Why Does Drywall Mud Get Moldy? Let’s Fix It!

Drywall Mud (joint compound) mold is a common issue. Mold damages the mud, and if it affects heavily, it can not be workable. 

So the question is, why does drywall mud get moldy?

Mold has life, and it needs food to survive. Joint compounds have the materials for staying alive for mold. Generally, after using a bucket of mud, if you do not clean the bucket properly and without the proper way you cap/seal the bucket, the drywall mud gets moldy fast. 

There are more other reasons which are the cause of moldy mud. I will describe it below. Also, I will give you some tips about drywall mud store protection.

1. Can moldy drywall mud be used?

It is a tricky question. It depends on your mud condition. If the mold starts separating in mud, take a putty knife and remove the top layer of mud. 

If you think mold separates too much in a bucket, throw away the mud and buy a new bucket of mud. 

However, I always suggest taking a new bucket of mud for work. Because the mud price is not very high, it will give you confidence in your work, and the fresh mud will be better than the moldy mud. I ask you one question, do you like to use moldy materials on your walls?

You can check: Why drywall mud peeling after paint.

2. Should I replace moldy drywall mud?

I have already answered the topic. If you think your mud is not very affected by mold, remove the top layer of mud and use it. 

Moldy mud is already rotten, although it is lower affected or higher affected. If you take fresh mud, its condition will be good, and you won’t feel bad in the future.

Also, drywall mud is cheaper. So don’t hesitate to replace the mud. Use a new one and stay safe.

3. Why is my joint compound turning brown, green, or black?

If you see a small spot in bucket mud that turns brown, green, or black, there is a high chance it is mold. 

The small spot grows day by day and separates every area on the mud. And the mud completely gets wasted and releases very bad smells like rotten eggs.

You should not use this mud and leave it away. Take a new bucket of mud for your project. 

4. How long does drywall mud last after opening?

It is a very tricky question to answer. Different experts suggest the drywall mud within 9 months after opening. But from my experience, you should not store the used mud for a long time. 

Try to finish mud as soon as possible because there is a risk of mold storing. There are many reviews that after opening mud, it gets mold within 1 month. 

If you plan to use mud a long time later, use it all or share it with your neighbor who needs it. Buy a new one when you need it. Joint compounds are not expensive things. 

5. How to kill mold in drywall mud

They have a lot of options to kill mold in drywall mud. You can use hydrogen peroxide, Tea tree oil, vinegar, baking soda, grapefruit seed extract, etc. But I don’t recommend it because it sounds too expensive. And not give mud fresh quality back.

If mold separates in a small place, I suggest taking a putty knife and removing the affected mud. If it separates the majority area, don’t use the mud. That’s it.

6. What is the main cause of mold growth?

We know mold has life. If the mold gets the right food, water, and air, it can live and grow fastly. 

In mud, different organic materials can provide food for mold. Also, other reasons are responsible for this. For example, 1. There is a lot of humidity 2. Not properly clean the bucket after using mud 3. The mud bucket is not properly sealed for air, and for more reasons, mold grows faster. 

To protect the mud from beginning against mold, you need a clean and dry environment and seal the bucket cap properly.

7. Can I keep protecting my drywall mud from molding?

Yes, it is possible, but you only do it from the beginning. 

You should follow different methods for keep protect your drywall mud from molding. Example dry compounds, isopropyl alcohol, bleach, chlorine tab, vinegar. 

Below, I will explain how to apply the methods.

8. How to keep my drywall mud from molding

Primary level after completing your mud project, you have to scrape off all dry compounds from the bucket top, side, and under properly. 

To store mud, use a plastic bucket. It can protect your mud against different types of bugs. 

When your bucket is properly clean, You can follow the below methods that can be helpful.

Dry compounds

If you work with dry compounds, I suggest you do not wet all compounds at once because dry compounds have a very low chance of effect with mold.

Use a small amount at one time. When you need more, prepare the little dry compound again.

So they have a very low chance of being wasted. 

Isopropyl alcohol

Isopropyl alcohol has a good ability to protect against mold. 

After completing your bucket, take isopropyl alcohol in a sprayer, then spray it all over the used mud. Then seal the cap of the bucket properly. 

Alcohol provides good protection for a long time.

Bleach powder 

You can use bleach powder for a slower mold process.

First, seal the plastic bucket properly.

In one gallon of water, take one tablespoon of bleach powder. Take one rag, and soak it in the water. Then wrap the rag over the bucket cap with a rope. 

Now the mud can be stored.

Chlorine tab

Chlorine tab is also useful for storing mud.

First, properly clean the mud bucket. Then put a chlorine tab with a filter in the mud bucket. Then seal the cap of the bucket. Make sure to clip a corner to leave chlorine gas. 

This method is very effective, and mud will last longer.

Vinegar

Vinegar can be useful. But it has some acidic impact. It changes a little color but not much. Still useful.

You can pour a little vinegar into the basket. Then seal the cap properly. It kills mold and gives mud extra life for the store.

Conclusion

Mold can ruin your joint compound. For just some extra step, you can save it. I hope now you have enough knowledge about mold. And how to take care of the issue.

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