This is only peripherally an electrical engineering question, but there are no other engineering forums on stack, so forgive me.
I am designing a homebrew device to melt low-temperature metals (like tin). I have a coil of heating wire. I am going to use an Arduino and a relay to turn the power on and off, and I have a thermocouple and a temperature sensor for thermostat control. The electrical side seems fairly simple.
The issue is that this wire is uncoated, as are all the others I can find. Since I want to wrap it around a metal container to heat it, I need a thin layer of insulation to prevent shorting the wire, while maintaining the best heat conductivity possible.
I found some ceramic insulators, but I'm not thrilled:
For one thing, I would need a lot of those. They are thicker, and have an air gap inside. Ideally, each insulator should be as small and thin as possible. A coated heating wire would be ideal. A coating would be great. I would like to wind the heater coil around a metal cylinder, possibly a can. I would love to coat the can with thin layer of clay, but I'm fairly sure thermal shock will rip it apart after one or two heating cycles. I would like the insulator to be able to tolerate at least 600°F, possibly 800°F. The can should be good until at least 1200°F from what we've seen so far putting them in hot wood fires.
I'm also interested in anyone's solution for regulating heat at the top and bottom as well. I was planning on a double-walled cylinder, with a bigger (insulated) outer cylinder, but I should probably heat the bottom as well. For the top, all I could think of was creating some kind of double-walled glass cover, but it would have to be able to take a lot of thermal stress, maybe the inside layer (or both layers) pyrex?
Ideas? Suggestions for parts/materials?