Every house, at some point in time, needs a repair made to a drywall or plaster wall or ceiling. To save money, you might have tried this -- and failed. It's tough to get professional results, but it is possible. You just have to know a few secrets. You also need to be patient and practice.
You can watch a short video showing how to finish drywall by going here: go.askthebuilder.com/finishdrywall.
You'll need a 5-inch flexible drywall taping knife, a 10-inch flexible drywall broadknife, a mud pan, pre-mixed drywall all-purpose compound, paper drywall tape and a drywall sanding pad.
Mix up the joint compound so it's the right consistency. The compound from the factory is always too stiff. Add water in small amounts, only mixing up the top layer in the new bucket. The consistency of the mud should resemble warm cake icing that is very easy to spread.
Apply a layer of the compound over a seam or crack that needs to be repaired. The layer of compound should be 1/8 inch thick and uniformly smooth. Embed a piece of the paper tape into the compound and use the 5-inch knife to pull out excess compound from under the tape. You want to remove only half the compound you originally applied, making sure there is at least a 1/16-inch layer of compound under the tape. If you remove too much compound from under the tape, you'll get blisters in the tape when you apply the second coat. Allow this compound to dry for a day or two.
The second coat of compound is the hardest to apply. It requires a deft hand and great hand-eye coordination. Use the 10-inch knife to apply a layer of compound over the entire taped seam with the compound extending at least 2 inches on either side of the edge of the paper tape. The compound should be about 1/8 inch thick over the paper.
Holding the knife at an angle and applying pressure so one tip of it is touching the drywall where there is no compound, pull the knife at an angle across the compound, much like a snowplow plows snow. The other tip of the knife should be up in the air so it's creating a ridge of compound over the center of the paper tape. The thickness of the compound above the center of the paper tape should be just over 1/8 inch. The creamy consistency will allow you to feather the edge of the compound to nothing below and above the taped seam.
Step two will produce an ugly, uneven ridge of compound over the center of the paper tape. Don't worry about this. When the second coat dries in a day or two, you'll lightly sand off this ridge before applying the final coat.
When the second coat of compound is completely dry, sand off the center imperfection on top of the now-hidden tape. Brush off any dust. Use the 10-inch knife to apply the third, and final, coat of compound. Apply a 1 / 16-inch layer of compound over the entire area where you've previously applied the compound. Hold the knife at a slight angle and pull it across the seam, removing almost all the compound you just applied. This coat will fill in any minor imperfections.
The third coat will dry rapidly if the humidity is low. You can now sand the seam and inspect it for imperfections. Repeat steps seven and eight, if needed, to get a smooth surface on all seams.
Summary: It requires lots of practice to get professional results. The key is making sure the joint compound is the correct consistency. If it's too thin, it will fail. If it's too thick, you'll fight it every step of the way. The biggest mistake you can make is leaving too much compound on top of a seam, requiring lots of sanding. It's easy to add more compound. It's hard to sand it off.
DEGREE OF DIFFICULTY: Five hammers out of five
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