IF you want something similar go to an autoparts store and look at muffler
tape. There is a brand just as you describe , cloth tape with plaster of
paris, that you soak in water and wrap around the exhust pipe to seal leaks

wrote in message
ps.com...
My HVAC unit is up in the attic. It works fine - I just cleaned the
coils - but at each end, where the unit connects to the main intake and
output ducts, it's wrapped with this plastery-looking material. It
looks like strips of cloth that have been soaked in Plaster of Paris,
or maybe wheat paste. Some of it has cracked and is leaking air, so I
want to replace or add another layer to it. Can somebody tell me what
this stuff is? Hopefully it's something I can buy cheaply at Home
Depot.

Thanks,
Ron M.