Where I have a "cut" edge rather than a tapered side edge with the paper
wrapped around, I will take a carton knife and cut a 45 degree angle about
1/8 to 1/4 inch wide. This reduces the burr that often results from the
factory cut edge or from cutting and sawing drywall. This makes a smoother
job of taping and mudding on non-tapered edges.

"jim" wrote in message
...
Son - in - law (ex to be) decided to do this old guy a favor and
drywall the cottage mud room. Left the plastering / mud to be. Only
problem is that in several joins he did NOT butt the tapered edges
together. Thus there is no "groove" in which to fill with mud and
feather out for the smooth finish. Any way to remediate this other
than rip it out?