Operation instructions for making a mold by RTV silicone rubber

Correct mixing ratio

Component A is silicone rubber, and component B is curing agent or vulcanizing agent. Usually the mixing ratio will be 2-3%, e.g. to 100g silicone rubber should be added 2g catalyst and then mix them thoroughly. (Note: the weight of the silicone and catalyst must be weighed accurately).

Preparation of the original molds

Because RTV silicone reproduces the surface texture of the original model exactly, the surface of the original to be molded must be finished: all faults must be removed, and it must be sanded or polished to the desired smoothness. If a smooth finish on the final casting is desired, the original must be polished. For a matte finish, polishing is not necessary.
Vacuum deairing

Vacuum deairing is a method of removing entrained air bubbles from the mixed silicone and catalyst. Air can be mixed in during the mixing of the silicone and hardener and, without Vacuum deairing, the bubbles may not be released from the mixture. If a large number of bubbles are present internally in the mold then the mold will have a lower tensile strength which, in turn, affects the reproduction times.