Giving drywall a smooth finish


November 20, 1993|By Karol V. Menzie and Randy Johnson

One of the nicest things about finishing drywall is anybody can do it. With a little practice, and a little patience, even a drywall rookie can end up with seamlessly smooth walls that just beg for a coat of paint to perfect them.

There are, of course, a few basic rules. The first one is, don't start finishing until you are through installing. That is, all the drywall must be in place, each piece snugged tight to its neighbors, with no cracks or gaps, and all outside corners neatly finished with corner bead.

The cleaner the surface and the cleaner the work area, the easier it will be to get finishes that are smooth, not gritty, and lump free. Think of it this way: Everything that's not absolutely flat will have to be sanded until it is. And the second rule of drywall finishing is: Minimize sanding wherever possible.

Even veteran rehabbers are continually startled by the amount of dust and debris the simplest job can kick up. It's not possible to eliminate it entirely, but careful attention to the process at all stages can make the dust problem manageable.

Joints in drywall are covered by laying down a thin coating of joint compound -- old-timers call it "mud" -- then embedding a strip of paper joint tape, then covering the tape with a second and third layer of compound.

Try to develop a rhythm, to work as smoothly and evenly as possible. It takes a little practice -- start in a closet, and polish your technique where it won't show so much before starting on the walls of a room. The more successful you are at keeping the compound thin and smooth, the less you will have to sand.

While you're working, it's important to keep the compound and your tools clean. At the end of the day, clean all your tools and dry them with a towel. If there are lumps in the compound, pick them out and throw them away. Keep a spare piece of plywood handy to scrape off dirty compound.

The compound itself comes premixed or dry (to mix yourself), in 1-gallon or 5-gallon buckets. The 5-gallon buckets have handles and, once empty, are reusable for so many things -- from carrying tools to using as scrub buckets or even step stools -- that they are worth the price of the compound. The premixed variety of compound is the best bet for novice drywall finishers, though you have to take extra care to make sure the remainder doesn't dry out between applications.

The broad, flat trowels used for finishing drywall are called knives. Having a good selection of knives is a big help in getting the compound smooth -- you'll need 4-, 6-, 10- and 12-inch widths.

Other useful tools are a spool to hold the roll of drywall tape on your belt, and a pan to hold a few knives-

full of compound. (Take out what you need and put the lid back on the bucket -- that will help keep the compound clean.) Start the process by taping the horizontal joints. Usually these are the joints where two beveled edges meet, so the tape will be recessed. Use a 4-inch or 6-inch taping knife to put down a thin layer of compound -- you want just enough to make the tape stick.

Measure out the tape you need to do a single joint in one piece. (Hint: Hold the tape against the wall with the knife and rip it back against the blade; it will tear smoothly.) Place the tape over the joint with your fingers, pressing it into the joint compound. Then go over the entire length of the joint with the knife, starting in the middle and dragging the knife out to each end. Keep the knife edge pressed flat against the wall and apply even pressure; the goal is to drive out virtually all the joint compound, leaving the tape tight against the surface, with no air bubbles. You may have to go over it a couple of times at first. Then scrape away all the excess joint compound and scrape it back into the pan.

Hint: To imbed the tape, hold the knife with the blade flat against the wall and your hand close to the wall surface, so there's a narrow angle between the knife and the wall. To remove excess compound, keep the blade flat but increase the angle by placing your hand a few inches out from the wall.

Once the horizontal joints are done, do the vertical joints. Then do the corners. You can do both sides of an outside corner at once, but if you're not an expert, you should do just one side of the inside corners. Because of the corner beads, outside corners take a lot of joint compound to fill. Start with a 6-inch knife and apply as much compound as it takes to leave it flush.

Let the joint compound dry. If you've worked fairly slowly, some of the first joints may be dry when you finish the last one; but the outside corners will probably dry over night.

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