Drywall Mud from Going Bad

Keeping your drywall mud from going bad is relatively simple.

  • Check the expiration date on the mud. Most drywall mud has a shelf life of about 12 months, so be sure that you’re buying and using it within that time frame.
  • Store your mud in an airtight container. Its packaging will probably be airtight, but if you have any leftover after use or live in a particularly humid area, you’ll want to put it in a sealed container.
  • Keep your mud cool and dry before and after use.

Drywall Mud FAQ

Here are some of the most frequently asked questions about drywall mud going bad.

How can you tell if your drywall mud is bad?

Bad drywall mud will show fairly obvious physical signs. It will either be dry or slimy. It may change color or become patchy. In the case of mold, your drywall mud will probably develop a strong, unpleasant smell.

Can you use expired drywall mud?

No, you should never use expired or spoiled drywall mud. Doing so might endanger your project’s integrity. It may even be dangerous for your health in the long term.

What should you do with expired drywall mud?

If you have a large exterior trash can, dispose of the bad mud batch there immediately upon discovery. If not, consider disposing of it directly at a local dump or in smaller batches over time.

Can you use drywall mud on wood?

Find out in our article on that very topic.


Drywall mud is a useful finishing tool for just about any project. If it goes bad, though, it’s often more trouble than it’s worth.

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If you find yourself suspicious of your batch of drywall mud, it’s probably better to be safe than sorry. Dispose of your old batch and get a fresh one for your project.