I recently did 12 panels all on the same mold, should be able to do that and
more.

Why are you mistified by the fiberglass? I didn't say not boat fiberglass,
I said "1/32 chopped/milled fiber"

US Gypsum only rates Hydroperm to 1000 deg. by adding a "binder" you can go
much higher, I have taken molds to 1415, but remember, the temps I quote are
on my digital pyrometer, (which I believe to be accurate.)

If you read any of the molding/casting books, for glass or metal, there are
refractory mold materials and binders and while not the same, they work
together to accomplish what we need to do the job.
Just be really careful and not get your ratio of binder to plaster too high.

And as long as you are concerned with mold strength, how many firings, don't
make your mold too "wet", make it a drier mold and they last longer, my
experience.

Good luck, need help, write again, have no trepidations, mix it up and dig
in!!


"Liam Striker" wrote in message
y.com...
questions...
how may firings do you get out of one of your hydroperm-fiberglass molds.
and
I'm mistified by the fiberglass. Not boat fiberglass? I didn't know
there
was a difference. Where should I look for the right stuff?

Thanks
Liam