Q: There are so many joint compounds and mud products these days. How do we know which to use for a typical drywall tape repair and skim coating scenario?
A: For patching I like either self-sticking fiberglass mesh or FibaFuse (fiberglass mat) drywall tape.
Pro Tip: Be sure to put a screw the base around the perimeter of the old drywall patch to solidify the area and avoid future cracks!
For making the initial skim coat strong, and also to speed up the drying time, I like to use setting type compounds (5-, 20- or 45-minute mud). Which one to use usually depends on how big the patch is.
Here is an idea of square foot coverages to help choose:
Small: 5-minute mud (1/2 a sheet of drywall max)
Medium: 20-minute mud (up to 1 sheet of drywall)
Large: 45-minute mud (more than 1 sheet of drywall)
When using fiberglass mesh tape in a repair, you should always use setting compound for the first coat, as most manufacturers will state in their instructions.
For the second skim coat, I like to use the setting compound so that a third coat can be applied more quickly. However, premixed joint compound is fine for this coat as well. Just note that it will have a longer drying time than the setting compound.
Lastly, for the third coat I always use a pre-mixed all-purpose joint compound. I slightly thin it with water to skim over all of the two previous coats of mud. Believe it or not, if you put a floor fan on that skim coat it will be dry in an hour or so.
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Then you are ready to final sand, prime and feather the patch. Sometimes it is necessary to put a full coat of paint on the wall or ceiling, if your feather-in coats don’t match and blend well enough. Answer: courtesy of Florida-based drywall pro Paul Peck of Peck Drywall/Painting and Drywall Tube: