Let’s discuss why you need to choose tin or platinum when buying silicone for mold making. First you should know tin cure is also known as “condensation cure silicone” and platinum cure is also known as “addition cure silicone”. When you choose the wrong one it could mess-up your costly master model beyond repair. In one instance the silicone might not cure against the substrate material and remain sticky no matter what you do and in another, it doesn’t cure for days because you’re in an extreme dry climate giving you the impression all is lost when it probably is not. What does this mean to you? Read on and you’ll know how to choose before buying avoiding potential costly issues.
Tin cure silicone is almost foolproof. silicone stacker Usually a 10:1 mix ratio by weight. Once mixed it will cure easily against most master model making media (oil clay, plastic, wood, stone, etc.). To cure it takes condensation from the air and gives off a byproduct of alcohol or ethanol. Since there is evaporation in the form of alcohol there is shrinkage of the same amount, usually in the 0.3-0.4% range; acceptable for most applications. Tin cure is robust, high in tear strength and a great tool making rubber. Bronze Foundries and Sculptors love it for its ability to make molds of fine detail and for the security of knowing it will cure against their precious masterpiece. Others love it for being easy to use and for its great strength.
Some companies offer two catalysts:
Normal / Slow, usually a 60-90 minute work time and 12 hour+ cure / de-mold
Fast 15-20 minute work time 6-8 hour cure / de-mold
Some fast catalysts are not mix-able or compatible with the normal cure catalyst
Other companies offer three catalysts:
Normal / Slow, 60-90 minute work time and 12 hour+ cure / de-mold
- Quick 30-35 minute work time 4-6 hour cure / de-mold
- Fast 15-20 minute work time 6-8 hour cure / de-mold
All three catalysts can me mixed or blended together to create the cure speed desired