Sodium tripolyphosphate (STPP) is used in the production of refractory castables and as a dispersing agent in other ceramic processes. Here are some of its properties and uses: 

• Dispersing agent: STPP improves the rheological properties of concentrated mineral systems, such as corundum mortars, dry castable mixes, and kaolin suspensions. 
• Sodium tripolyphosphate (STPP) is an inorganic compound with the chemical formula Na₅P₃O₁₀. It’s the sodium salt of the polyphosphate penta-anion, which is the conjugate base of triphosphoric acid.
• STPP is a colourless salt, which exists both in anhydrous form and as the hexahydrate.