We Formulated This Fire Sealant to Dry and Form A Monolithic Firestop Seal That Also Acts As A Barrier to Airborne Sound Transmission. 3M™ Fire Barrier Sealant CP 25WB+ Is A Red, One-Component, Gun-Grade, Latex-Based, Intumescent Firestop Sealant. This Fire Barrier Sealant Helps Control The Spread Of Fire, Smoke and Noxious Gases Before, During and After Exposure to A Fire.