I think when you are using an insulating material of any sort. One needs to be aware of what exactly you are insulating against.
One particular instance is 'Fire resistant paint'
Which when painted on the surface of plywood, stops it from catching fire even under the direct flame of a blow (kerosene?) torch.
Manufactures keep their formulations secret. But
most rely upon the ability of the paint to expand and form thousands of stiff carbonised bubbles, that keep the flames from catching the wood on fire.

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"You will never find a real Human being - Even in a mirror." ....Mike Kremer.