"I am replacing the skylight on Mellow Yellow. The replacement Volks Cafe
> skylight directions say to "add fiber gum or suitable caulking compound"

Dear Rocket Man..........owner, Eclectic Banana ;>)

I used black caulking, silicone, of the slightly "adhesive" variety. Working
marvelously. Was in the San Rafael Swell recently and this new job endured
about 8 hours of rain no-problemo. This particular stuff never gets hard,
but does get and stay firm. Slightly rubbery when you push your fingernail
into it, after it has dried. It's very easy to wipe the extra off the
bracket/joint before it dries so it leaves a very clean, tidy looking job
and provides a water tight seal.

bob