The Unique Expanding Foam works and acts very similar to the expanding foam "Great Stuff" available at home improvement stores.  The difference is that after curing for 12 hours, Great Stuff as well as SILICONE is flammable and emits toxic gas so noxious that a few deep breaths of it could be bad- very bad.  This is a serious error made by many racers and restorers, the placement of flammable and noxious seals in the firewalls.  Great Stuff and Silicone have their place in the home and shop.  They do not belong in the firewall of a vehicle whether it is a full blown race car or restoration project.  There are products marketed on the internet for automotive firewalls that are made of plastic or rubber - all fuel for an engine fire.

Unique Expanding Fire Stop Foam is designed to seal small cracks, seams and openings in a commercial buildings fire rated walls.  It will swell approximately seven times the size of the nozzle.  Try to get equal amounts in the opening of the automotive firewall so the foam will expand equally on both sides.  After cure time you can use a sharp razor to trim the material back.  It can be painted and no one will know it is fire stopped unless there is a fire.  Works well in conjunction with the Sponges and Firestopper Sleeves.

KoolMat is a space age material used in thousands of Commercial, Industrial and Automotive applications. KoolMat is a composite material of silicone cured to the surface and weave of a high temperature fiberglass substrate. Weighing .72 per sq. foot and a thickness of .070. Because the silicone attaches itself to the textile, there is no separation, and no flow of air or liquids through KoolMat. The silicone offers a great resistance to abrasion, radiant heat, gasses and oils. No matter what temperatures. It is also an excellent sound deadening device. KoolMat is flexible and can be die cut to any shape or size and still perform like no other barrier. KoolMat is able to withstand 500° F of radiant heat and up to 2000° F with a ceramic backing. Used in 8O% of NASCAR and accepted by NHRA in October 1994.