Engineered to form a monolithic seal after drying. 3M Fire Barrier Sealant IC 15WB+ is a yellow, one-part, gun-grade, intumescent firestop sealant that provides up to 3-hour fire protection in tested and listed systems. This helps prevent the spread of fire, smoke and noxious gas, while also acting as an acoustic barrier to help minimize noise transfer. Color: Light Yellow.