Lightweight “all-purpose” drywall compound and “easy-sand” 45-minute setting drywall compound are the two types novices should choose when planning on completing a drywall finishing project.
So many choices! Start by buying a bag of 45- minute setting drywall compound; you’ll find it in 30-lb. bags (and sometimes smaller boxes), with names like Durabond or Easy Sand 45 and it comes as a powder that you mix with water as you need it. It hardens quickly (surprise!, in 45 minutes), shrinks very little and dries hard as a rock. This makes it ideal for filling oversize cutouts around electrical boxes, nail and screw dimples and cracks in areas where drywall sheets don’t butt tightly. Since it dries quickly, you can move on to the “real” taping without waiting.
Buy an “easy-sand” variety; the standard stuff dries so hard you can spend hours sanding ridges left behind by your trowel. Always clean your tools off when finished unless you want to spend the extra cleaning hard drywall compound from your tools.
For embedding the tape and the subsequent layers, buy lightweight, all-purpose joint compound in the familiar 5-gallon bucket. This drying compound hardens through evaporation—which means waiting up to 24 hours between coats. Apply it full strength across the joints and at corners for bedding the tape. Then use it full strength or slightly thinned for the top layers. Try to avoid ridges and bumps. But if you get them, don’t worry; the lightweight compound sands easily. It also scratches easily, so get a coat of primer on it as soon as you can. It’s worth the extra buck per 5 gallons you’ll pay for it. A 5-gallon bucket will finish about 450 sq. ft. of drywall, the equivalent of fifteen 4×8 sheets.
What’s all the other stuff? Topping compounds are thinner and contain less adhesive than all-purpose compounds. This makes them easy to feather and sand and thus ideal for the final coat or coats. The five- and 20- minute setting compounds are used by for filling gaps, bedding tape, sometimes even for topcoats, but you need to be quick. If you’re a rookie, stay clear of these; they’ll harden before you know it.