intumescent

This can take the form of intumescent paint, which swells when exposed to heat, or other insulating materials such as gypsum or concrete cladding.

The rough coating is a fireproofing substance known as intumescent epoxy.

But in between them is something called “intumescent goo” and what it does is react chemically to heat, forming a barrier that helps stop a fire from spreading to adjacent cells.

I do not advise trephining in the secondary glaucoma following intumescent cataract, for in such cases the semi-fluid lens bulges into and blocks the trephine hole.