Here, no atmospheric moisture is needed. Usually an organotin
salt is used as catalyst, but it also limits the stability of the
resulting elastomer at high temperatures. Alcohol is released
as a by-product of the reaction, leading to a slight shrinkage
upon cure (0.5 to 1% linear shrinkage). Silicones with this cure
system are therefore not suitable for the fabrication of parts
with precise tolerances.