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Friday, October 1, 2010

Silicone rubber for resin molds
Silicone rubber is the material of choice for most resin molds. It has a fairly inert nature which endows it with good release properties, good chemical resistance, and high temperature resistance.
It comes in two formulations popular for mold-making: tin-cure (condensation) silicone and platinum cure (addition) silicone. Both are composed of two component materials which must be thoroughly mixed and vulcanize (cures) at room temperature (RTV) to become flexible, high tear-strength rubber suitable for casting polyurethane, epoxy and polyester resins with easy release properties.
Tin cure silicone can be poured into molds or made brushable by mixing in an additive. Even though it has a shorter shelf life than platinum cure (addition) silicon and tends to shrink somewhat, it is less expensive and does well for most resin molds.
Platinum cure silicone rubber, also known as addition cure silicone, is known for its extremely low shrinkage. A word of caution is necessary, though:  these rubbers are chemically sensitive to latex, sulfur, and certain other materials. Platinum cure silicones are also used to cast prosthetics for special effects makeup and medical purposes, and for making food-compliant molds.
When using silicone rubber to fashion a resin mold, plan and prepare your process ahead of time—reading all of the manufacturer’s instructions to make sure that you have enough time to mix the two components thoroughly and in the correct ratios and to form the mold before it begins to cure (usually in 1-1/2 to 2 hours).
ResinObsession stocks the following types of liquid room temperature vulcanizing (RTV) silicone rubber:
·         Alumilite High Strength 3 flexible mold-making Silicone Rubber;
·         Alumilite High Strength 2 flexible mold-making Silicone Rubber; and
·         Alumilite Quickset Silicone Rubber;
as well as two FDA food compliant silicone putty kits:
·         Alumilite Amazing Silicone Putty Kit and
·         Castin'Craft EasyMold Silicone Putty Kit
If you have any questions about our silicone rubber products or how to use them, Cindy- cindy@resinobsession.com , the ResinLady will be happy to answer them.
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