KSS is extremely effective as a flame retardant additive with premium performance in polycarbonate at very low additive levels.FR-KSS, a non-halogenated product, is said to provide excellent FR effectiveness at fractional loading levels of less than 1 wt% in a PC formulation while maintaining the transparency inherent in the thermoplastic. A white powder, it is the potassium salt of a complex of diphenyl sulfone sulfonate and diphenyl sulfone disulfonate. For most effective incorporation it is recommended that the additive be initially dispersed into a 10% or more masterbatch and then compounded into the final plastic blend. Dispersion can be achieved effectively with typical polycarbonate processing equipment.