Shrinkage can be caused by a couple of things: 1. The type of silicone: Tin curing systems such as the High Strength 2/3 and Quickset will have minimal shrinkage from .25-.48%. Platinum-based silicones such as our Plat55 will have zero shrinkage. 2. The casting resin: The majority of Alumilite casting resins have minimal shrinkage. Our filled systems have close to no shrinkage. You can add fillers such as micro-ballons to resins such as AlumiRes or Regular to reduce or shrinkage, but it will thicken the resin. Most users find shrinkage is very minimal and that it does not affect their castings. Users needing high accuracy will use a platinum silicone and in some instances will add a filler to their casting resin.