Sodium Hexametaphosphate

Uses:
SHMP is used as a sequestrant and has applications with in a wide variety of industries, including as a food additive in which it is used under the E number E452I. Sodium carbonate is sometimes added to SHMP to raise the pH to 8.0-8.6, which produces a number of SHMP products used for water softening and detergents. Also used as a dispersing agent to break down clay and other soil types. It is also used as a homeopathic medical agent against surra, leishmaniosis and sleeping sickness.
One of the lesser-known uses for sodium hexametaphosphate is as a deflocculant in the making of terra sigillata, a ceramic technique using a fine particled slip. The sodium hexametaphosphate causes the heavy particles in the slip to drop to the bottom allowing the fine particles to be siphoned off and applied to a green ware ceramic surface. It is also used as a dispersant for the ASTM D422 - 63(2007) Standard Test Method for Particle-Size Analysis of Soils.
It can be prepared from Na2HPO4 and NaH2PO4.