Hello everybody,
i`m new to casting & moldmaking and i have a question:

i made myself a RTV mold and i want to cast Polyurethanic resin into it.
how many times can i cast into this mold before it becomes useless (the detail vanishes)?
will my mold last longer if i use a demolding spray?

searching on the web i found numbers between 25 and 100 castings in the same mold until it cannot be used anymore.
thanks for your time.
andi

Yes, your mold should last longer if you use a mold release. And yes your likely to get about 100 castings although there are a lot of factors that come into play. The casting material will make a diffence. Water based casting materials are not likely to cause as much damage as resins will. If the casting has dramatic undercuts it's likely to have a significantly shorter life span. Silicones are superior than Urethane RTVs in that they don't require a mold release and are non toxic. Urethanes tend to be cheaper though.

It really does depend on what it is. Casting with a Urethane plastic (resin) is a lot harder on the mold. The thing to remember is silicone rtvs are designed to take the higher exothermic heats of resins and plastics where Urethane rtvs are not and could distort and break down faster under heat. Urethanes also need a release agent. They're great for concretes, plasters, wax.... but not really the resins.

~ Niki

we are interested in buying moulds for artificial stone.