Hard Char

Harder chars are produced with sodium silicates and graphite. These products are suitable for use in service penetration firestop seals, as well as exterior steel fireproofing. In those applications, it is necessary to produce a more substantial char capable of exerting quantifiable expansion pressure.

In the case of a service penetration firestop seal, a burning plastic pipe that’s melting for example, must be squeezed together and shut off, so that there will be no opening for fire to propagate through the fire-resistance rated wall or floor assembly. The expanding intumescent will push against the softening plastic and close any void that is formed with a protective char thus, preventing the fire from going through the penetrated fire separating element.