# How to choose an insulating material for a heated metal rod

I have a rod heater mounted in a brass rod and I need to coat the rod with a solid thermal insulator. I have the following options:

• PTFE
• Teflon
• Polyurethane foam

However, I doubt that the foam would be suitable when it comes to be in direct contact with the brass rod. How can I choose the right insulator for this application?

• This isn't a meaningful question without information on physical space available, on the temperatures the brass rod will reach, and the surrounding ambient temperatures, and the amount of heat loss acceptable. An answer could then tackle the specifics, while illustrating the generalities. Dec 17 '15 at 15:05

• PTFE Melts at 327$^o$C but the glass transition will be below that. It may work. Dec 17 '15 at 14:08