Yes, that is adhesive and moisture barrier, the goop, that is.
I find it much easier to use a very large pair of shop scissors to cut the
batts in two stages, first on the paper side, then the pink fuzzy side, and
it comes apart. Also, much less buildup of tar vs a utility knife blade.

"Larry Bud" wrote in message
oups.com...
Putting up insulation for the first time in my life, and noticed that
my razors get black crap all over them in short order.

Is the fiberglass doing that, or is it some glue in the kraft paper?