POLYURETHANE RESINS, SILICON RUBBERS
The creation of prototypes with silicone molds is a micro-production technique known as “soft tooling” since the mold is made of soft material.
This technique is essentially based on making a silicone mold starting from a “master” object.
When the silicone hardens around the master, it makes it possible to remove the latter, which leaves a hollow imprint, essentially creating a mold that can be filled with casting resins. The most commonly used casting resins are two-component polyurethanes that are formulated to resemble the most common production techniques, which can be either rigid plastics (opaque or transparent), or silicone rubbers.
The polymer flows are carried out in a vacuum chamber which serves to eliminate bubbles inclusions.
Thanks to the elasticity of the matrix, to silicone molds is ideal for making those complex figures, they are details and small undercuts that are “solved” by exploiting the elasticity of the silicone matrix the silicone mold. Because of this aspect of mechanical stress as well as chemical aggression, a silicone mold has a useful life usually not exceeding 20-30 extractions (depending on the complexity of the figure and the aggressiveness of the resin). The resins for silicone can be pre-pigmented giving life to objects already colored at will.