Phenol sulfonic acid (PSA)is a strong organic acid used as a catalyst in chemical synthesis, a pH adjuster, and an intermediate in producing dyes, pharmaceuticals, and surfactants.

α-Naphtholsulfonic acid polyoxyethylene ether functions in tin plating baths by broadening the optimal current density range for electroplated tin, while rendering tin deposits level, bright and compact.

α-Naphthol polyoxyethylene ether serves in tin plating baths to broaden the optimal current density window for tin electroplating and improve the throwing power of the plating solution, yielding level, bright and compact tin deposits. In addition, EN-10 acts as a dispersant to disperse anodic oxidation degradation products of PSA and its salts, preventing their polymerization and adhesion to the surface of tin-plated sheets.