is trisodium phosphate salt
From Wikipedia, the free encyclopedia. Trisodium phosphate (TSP), is a cleaning agent, stain remover and degreaser, commonly used to prepare surfaces for painting.It can also be called trisodium orthophosphate and has the chemical formula Na3PO4. It is a highly water-soluble ionic salt.Solutions of it dissolved in water have an alkaline pH. It can also be found as a food additive; it is used as an acidity regulator (buffering agent), emulsifier, thickening agent, nutrition enlargement agent and sequestrant (metal-chelating agent).t is a highly water-soluble ionic salt. Solutions of it dissolved in water have an alkaline pH. It can also be found as a food additive; it is used as an acidity regulator (buffering agent), emulsifier, thickening agent, nutrition enlargement agent and sequestrant (metal-chelating agent).