Drywall Finishing & Tape Bubbles

Causes for Tape Bubbles

• To finish a drywall installation, you must seal the seams between drywall panels with alternating layers of drywall compound, also called mud, and paper tape that bonds to the compound and creates a waterproof barrier. If bubbles form in the tape, they will show through whatever decorating or painting you do on the drywall. These bubbles can be caused by tears or loosened areas in the paper face of the drywall itself, or by incorrect flattening of the tape and mud.

Tears in Paper

• Damage to the drywall paper face will cause uneven application and staggered drying times, which will result in bubbles in the tape. Whenever you notice any damage areas of the drywall larger than 1/8 inch long or wide, you must repair them to avoid future problems. Cut away loose and damaged pieces with a sharp utility knife to create a smooth surface. Once the area is flat, prime it with a sealing solvent-based primer designed to prevent the mud from seeping into the surface and causing damage. These sealants generally come in spray cans, and are available from hardware and home improvement stores.

Flattening Technique

• The flatness of the tape starts with the consistency of the drywall compound. When mixing the mud, continue to stir until the consistency is creamy and smooth; it should be like thick, creamy peanut butter, so that it can be smoothed into place easily off of the end of your putty knife but will not drip. As soon as you apply a single thin coat of mud to the joint, line up a piece of paper tape centered over the seam and smooth it into place with a clean putty knife. Run the knife in one direction over the entire length of the tape, then start back at the beginning and run it through again. This will imbed the tape firmly into the mud for a better hold.

Removing Bubbles

• If your finished drywall is afflicted by tape bubbles despite your best preparation efforts, the last thing you want to do is try to cover the damage with a thick layer of mud and more tape above it. The bubble will only get larger and will show through all layers of mud and tape you apply over the troubled area. Instead, trim out the bubbles from the tape with a sharp utility knife. This creates a flat area over which you can apply another layer of tape and mud without the pressure of the bubble pushing outwards and causing further distortion.