I just ordered a two DVD video course on all the methods of making rubber molds for injection wax duplication. There are two major options. One is a heat vulcanization process and the other is room temperature vulcanization (RTV).
At this point I do not know which method I would prefer. There is one factor that is important to consider and that is the heat and pressure involved. The hot method has a lot of both. Fragile models will not survive the hot vulcanization and being clamped under pressure. That includes using carved wax as the master model.
I am expecting the video training will make the options much clearer for me in deciding what method I will employ, at least coming out of the gate for my first attempts.
Once the mold has cured with either process, the master cut out and wax injection are exactly the same. I believe the life of the rubber molds in either process are similar, but then I expect the video to make that point clear.
I am not real excited about the RTV process because of all the chemicals involved. I am willing to use the process as I have done so many times already. The fact is that it just gets everywhere and has to be exactly measured, weighed, evacuated, poured carefully and is therefore less “friendly” than stacking slabs of uncured rubber together and squeezing in a heated press.
On the other hand, the heat process does need the pressure and the heat source which requires a financial investment (probably lifetime) in the vulcanizing press.
Ha! So I will see from the training where I will go.
Here are some (example) pictures of the equipment required. This may not be what I end up with, but it shows it is a rather significant addition to my studio equipment. I don't buy junk, but I don't go for the high end either. I do have to have the proper tools.
The wax from the rubber mold is then used in the lost wax casting process. Many wax duplicates can be made from the rubber mold rather than carving a new wax master every time.
I have just ordered the exact equipment shown above. The brand names may be a bit different but the hardware is as shown. I am or will be using the hot vulcanization process.
The demand for duplicate castings has convinced me now is the time to take this next step.