How to Mud the Third Coat for Drywall

A professional drywall expert will display their artistry on the third coat. There cannot be any grooves or streaks and the area must be truly smooth. A professional will take their drywall knife and scrape over the second coat to remove the ridges and other marks. It is important that the second coat be as smooth as possible.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

• 4-inch putty knife
• Joint compound
• 6-inch putty knife
• 8-inch putty knife
• 12-inch putty knife

1. Check the joints to see if they are dry from the second coat. Run your hand along the compound and feel for any large bumps.

2. Take the putty knife and hold the edge against the hump. Rock the knife on the hump.

3. Decide if you need to feather the joint. You will need to feather the joint if there are large humps in the compound.

4. Select a can of joint compound that has a wide enough mouth that you can use the mud right out of the can.

5. Determine if you want to thin out the mud. Some professionals like to thin out the mud for the first and final coats. It is a preference, not a rule.

6. Fetch a cup of water if you plan to thin out the mud and add one cup of water at a time. The goal is not make the mud so runny it won't stay on your putty knife. Thinning the mud weakens the compound.

7. Pick a wide putty knife no smaller than 8 inches in width for the screw or nail holes. Use a putty knife of at least 12 inches for the taped areas.

Tips & Warnings

• Sand only the final coat of mud.
• The mud dries quickly, so keep moving it in the container to keep it soft and pliable.
• A flashlight shining on the drywall compound will show you all the imperfections.
• Always tape vertical joints before you tape horizontal ones.
• Do not use fiberglass tape.