How to use a banjo
Taping drywall isn't for everyone. It takes patience and a fair amount of skill to do a good job. But if you're like me and enjoy the challenge, here's a tool you've gotta try out. It's called a banjo and it makes short work of covering drywall seams with paper tape. But speed isn't the only advantage a banjo offers. It practically eliminates the common problem of loose or bubbling tape that plagues many beginning tapers.
In this article, we'll show you how to use a banjo to apply the first coat of paper tape to drywall seams. A banjo like the one we're using costs $75 to $100, a big investment for the occasional taping job. Fortunately, most full-service rental stores and some home centers rent banjos for about $10 per day— plenty of time to get a coat of tape on one or two rooms.
Thinned mud is the key to success
You'll find ready-mixed joint compound (called “mud” in drywall taping lingo) in plastic buckets or boxes at home centers, lumberyards and drywall suppliers. Buy all-purpose lightweight joint compound (one type is USG's Plus-3) and use it for embedding the tape as well as covering the tape with the second and third coats. You'll have to thin the mud with water, up to about 4 cups per pail, before you pour it into the banjo. If you're only taping one or two rooms, transfer a few gallons of joint compound to another bucket. Then you'll still be able to use the remaining thicker mud for troweling on the second coat. First mix the joint compound with either a potato masher– type mixer like we're using (Photo 1) or a mixing paddle and heavy-duty 1/2-in. electric drill (mashers or paddles are available for about $11 at home centers and drywall suppliers). Then mix in water a little at a time until the joint compound drips in large blobs from the mixer (Photo 1).
The true test of proper mud consistency is how well it works in the banjo. Too thick and you'll struggle to pull out the tape. Too thin and the mud will leak from every nook and cranny. When you get it right, the tape will pull out smoothly, be evenly coated and flatten easily with your taping knife (Photo 4).
Adjust the banjo to let out just enough mud
Load the banjo with paper tape and thinned joint compound (Photos 2 and 3). Then with the nose of the banjo angled toward the floor, pull out a few feet of tape and inspect the back. A properly adjusted banjo should leave an even 1/8-in. thick layer of joint compound. On most banjos, the width of the slot where the tape comes out is adjustable by either turning a thumbscrew or loosening Wing-Nuts and sliding the tape cutter up or down Test the setup by applying strips of tape to a scrap of drywall and flattening them with your taping knife. If very little joint compound oozes out from under the tape as you embed it, widen the gap to deposit more mud on the back of the tape. If there's so much joint compound that it's difficult to embed the tape and a large amount of mud piles up under your knife, reduce the size of the opening.
A layer of mud on the top and bottom of the tape ensures success
Photos 4 – 8 show how to apply the tape to seams. To ensure trouble-free results, prefill the gaps between sheets of drywall with a setting-type joint compound and allow it to harden. Be careful to wipe off all excess compound flush to the drywall as you apply it, and scrape off any dried lumps with your taping knife before you start taping. As you pull the tape from the banjo, the topside may be dry or have very little joint compound. This isn't a problem as long as you trowel a thin layer of joint compound over the tape before you embed it to lubricate your knife. If friction from your knife is leaving the tape fuzzy or causing it to buckle up into little ridges, you'll know you need to trowel on a thin layer of mud before you trowel the tape flat. Transfer the mud that oozes out from under the tape back onto the surface of the tape as you go.
As the mud in the banjo runs low, it will no longer cover the bottom of the tape and the tape will be very easy to pull out. These are clues to refill the banjo. Open the cover and reposition the tape (Photo 2) before you refill the compartment. Joint compound often thickens as it sits. You may have to mix in a little more water.
Follow this sequence for the best results
The pros we talked to suggested applying tape in this order: (1) the vertical seams, (2) the horizontal seams and (3) the inside corners. It's OK to overlap the tape where one seam meets another. Divide long horizontal wall seams or seams that run across an entire ceiling into smaller sections by cutting the tape at an intersection with another seam (it's difficult to embed a section much over 10 ft. long). Always start at the center of each section and work toward the ends when you're embedding the tape (Photo 6). It's OK to tape a number of seams before returning to embed the tape as long as the joint compound doesn't start to dry out. Working with a partner who follows closely behind to embed the tape is a good way to speed up the job.
Keep the tools clean to avoid lumps
Taping is a messy job. It's a good idea to keep the banjo, mud pan and taping knife free of dried joint compound. I like to keep a 5-gallon pail of warm water and a sponge handy to clean my hands and wipe off the tools. Otherwise, little chunks of dried mud will cause all kinds of trouble as they get stuck under the tape or in the joint compound. When you're through for the day, scrape excess mud into a garbage bag and scrub the banjo and tools with a stiff-bristle brush to remove joint compound before it hardens.