Pick and Prepare Joint Compound

Learn how to choose and prepare joint compound

by Patrick McCombe

Contrary to what most people think, ready-mix joint compound is not ready to use straight from the bucket. It needs to be mixed for the compound to spread evenly, which leads to a professional-looking finishing job with less sanding.

Ready-mix compounds are available in several versions. At home centers, you’ll find regular and lightweight all-purpose compounds. At drywall-supply stores, you may also see taping, topping, and ultralight compounds. I’ve found that regular-weight all-purpose compound works fine for most drywall-finishing projects. Lightweight all-purpose compound is a good option when you have to carry a lot of compound far from the truck, but it’s softer when dry, which makes it susceptible to damage. Lightweight compound sands more easily than regular compound, however, so if you’re new to finishing, it’s worth a try.

Powdered setting compound, which is mixed with water before use, hardens chemically, making it a better choice for patching holes, for thick applications, and for the tape coat. It is also stronger and doesn’t break down with exposure to water, making it good for bathrooms and other wet areas. Don’t, however, dump it down the drain when cleaning up.

Most lumberyards and home centers have setting-type compounds with 45- and 90-minute set times, but drywall suppliers often have compounds available with set times from 5 to 210 minutes. The number on the bag is the average time that it takes for the compound to firm up enough to apply another coat. This time can vary with temperature and humidity.

Preparing both ready-mix and setting-type compound is an important first step in becoming proficient at drywall finishing.

Step by Step: Preparing ready-mix compound

Step 1 Pop the top. A new bucket of joint compound may look mixed, it may look dry, or it may have a little water on top. In any case, start mixing the compound with a mud masher or a drywall mixing paddle in a 1⁄2-in., low-speed (450-650 rpm) drill. You’ll soon notice that the compound has fluffed up and feels softer.

Step 2 Add a few ounces of water. You can use joint compound at the packaged consistency for filling corner bead and fastener heads, but you should add a few ounces of cool water and remix to make applying tape and second and third coats easier.