Don't know about the shelf life of a mold made with LiquaCast, but
the RTV molds I've seen usually outlive the vulcanized molds.
Hi David, the following info on LiquaCast RTV molds was copied off
of Castaldo’s website
"Do not allow molds of one type of rubber to remain in contact with
those o f other rubbers as migration of oils or plasticizers from one
to another can cause swelling, shrinkage, or distortion.
If the mold is left in a distorted shape for any length of time it
can take a permanent set and may never recover to its original shape.
Cured LiquaCastAE molds will slowly soften with age due to ambient
moisture in the air. Proper mixing of components in the correct mix
ratio contribute s to longer mold life. Storage of molds in a dark,
cool, dry area will prolon g life, as will reducing contact with moist
air by enclosing stored molds in tightly closed plastic bags. Wax or
metal patterns should be stored in the molds to maintain their shape.
With proper care, molds should not soften appreciably for 2 - 4
It’s important to heed these storage directions for LiquaCast molds!
If stored with gum rubber molds you can end up with unusable
LiquaCast molds and a huge gooey mess.
I use urethane molds (such as LiquaCast) when I want an affordable
mold of a wax model. I almost always take a second mold (vulcanized
rubber or silicon e mold) off the finished cast master. I don’t count
on the urethane mold bein g usable in 4 years. They get soft and gummy
over time. For a mold that will last me years longer I choose gum
rubber or silicone. HTH Kate Wolf in Portland, Maine - check out our
fall workshops! http://www.katewolfdesigns.com