Once you have installed the drywall on a new wall, you need to apply drywall tape to the joints between the pieces of drywall before you paint or paper.
Mix or Thin Joint Compound
If you are using ready-made joint compound, then you will want to thin it slightly before attempting to use it for taping seams. The texture of the mixture should be similar to pudding.
If you are using a joint compound mix, then mix the drywall compound according to the instructions on the back of the package. Again, attempt to create a pudding-like texture in the compound.
For ease of use, mix the mud in a bucket and then place it in the pan as you need it to spread on the drywall seams.
Plan Your Taping
You should first tape the butt joints – places where ends of drywall sheets butt together. The next seams you address should be the recessed seams where the sides of the drywall sheets meet. After the recessed seams, address any detail seams, such as those found around pipes, outlet boxes, holes, etc. Dents and dings should be filled in last.
Use the 4 or 6 inch knife to spread a layer of drywall mud along the length of the drywall seam. Spread a seam of at least 4 inches and up to 6 inches of mud. You’ll need mud under all parts of the tape.
Measure the seam and cut a strip of drywall tape to fit. Then dip the 4-inch drywall knife in water and place the tape so that the center of it runs down the drywall seam. Place the tape so that the pointed side of the fold goes against the wall and into the seam.
Starting from the center of the seam, use an 8-inch knife at a 45 degree angle to swipe toward the end of the seam. Then start again in the center and swipe toward the other end. Make sure mud oozes out on both sides of the tape. If it doesn’t, you’ll need to lift the tape carefully and add more compound. Scrape away any excess mud. Smooth to ensure that there are no air bubbles.
Let the mud and tape dry for 24 hours.
Clean Up the Seam
After 24 hours, use the drywall knife to smooth off any rough edges of the mud.
Apply Second Layer of Mud
Mix or thin a new batch of joint compound. Using a 10 inch knife, add another coat of joint compound over the drywall tape. Apply a second coat of mud, about six inches wide, that covers the entire tape. This layer should be thin so that the tape shows through the mud. Let the mud dry 24 hours.
Clean Up Seam
Clean up the seam by scraping off any protrusions or rough spots after adding the second coat.
Add More Layers
To completely finish the taping job for drywall, use a 10 inch drywall knife and apply a light third coat of drywall mud. Spread the even wider for the third and subsequent coats—approximately 8 to 10 inches wide.
Let the mud dry 24 hours, then add an additional coat if needed for smoothing the entire area.
Clean up Seam and Sand
Clean any remaining mud. Lightly sand the edges of the tape seam using 200 grit sandpaper to smooth it into a workable surface.
Clean and Prime
Before you finish the wall with paint or paper, you will want to smooth the all the rough seams and create a smooth surface.
Taping drywall is a skill that you can learn with a little practice. The satisfaction and cost savings you’ll enjoy make it well worth your time.