Soudal B2 Gun Grade Expanding Foam - 750ml - Champagne Soudal B2 Gun Grade Foam is a fire rated expanding foam that swells up to 3 times when exposed to high temperature. By swelling Soudal B2 foam creates an airtight seal around critical joints preventing passage of fire and smoke. Soudal B2 Fire rated foam can be used for filling gaps in all types of building materials including wood, plasterboard, metal and brick. B2 Expanding foam dries very quickly and can be cut, sanded or overpainted in just one hour after application. Once cured Soudal B2 is resistant to water, heat and ageing. Foam offered is not UV resistant so should be overpainted or covered with sealant if UV exposure is inevitable. 1 can contains 750ml of compressed foam that will expand up to 30 times on application.