Joint compound, or drywall mud, is a building material similar to plaster. Finishers use it to seal joints and hide screw heads after a drywall installation. Many types of drywall mud exist, but most finishers rely on all-purpose, ready-mixed joint compound, which comes in 5-gallon buckets. The slow drying time allows finishers to complete a project before the compound becomes unworkable.
Ready-Mixed Joint Compound
Allow ready-mixed joint compound to dry for about 24 hours after you apply it. When it is wet, it is gray; when it is dry, it is white. Heavy applications take a long time to dry, so only apply as much joint compound as necessary. If the weather outside is dry, open doors and windows to bring in fresh air. Position fans at one end of the room so air will move quickly in and out. If the outside air is humid, close the doors and windows and set up dehumidifiers. Generally, the faster the air moves, the quicker the evaporation process will be.
As ready-mixed joint compound dries, it becomes unworkable. Typically, you have 10 to 15 minutes to smooth joint compound after applying it. After that, the compound tends to streak when wiped, leading to a rough texture that will require heavy sanding later. In low-moisture or high-heat environments, you may have just a few minutes before the compound is difficult to work with.
Apply no more joint compound than you can handle within a few minutes. Don’t apply joint compound over large areas or you risk compromising its smoothness. For example, if you are covering a long joint, finish one half at a time rather than trying to coat the entire joint at once.
Setting-Type Joint Compound
Setting-type joint compound has a different chemical composition than ready-mixed joint compound. Rather than drying through evaporation, setting-type joint compound dries through a chemical reaction, as concrete does, so the drying time is more predictable. Setting-type compounds are available with a variety of specified drying times, from five to 90 minutes, making it convenient for projects with tight deadlines. Follow the manufacturer’s directions for mixing to ensure the setting-type joint compound dries within the specified time frame. The color of setting-type joint compound may not change as it dries, so poke a few areas gently to determine if the surface has hardened.
- Photo Credit Hemera Technologies/AbleStock.com/Getty Images
How to Use Joint Compound
Joint compound does what its name implies - it fills joints between drywall. Here's how to use it correctly, as well as...
How to Texture Walls With Drywall Mud
Walls textured with drywall mud can add beauty to your home. Buy special texturing tools or use a broom, dry brush or...
How to Seal Threaded Plumbing Pipes
How to Seal Threaded Plumbing Pipes. There are two ways to seal plumbing pipes. The first way is to use Teflon tape....
How to Apply Drywall Mud
Drywall mud, or joint compound, is used to smooth joints in walls and ceilings before they're painted or wallpapered. When it's properly...
How to Dry a Water-Damaged Ceiling
If your ceilings have water damage, you need to remove the drywall and let the inside of the ceiling dry out. If...
How to Dry Drywall
Drying minor water damage to drywall is possible if you attack it immediately before the drywall swells and the seams began to...
How Much Mud Per Sheet of Drywall?
To transform a wall of individual drywall panels into one continuous smooth surface, the drywall contractor fills the seams between the panels...
How Long Can You Keep Drywall Compound?
While you can technically save drywall compound for years in the right conditions, the reality is that most of the time the...
Applying Mud to Drywall
Mud needs to be used on drywall before it's taped. Learn how to add a new bathroom to a home, including tips...