Drywall: Applying Compound

Applying drywall compound seems like it should be easy but getting a smooth finish can be harder than it looks. However, with a few simple tips, you’ll be able to master the technique in no time.

Drywall compound has a few different names like joint compound and drywall mud but it’s all used for the same thing, smoothing out your walls and hiding seams and screw heads. The first thing you’ll want from mudding drywall is the mud itself. Drywall compound is available as a powder to mix with water. But get the ready mix joint compound, it’s definitely easier to use and more popular even with the pros.

You don’t need to add water or a powder to a ready mix mud but it can be a little stiff and lumpy when first opened, so it’s a good idea to stir it up a little. Use a pilot drill with a whip attachment to stir the mud right in the bucket. Be careful you don’t over stir it though or you can get small air bubbles in the mud which can create imperfections later. You’re looking for the consistency of creamy frosting.

Here’s a tip. Joint compound tends to dry out once it’s been open, so keep the lid on your bucket of mud tightly closed when you aren’t using it and try to use up the entire bucket once it’s open as the mud will dry out in a few weeks, even with the top on.

Drywall mud is applied in three coats. The first coat, when tape is applied to the seams is called the tape coat. Spread a coat of mud over each seam using a six-inch taping knife. This will act as a base coat for the drywall tape. The real secret to a smooth wall is just spread the mud with wide taping knives using a wider knife with each coat. This will help feather out the edges of the mud and provide a smooth seam surface. You’ll want to use a paper drywall tape for this project. It’s great for hiding and reinforcing the seams. Fiberglass mesh tape is best to use for small patch jobs as it can shift and crack when used on seams. Cut the paper tape to the right length and then gently press it into the joint compound with your hands or taping knife while the mud is still wet. Then spread another light coat of mud over the drywall tape. You’ll still be able to see the tape through the mud but don’t worry, that’s exactly what you want. Remember, the goal is to create a seamless wall, so use your blade to get each layer of mud as smooth as possible.

Mudding inside corners is a bit more difficult but don’t sweat it. Just use a six-inch taping knife or a corner taping trowel to apply mud to the seam. Then cut a length of paper tape and fold it in half before pressing it into the mud. Add another layer of mud over the tape just as before. When doing outside corners with a corner bead, hold your knife at a 45 degree angle to spread the mud over the bead. Once all the seams are taped and mudded, use a little more compound to cover the screw heads then let everything dry for 24 hours. Once the mud is dry, feel free to lightly sand any large blemishes.

Now, it’s time to apply the second or fill coat. This will hide the drywall tape and smooth the seam. This time, use a 10-inch taping knife. Spread the wider coat of mud over the first building up the center to strengthen the seam. The mud should extend two to three inches beyond the width of the tape. For the corners and screw heads, you want to extend three to four inches. You’re finished with the fill coat when the drywall tape has disappeared. Let the mud dry for 24 hours. Again, you’ll want to sand away any large blemishes.

Now, it’s time for the final coat of joint compound called the skim coat. This coat will fill any small imperfections and finish the edges to create a nice seamless surface. Since this is only a skim coat, you won’t need to use as much mud, using even wider 12-inch taping knife to spread the final coat. Carefully feather the edges out about another three inches pass the previous dry compound on either side. Spread the mud eight to 12 inches out at the corners and six to eight inches around the screw heads. You should end up with a nice, smooth finish that looks and feels level with the rest of the wall. Let this last skim coat dry for 24 hours and then sand away any remaining imperfections.

Mudding drywall can be one messy job but it’s hard to beat the feeling of satisfaction you’ll get when you’re looking at those nice, smooth walls. Happy mudding!