This should be a pretty straight forward question but I can't seem to find the type of material that is used..

So I am making my own heating coil out of Nickel Chromium wire. I plan on using two bolts in a frame that hold the entire thing together. Obviously the bolts themselves are conductive so my plan is to wrap the bolts in the "heat resistant cardboard" that I see inside of hair dryers and other heating devices that use the same wire. Does anyone know which type of material this is, as I am sure normal cardboard would simply ignite...

  • $\begingroup$ Are you thinking of Mica? en.wikipedia.org/wiki/Mica#Built-up_mica $\endgroup$ Apr 12, 2018 at 14:47
  • $\begingroup$ @JonathanRSwift That might be correct.... IF you had a heating element in contact with Mica you would have no problems wouldn't you? Also I was thinking cork might work well too.. $\endgroup$
    – Eric F
    Apr 12, 2018 at 14:58
  • $\begingroup$ Cork - really ? Is that considered non-combustible? $\endgroup$
    – Solar Mike
    Apr 12, 2018 at 15:20
  • $\begingroup$ What's the maximum temperature of your NiChrome? What other safety features does your system have (e.g. thermal fuse?) to prevent rising above this? Cork starts to degrade significantly above 200C link.springer.com/article/10.1007%2FBF00200161 $\endgroup$ Apr 12, 2018 at 16:54
  • $\begingroup$ Flame resistant and cardboard do not belong in the same sentence. $\endgroup$ Apr 13, 2018 at 19:05

1 Answer 1


The "Heat resistant cardboard" that you are describing is likely 'Built-up Mica'.

Clearly this is not "cardboard" (as specified in the original question - now edited to say "material"!), since it is not paper-based, but, I hope it can be used for your application.


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