VULCANIZER


This 2 part mold was made with my homemade vulcanizer, at ˜325°F. Indexing was done with jewelry nailheads. I sculpted the figurine using Super Sculpey™, over a wire paperclip armature. The mold frame was constructed from one-inch-square steel tubing. The silicone used was an excellent, pliable, high temp product from Millennium Rubber Co, Merrimack, NH.
VULCANIZED versus RTV SILICONE RUBBER

Above are 2 raw pewter castings, unfinished, right out of the mold. The man with the shovel was cast in a vulcanized silicone rubber mold. The eagle dancer was cast in a high temperature RTV silicone rubber mold. (RTV stands for Room Temperature Vulcanizing). You can see quite a difference here. The vulcanized silicone rubber mold was held together with an ordinary elastic band while the molten zinc was poured in. The RTV silicone rubber mold was held together with a pair of metal clamping plates. The RTV silicone rubber mold yielded a casting with lots of flashing and a poor surface finish. Also, vulcanized silicone rubbers last longer and can withstand higher temperatures than RTV rubbers. You can cast zinc , not just pewter, in vulcanized rubber molds.

This mold was made in my homemade vulcanizer using two brands of silicone, and a shaft collar as a mold frame. The homemade vulcanizer plans include methods for constructing very low cost mold frames.	This switchplate was cast in scrap zinc using my homemade spincaster. The mold was made with my homemade vulcanizer. The zinc was melted using my homemade torch. The cast iron pot I used to melt the zinc was lined with homemade firebrick.

If you are planning to build a vulcanizer, or already have one, you may be interested in the free workbench thermocouple plans. On my vulcanizer, I use the simple method shown in the vulcanizer plans to control temperature, instead of a thermocouple. I have found the temperature control to be very adequate for all the brands of natural and synthetic rubber I have used. I mention this only because I have seen thermocouples used on commercially-made vulcanizers.