Intumescent Coating

Intumescent coatings, also known as intumescent paint, are applied to structural members as an aesthetically pleasing fireproofing product. The coating is used in buildings as a passive fire resistance measure.  Intumescent coatings work by undergoing a chemical reaction when heated to form an expanded, thermally insulating layer.  

 Intumescent coatings protect steel from getting too hot by swelling and charring in the event of a fire, becoming an insulating layer for the metal substrate. These coatings are rated by how long they provide  protection of interior steel against structural failure — typically from half an hour to four hours.