It is available as white and colorless crystalline granules and powder.
Sodium Tripolyphosphate (STPP) is completely soluble in water. Its solution in water is alkaline.
Its density at 20 °C is 2.52 g/cm3.
Its melting point is 622 °C.
Its pH is between 9-10 (25 °C).
It is stable. Incompatible with strong oxidizing agents and strong acids. It is hygroscopic.
It has a strong solubility in water as solubility. The solubility effect here varies with pH and temperature.