BYK P 9904 is a processing additive/compatibilizer used in the production of rigid and flexible foams. BYK P 9904 supports faster emulsion formation between blowing agents and polyols in rigid foams, improving compatibility between polyol blends in flexible foams. It stabilizes smaller droplets and prevents phase separation, resulting in a more homogeneous distribution and finer cell structure. BYK P 9904 is recommended for use between 0.2-2% as supplied, based on prepolymer or polyol blend. Optimal levels are determined through testing. It is preferably incorporated with main components to achieve optimum incompatible component droplet distribution. BYK P 9904 enhances material properties through improved component compatibility important for high-performance applications in Advanced Materials industries.