Para Toluene Sulphonic acid is used in the manufacture of phthalate plasticizer, Resin hardener, and as esterification reaction catalyst. It is used as a catalyst for curing cold setting foundry cores in plastics, coatings intermediate, hardening agent in plastics, activator for nicotine insecticides, descaling agent in metal cleaning in electroplating baths. Use as catalyst in hardening of Phenolic resins used in foundry industries.