PTSA ( Para-Toluene Sulfonic Acid ): 1. Used for acid-catalyst reaction such as estification, hydrolysis, dehydration, polymerization and alkylation as a catalyst. 2. As hardener of many resin systems, such as resoles, epoxies, amino-Plastics and furniture lacquers. 3. As intermediate of dye chemistry, adhesives and specialized plasticizers. 4. As a hardening agent of furan resin which is applied in foundry Industry (Sand Casting). 5. As an anti-stress additive for electroplating baths.