The mold is done from the master, it is the negative of the master. This mold once it will be finished will be used to inject the wax that will be used for the casting.
Differents materials that exist to make this mold but there is two big families:
This materials provide a better definition but the lifespan is short.
These materials have a long lifespan but the definition is less
Depending on the need we have to choose the best to use. for example with the new semi automated wax injecting system all the rubbers cannot be used and it is even better to use silicon
Here is the different step to make a mold :
First covering the master with the rubber
Vulcanize the rubber
Cutting the mold