Getting rid of bubbles in mold

Getting rid of bubbles in mold

Post by Elda » Thu, 13 Jun 2002 04:19:23



I’m in the process of creating several molds that have to be
transparent. Having decided on a *** compound from Smooth-On that
meets the necessary criteria there is one other hurdle to overcome --
tiny air bubbles that seem to form while the mold material is curing.
These bubbles effectively render portions of the mold opaque after
curing. Posts seem to suggest that most of these bubbles are created
during the mixing process but this doesn’t seem to be the case
here unless they were microscopic after pouring and merely got larger
during curing. A Smooth-On rep suggested that it may have been too
much release agent, too much moisture in the master etc., etc., etc..
Whatever, I am investigating taking the vacuum chamber approach in
getting rid of these bubbles since it would seem that the possible
sources are many. Would placing the poured setup in a vacuum chamber
(20 – 25”) for the duration of the material’s  pot
life (30 minutes) be worth a try? I don’t see any advantage in
placing the mixed material in a vacuum chamber before pouring if the
entire poured setup can fit in the chamber. Perhaps I’m missing
something here.