Sodium hexametaphosphate

Sodium hexametaphosphate (SHMP) (E452(i)) is a hexamer of composition (NaPO3)6. "Sodium hexametaphosphate" of commerce is a mixture of polymeric metaphosphates, of which the hexamer is one, and is usually the compound referred to by this name. It is more correctly termed sodium polymetaphosphate, CAS 50813-16-6. It is prepared by melting monosodium orthophosphate, followed by rapid cooling. SHMP hydrolyzes in aqueous solution, particularly under acidic conditions, to sodium trimetaphosphate and sodium orthophosphate. SHMP is used as a sequestrant and has applications in a wide variety of industries, including as a food additive. 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.

Ceramic Process
One of the lesser-known uses for sodium hexametaphosphate is as a flocculent 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 of and applied to a green ware ceramic surface.

Other names

 * Calgon S
 * Glassy sodium
 * Graham's Salt
 * Hexasodium metaphosphate
 * Hexasodium salt
 * Metaphosphoric acid

Found In
Sodium hexametaphosphate is listed in the contents of various Lipton Tea products. It indicates it is used to "protect flavor".

It is also found as a "flavor protector" in Code Red Mountain Dew.

It is listed in the ingredients of Sobe "No Fear" Gold brand energy drink.

It is listed in the ingredients of Aunt Jemima Lite Syrup and NOS High Performance Energy Drink.

It is listed in the ingredients of a Quaker granola bar (Chewy S'mores)

It is listed on Sunny Delight (main listed ingredient).

It is listed on Hawaiian Punch.

Additionally, it is listed as a medicinal ingredient in Crest Pro-Health toothpaste, with a concentration of 13.0% w/w.