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Sodium hexametaphosphate (SHMP) is a hexamer of composition (NaPO3)6. Sodium hexametaphosphate of commerce is typically a mixture of polymeric metaphosphates, of which the hexamer is one, and is usually the compound referred to by this name.
S 1975 (OTTO) Sodium hexametaphosphate, pract Cas 68915-31-1 - used as a paint thinner; in some types of photocopier.