Can I Use Old Drywall Compound? [What You Need To Know]

You’re about to start a drywall project, and you notice there’s some old drywall compound left over from a previous repair. Can you use it or do you need to buy a new one?

As long as Drywall compound is properly sealed and stored, you should be able to use it. Once Drywall compound bucket is opened, it has a 9 month shelf-life. It’s, however, highly recommended to confirm the quality of your compound each time you want to use it to check if it has mold or it has dried up.

The answer to this question depends on how old the drywall compound is and its condition. If the drywall compound is old, it’s probably best to buy new. Over time, drywall compounds can harden and become difficult to work with. Even if it’s still soft, it may not adhere as well to the wall or sand as smoothly. However, it’s most definitely possible to use old Drywall compounds when certain conditions are met. 

What Is Drywall Compound?

A joint compound is also known as drywall mud and mastic. It’s a white powder of mainly gypsum dust combined with water to create a paste of the consistency of cake frosting. The drywall compound can be used with fiber or paint drywall tape to seal joints, offering a seamless base even if it doesn’t stick on plywood.

Drywall mud can be considered as a glue that keeps two drywall sheets together. You can use it to cover joints, seams, or screws. Using joint compounds after installing drywall sheets is of utmost importance. It offers a smooth surface without any imperfections, making it easy for you to paint or wallpaper your walls.

There are different types of drywall compounds available in the market. As no two types are the same, it’s probably better to learn about these variations before making a purchase and how much Drywall mud you’d actually need for your project.

Quick-Setting Compound

Quick-setting compound or hot mud is an ideal pick for you if you want to finish a drywall job quickly or if you have to apply multiple coats of joint compound on the same day. You can use this variation to fill deep holes and cracks in plaster and drywall, where drying duration can become a problem.

Several factors can affect the lifespan of drywall. Air pressure, temperature, and humidity are the most important things to consider. Regular drywall won’t dry quickly if you live in an area with higher humidity. In that scenario, you can use the quick-setting compound to ensure a proper level 4 or 5 drywall finish.

Taping Compound

The taping compound is perfect for covering plaster cracks and applying drywall tape. You can use this type of drywall mud to finish the first phase of drywall installation. However, this one dries harder and is quite difficult to sand. 

You can use a taping compound where superior crack resistance and bonding are required, such as around window and door openings. This one is also an excellent option if you want to laminate drywall sheets in multiple-layer partitions.

Topping Compound

Another drywall compound variation that deserves a spot on our list is the topping drywall. Once you use 2 coats of taping compound over taped joints, you can use the topping compound. It’s a relatively low-shrinking drywall mud that provides an excellent bond.

Generally speaking, you’ll get this compound in powder shape. Afterward, you can mix it with water to create an adhesive paste. Yes, it makes it less convenient. However, this approach increases the lifespan of your compound, allowing you to store it for future use.

All-Purpose Compound

True to its name, an all-purpose compound can be used for any phase of drywall installation: from covering seams to finishing drywall. It’s a premixed compound sold in boxes and buckets. This one is lightweight and has a slower drying time than other variations.

An all-purpose compound is an excellent pick for you if you are a beginner. It’s fairly convenient to work with and is considered an excellent pick for DIYers. You should apply at least the first 3 layers of all-purpose drywall compound to get a smooth finish. 

Is It ok to Use Old Drywall Compound?

Drywall compound has an amazing shelf life. Generally speaking, it won’t go bad as long as it’s properly sealed and stored away from contamination. So, you can use an old drywall compound if it has never been opened. 

That being said, like all other products, several factors will influence the quality of a drywall compound, such as:


We all know moisture is bad for drywall. As your drywall sheets are porous, moisture will seep through them, making them soft and weak. However, when it comes to drywall mud, putting a thin layer of water on top of it is recommended.

With the passage of time, drywall can dry out, which is not a good thing. If you want to store your compound for longer, never put the drywall mud back in the bucket or stick a dirty knife in it. 


Once you open the bucket, the drywall compound can expose several contaminants, including microorganisms. So, when you store it again, the result might be mold growing on the mud – especially if you use a regular compound.

Fortunately, you can get a mold-resistant drywall compound as well. This variation is usually used in places where moisture can damage the drywall, such as kitchens and bathrooms. This type of joint compound will definitely last longer, but mold will reduce the overall quality of the compound.


For drywall compounds, the air is the most significant problem. The drywall compound will eventually dry out if exposed to air, making it unusable. Sometimes, only the top layer of drywall dries out. In that scenario, you can remove the first layer and use the rest of the mud!

What Happens If You Use Old Drywall Compound?

Well, it depends upon the quality of the drywall compound. If you have never opened the bucket and it has never been exposed to air or contaminants, you can use an old drywall compound without any worry. 

Alternatively, if you did open the bucket but stored the compound, you will need to confirm the quality of your compound. You shouldn’t use it if it’s dried out or has mold. Otherwise, the mold will ruin your entire drywall. 

In addition, an old drywall compound won’t be as adhesive as the new one. This means it won’t be able to provide a satisfactory bond. So, u might end up wasting drywall tape as well!

Does Drywall Compound Go Bad?

Yes! Although drywall compound has an extremely impressive shelf life, it cannot last forever. So, it will go bad eventually. The drywall compound can last for years if you have never opened a bucket. Otherwise, contaminants can lead to mold growth, or air can dry out joint compounds, making them unusable in the future.

How Long Can You Keep Drywall Compound?

After opening, the drywall compound can last for up to 9 months – if stored properly! If not stored airtight, drywall mud will go bad in days. This is because the premixed drywall compound has moisture, providing an excellent place for mold survival and growth.

Furthermore, if not kept airtight, drywall mud can dry out due to evaporation. Generally speaking, the actual lifespan of the joint compound depends upon the manufacturer and the quality of the material. So, don’t forget to check the manufacturer’s website to determine the actual shelf life of drywall mud.

Alternatively, if you have never opened a bucket of drywall compound, you shouldn’t use it after the expiration date mentioned on the packaging. You can always look for signs indicating a drywall mud has gone bad: as discussed below!

How to Know If My Drywall Compound Has Become Unusable?

There’s just no way around the fact that drywall compounds will eventually decompose. It can go bad due to mold growth or dryness. When it does, you’ll notice the following changes:

Foul Smell

The foul smell is the most significant sign that drywall mud has gone bad. All drywall compounds have a unique aroma, regardless of the manufacturer and type. Once the compound has expired, it will produce a strong odor different from its original aroma.

The normal odor of a drywall compound is quite hard to describe, but it’s similar to chalk dust. Although the chalky smell is itself considered bad, the foul smell will be even worse. Due to decomposing, your drywall mud will produce a smell similar to rotten eggs or roadkill.  


If not kept airtight, the drywall compound will dry out. You cannot use dry drywall mud as it does not provide a superior bond and adhesive qualities. Sometimes, when you store a drywall compound, only the upper layer of the compound dries out. In that scenario, it’s totally ok to use the rest of the compound as long it has no foul smell.

Signs of Mold

Mold particles are commonly available in the environment. All they need is a place to survive and grow. As moisture provides an ideal place for mold growth, an opened bucket of drywall compounds will eventually become moldy.

To protect your investment, you can use chlorine bleach and/or dish soap (just make sure not to use it on Vinyl Flooring) to restart the mold formation in the bucket of the joint compound. That being said, if you have mixed water in your drywall mud, it’s not recommended to store it at all.


If you are still unsure whether your drywall compound is usable, look for discoloration. Generally speaking, drywall compounds come in white color. However, it might differ depending on the manufacturer and type of compound.

If your drywall compound has patches of green or yellow color, it means the drywall mud has become unusable. 

What Can I Use Instead of Drywall Compound?

If, for some reason, you don’t want to use a Drywall compound, your best bet is the Spackle compound. While the drywall compound is made primarily of gypsum dust (which might make you sick if you aren’t too careful) and limestone, the Spackle compound contains gypsum powder and binders.

Compared to the drywall compound, this one is thicker and has the consistency of toothpaste. Spackle compound is also available in different types, including:

  • Epoxy Compound – This variation is perfect for outdoor use. It’s an oil-based filler that can be used to repair cracks, gouges, holes, and other imperfections.
  • Acrylic Compound – Acrylic spackle compound is flexible like vinyl and can be used outdoors. You can use it on plaster, drywall, wood, brick, and even stone.
  • Vinyl Compound – You can use vinyl spackle compound to fill in cracks and holes up to 3/4-inch deep. It’s usually applied in multiple coats and is quite easy to sand.
  • AllPurpose Spackle Compound – Just like all-purpose drywall compounds, spackle compounds can be used in all phases of drywall installation. Ideally, this compound is used to repair larger cracks, gouges, and holes.
  • Lightweight Compound – This type of spackle compound is only designed for small, quick fixes. It contains an adhesive and sodium silicate that can be used for repairing cracks, holes, and smaller dings. 

Although the spackling compound is an excellent alternative to the drywall compound, it should be your first choice. This material is designed for smaller repair jobs. You cannot use it for a drywall installation project. 


How to Dispose of Old Joint Compounds?

Old drywall compound is not actually a hazardous material. You can put it out with your normal trash or dispose of it at the construction and demolition drop-off center. That being said, drywall compound is not an environment-friendly product either. It contains a high concentration of VOCs, mercury, and sulfur. So, make sure to dispose of it as soon as possible.

How Long Does Unopened Joint Compound Last?

An opened premixed drywall mud can last for around 1 year if stored in the right conditions. Alternatively, if you have invested in drywall compound powder, the product can last forever. All you need to do is store it away from direct sunlight and extreme cold and heat.

Does a Fan Help Drywall Mud Dry Faster?

Yes, the breeze generated by a fan will reduce the humidity levels in a certain area. This practice improves air circulation and helps drywall mud dry faster. Besides a fan, you can also use a dehumidifier or heater. In addition, you can even use a clothes dryer on “Hot” to speed up the drywall mud drying time. 

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