Drywall Compounds

Drywall compounds, commonly called "mud" in the trade, come in such an astonishing variety that it could easily confuse a beginner. Here's a quick rundown:

You'll sometimes see drywall joint compounds named for the function they perform. But excelling at that one purpose often means a compromise of other characteristics. For example, a taping compound is usually a setting-type that achieves high strength but is extremely difficult to sand. As a result, you'll want to make certain that subsequent coats will completely bury it.

Professionals know that compounds that are easy to sand, such as a topping compound, also have a texture that spreads more easily. But topping formulations, whether ready-mixed or setting type, lack the strength for taped joints. Save the topping compound for the final coat.

All-purpose compounds represent a compromise between strength and easy sanding. If you use one of these formulas, you'll sacrifice a bit of strength in the first coat and some ease of handling and smoothing in later coats.

Setting-type and ready-mixed joint compounds produce similar results but achieve them in different ways. A setting-type compound is a powder that you add to water. The addition of moisture begins an irreversible chemical reaction that causes the ingredients to harden. Ready-mixed joint compound hardens as the water in it evaporates.

If you can buy only one type of mud for your project, premixed all-purpose compound produces good results.For repairs, choose a nonshrinking surfacing compound or purchase drywall compound in a tube.