The major use for trisodium phosphate is in cleaning agents. The pH of a 1% solution is 12, and the solution is sufficiently alkaline to saponify grease and oils. In combination with surfactants, TSP is an excellent agent for cleaning everything from laundry to concrete driveways. Trisodium phosphate is an approved flux for use in hard soldering joints in medical grade copper plumbing. TSP is still in common use for the cleaning, degreasing and deglossing of walls prior to painting.