At the very most, twice the weight of the glass to be applied.
Glass products weight is measured in ounces per square yard (9 square feet).
Epoxy weighs roughly 10 lbs. per gallon.

"Clark" wrote in message
.. .
How much epoxy will it take to put glass on a four by eight sheet of
plywood
? just enough for water proofing and to prevent the plywood from checking.
I
have never fiberglassed anything before.