Why Does Your Drywall Mud Bubble?

Giovanni Valle is a licensed architect and LEED-accredited professional and is certified by the National Council of Architectural Registration Boards (NCARB). He is the author and managing editor of various digital publications, including BuilderSpace, Your Own Architect, and Interiors Place.

Bubbles in drywall mud aren’t only unsightly and annoying, but it often seems like they’re impossible to prevent. Whether you’re a skilled tradesperson or someone doing DIY work on their home on the weekend, you may be wondering to yourself, “why does my drywall mud get air bubbles?”

Your drywall mud bubbles when it’s applied to a painted drywall surface. Because the painted surface is sealed, the bubbles in the drywall mud escape through the mud’s surface. To prevent air bubbles from forming, mix your drywall mud properly, only use fresh drywall mud, and apply correctly.

Keep reading to get more information on why your drywall is bubbling and how you can prevent this from happening.

Is There a Difference Between Drywall Mud and Joint Compound?

Let’s start by clearing up a common question for those who might be new to installing drywall: is there a difference between drywall mud and joint compound? The answer is no. They’re just different names for the same thing. If you read anything online talking about joint compounds, know that they mean drywall mud.

Why Does My Drywall Mud Get Air Bubbles?

If you’re asking yourself this question, you’re not alone. It’s a common problem when installing drywall, but knowing the causes as to why your drywall mud gets air bubbles will help you to understand the solutions.

Drywall mud bubbling will only occur when applying the mud on a surface that has already been painted. Unpainted drywall is porous, and it’ll allow any of the air bubbles in the drywall mud to escape through the paper and back into the rock. However, a painted drywall won’t do this, and any bubbles in the drywall mud will escape through the surface.

When applying drywall mud to a previously painted surface, using too thick a layer or not properly scraping it can also add air to the drywall mud and cause bubbles.

If you mix drywall mud incorrectly, it can also cause bubbles because overmixing can add in pockets of air.

One final reason drywall mud can bubble is that you didn’t properly prepare the surface you’re applying it to. You need to make sure you clean all of the drywall dust off first because any left on there can get trapped under the mud and cause unsightly bubbles.

How Do You Prevent Bubbles in Drywall Mud?

Thankfully, there’s a wide range of solutions to help you prevent annoying drywall mud bubbles. Different solutions may work for different installation jobs, so if any of the tips in this article don’t work for you, keep trying until you find the perfect fix.

How You Mix Your Drywall Mud Matters

When it comes to bubbles in drywall mud, you can solve the problem a lot of the time by just changing the way you’re mixing your drywall mud.

If you’re using a rapid-setting mud, make sure you’re only mixing up small batches at a time because otherwise it’ll dry too quickly and become impossible to use correctly. There are some slower drying alternatives that you can consider if you find you’re constantly having to deal with this problem.

You also need to ensure you’re not over-mixing the mud, as this can trap air inside the mixture which will cause bubbling when applied. When using a drill to mix your drywall mud, don’t have it on a very high-speed setting as this will add too much air to the mixture.

Additionally, don’t use a plunging action when mixing the mud, as this too will suck air into it. The best way to mix drywall mud using a drill is to have it at a moderate speed and keep the paddle in the mixture until it has finished mixing.

Another thing to consider is using a different kind of drywall mud. Many in the business recommend mixing the drywall mud yourself from powder instead of relying on the premixed mud. Mixing it yourself means that you have more control over the consistency and can avoid the premix problem of it taking forever to dry because of its additives.

You can also do things to change the consistency of your drywall mud to make it less likely to bubble. A thinner coat is much less likely to bubble as it goes on smoother, and it’s easy to push out any air bubbles in it during application. You can thin your drywall mud by adding some water to it, but make sure you’re not adding too much as drywall mud that’s too thin is useless as well.

Check That Your Products Are of Good Quality

Sometimes, the problem causing bubbles in drywall mud is the products you’re using. Make sure that you’re only using fresh drywall mud, as a bad batch can cause bubbling. The same thing applies to a bad batch of finishers.

Testing if your drywall mud is of good quality is easy: simply scrape a small patch of drywall mud on a clean area of the wall and try to scrape it off. If it doesn’t budge, then you know that you have good drywall mud.

Also, aim to avoid using drywall mud that has been sitting around for a long time. The older it is, the more problems you’re going to have with it. There may be air bubbles in the mud, or it may not go onto the wall as smoothly anymore.

Change the Way You’re Applying Your Drywall Mud

Many contractors will agree that the best way to prevent drywall mud bubbling is to apply it in a certain way. If you’re inexperienced, it’s easy to make mistakes when applying the drywall mud, such as using too much or not scraping it properly.

Before you apply your drywall mud, fold it with the knife in the tray for a few minutes. This will eliminate many of the air bubbles that may have built up during the mixing stage.

Changing the way you apply your drywall mud can also help to prevent any bubbles. The key is to apply more pressure when scraping the mud, as this will get rid of any bubbles that rise to the surface.

Below is the best way to apply drywall mud:

Only use a thin layer when applying it to the wall.
Apply the first layer, which is the base coat.
Scrape this layer tightly at a 45-degree angle.
Apply the second layer to hide the joint.
Wait a few moments to see if any bubbles form; then scrape this layer tightly at a 45-degree angle.
Apply the third layer to make sure there are no bubbles that remain on the surface.
Sand the drywall mud.
Apply one final, tightly scraped layer.

Can You Use Dish Soap in My Drywall Mud?

This is a common solution when searching for an answer to “why does my drywall mud get air bubbles?” The consensus on whether or not it’s okay to add dish soap to drywall mud is a pretty divided one.

Many swear by it, saying that not only does it make the drywall mud “creamier” and easier to apply, but it also makes the tools much easier to clean at the end.

On the other hand, some say it’s a terrible idea, that it’s likely to cause problems with the drywall mud not adhering properly to the surfaces and peeling off later on.

All in all, the answer seems to be that it’s a personal choice, but if you do use it, you should only put in a very small amount.

Why Does Your Drywall Tape Blister?

One thing that’s just as annoying as drywall mud bubbling is drywall tape blisters. Most of the time, it happens because of errors caused by inexperience, so it’s important to understand exactly what you’re doing before applying the tape.

A common reason drywall tape can blister is that there has been too much drywall mud scraped away from under the tape. Pressing too hard with your knife will cause this, and not only will it likely cause the drywall mud to bubble, but it means that the paper tape won’t properly adhere to the wall and might separate later on.

If you encounter this problem, it’s best to remove the tape and start again. You can either remove just the affected section or, if the problem affects all of the tapes, just start all over.

Another problem caused by pressing too hard on the drywall tape with your knife is puncturing it, which can cause blistering as well. This blistering occurs because the tape absorbs moisture from the drywall mud upon the application of the second layer.

Final Words

Drywall mud bubbling is annoying, but it’s an easy problem to prevent as long as you understand why the bubbles are occurring in the first place. Always make sure to prepare your drywall mud properly, using only good-quality products. Then, when it comes to applying the drywall mud, the secret is in using thin coats and scraping it firmly.