Paper tape is a popular option for finishing drywall seams.
Paper drywall tape is, like plywood and nails, a building supply that never becomes obsolete. Despite the ready availability of self-adhesive fiberglass mesh tape that is stronger and requires no undercoat of joint compound, drywall installers reach for paper as often as for the mesh, if not more often. Expense is one consideration, but paper tape is also easier to use and makes a satisfactorily secure joint under most circumstances when you install it correctly.
Drywall Tape and Joint Compound
Manufacturers design paper drywall tape to be used in conjunction with joint compound, usually called mud, which, like the core of drywall itself, is gypsum-based. The mud is at once the adhesive that holds the tape to the wall and the coating that hides it. Most applications call for non-setting mud that dries by evaporation, but setting-types, called hot mud by drywall professionals, are harder and more suitable when cracking or wall movement is likely to be a problem. The mud permeates the tape, which becomes hard as the mud dries to form a non-permeable and easily concealed covering.
Taping Flat Seams
Whether you use conventional or hot mud, you need to spread a coat along an entire seam to hold the tape. A smaller drywall knife, about 4 inches wide, is best for this. If you spread a layer about the same width as the blade, it will be slightly wider than the tape and ensure that the edges will be well-bonded. Some drywallers prefer to moisten the tape before laying it to help the adhesion. After laying the tape, scrape it flat with the knife. This removes excess mud from underneath that you can recycle for further use.
Taping Corners
Paper tape is suitable for covering inside drywall corners, but outside corners require something more durable, such as metal corner beading or bullnose, which can be metal or plastic. The technique for taping inside corners is similar to taping a flat joint except that you have to spread joint compound on two surfaces and fold the tape before applying it. Some drywallers scrape inside corners with a 90-degree-angle knife, but others simply use a conventional flat one. Because you nail or screw it on, metal corner beading doesn't require an undercoat of mud, but it usually requires several topcoats.
Finishing Taped Seams
Once the tape and first coat of mud have dried, which usually takes 8 to 12 hours if you're using non-setting mud, you hide the taped seams by applying two to three topcoats of mud. A thinner variety of mud, called topping compound, is available for this purpose, but you can also use the same type you used for taping. Apply each coat and scrape it flat with a progressively wider knife, using one that is 10 to 12 inches wide for the final coat. This feathers the edges gradually into the wall and, if done properly, completely hides the joint.
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