If you're using epoxy resin in the final part, and if you don't plan to
use the mold too many times, then cover the foam mold with wide clear
packing tape. A roll costs very little, goes a long way, and the tape
releases wonderfully without wax (little cleanup required afterwards).
Polyester resin works with this also without affecting the tape, but
special care must be used to overlap the tape well as the resin may seep
beneath the tape and affect the glue and foam underneath.
This technique also works well for making fiberglass vessels, pipes and
the like, where you want to remove the mold destructively. Once the resin
has set, dissolve the foam (I typically use laquer thinner, outdoors -
laquer thinner has no/little effect on epoxy, which is what I've been
using), then pull the remaining tape out (the part must be designed so as
to allow a hand in to remove the tape). Again, take proper care to ensure
overlap of the tape so as to protect the part from the sticky laquer/foam
solution.
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Regards,
Rick
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Post by tonybroadHello from England - i'm looking for an inexpensive method of
sealing/preparing polystyrene (styrofoam) so that i can take a
fibreglass mould from it - i have no other material options other than
polystyrene, and epoxy resin is far too expensive
thanks in advance
tony