Drywall taping and finishing isn't a difficult job, but it can be a messy one, and a mess can produce substandard results. Pros often use a pair of handy tools to help them do a neater job while saving time. The first is a banjo, which is a machine that automatically coats tape with joint compound and feeds it onto joints, and the second is a finishing box, which is useful for recoating taped joints.
After hanging the drywall, the first tool that the professional finisher uses is the banjo. It has a compartment to hold paper drywall tape, and the tape feeds through a second compartment that holds mud. If the mud has been thinned to the proper consistency, the tape emerges from the tool evenly coated on both sides and ready to lay on the wall. A banjo saves time because it deposits the tape flat on the wall and eliminates the need for hand scraping. It also reduces the possibility of bubbles or separation because of insufficient mud underneath the tape.
Professionals produce flat seams by coating and recoating taped seams with mud and scraping them flat, each time using a wider drywall knife. A drywall box combines the process of applying mud and scraping it into a single motion. Because the box is on a handle, the worker can stand far from the wall, out of the range of falling mud, and finish a seam more quickly. Like drywall knives, finishing boxes come in various widths, and you need at least two different boxes -- preferably three -- to properly finish a joint.
Mixing and Filling
You can use all-purpose premixed joint compound in a banjo or a box, or you can mix the powdered variety. Either way, it needs to be a little thinner than the mud you use for hand finishing so the machines can spread it, but it shouldn't be pourable. Filling either a banjo or a box is easier if you have an electric pump, which automatically transfers mud out of the 5-gallon bucket in which you mix it. It's a good idea to test the mud consistency by doing a sample seam before you completely fill either tool.
Taping and Finishing
You use a banjo by holding the tape against one end of the seam and drawing the tool in a straight line, pressing down on the tape as you go. When you reach the end of the seam, the machine automatically cuts the tape. The principle behind a finishing box is similar. You hold the box at one end of a seam and draw it against the wall toward the other end. It lays a flat coat of mud that doesn't need scraping. Both tools clean easily with water at the end of every session.
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