"This eerie looking material is a sprayed-foam insulation product that is popular in single-family dwellings for its ease of installation and insulating properties. A similar product can be poured into building cavities to slow air infiltration. A polyurethane derivative, this particular product is made from two components that are mixed on the job before application. In the liquid spray form, the material expands about 100 times its original volume as it dries into these shapes. Once it has dried, the material can be destroyed by flames, but it will not sustain combustion. The material should not be installed within 2 inches (50 mm) of a heat-emitting device where the temperature can exceed 180 °F (82 °C). It cannot be used in electrical outlet or junction boxes. When tested in accordance with ASTM [American Society for Testing and Materials] E-84, 'Test Methods for Surface Burning Characteristics of Building Materials' (the Steiner Tunnel test), the product has a flame spread index less than 20, smoke development index less than 400, and a fuel contribution of 0."
Coffee Break Training - Fire Protection Series No. FP-2009-16
United States Fire Administration: http://www.usfa.fema.gov/