Classification of polyols and isocyanates: components with additives must be assessed individually on merits for excise assessment Polyols and isocyanates presented together for sale, even when containing additives such as fillers, plasticisers, flame-proofing agents, pigments, blowing agents, catalysts or foam stabilizers, must be classified and assessed individually on their merits; these additives are permitted additions that do not alter the constituent products' classification or convert them into a single 'set.' The Board accepts the technical opinion and directs field formations and trade to finalise pending assessments accordingly.