What it is
Sodium hexametaphosphate is a soluble glassy polyphosphate that binds calcium, magnesium, iron, and other multivalent metal ions. By sequestering these ions it helps prevent discoloration, rancidity, and instability that trace metals can cause, and it can also help control viscosity in water-rich formulas. In sunscreens it is a minor functional additive supporting overall stability.
Safety & warnings
Used at low levels it is generally well tolerated; concentrated phosphate salts can be mildly irritating. It is non-comedogenic and not a known fragrance allergen.
Origin & sourcing
Synthetic, made by heating and rapidly cooling sodium phosphate to form a glassy polymeric salt.
Questions everyone asks
What is sodium hexametaphosphate for?
It is a chelating agent that ties up metal ions in the formula, helping prevent discoloration and instability over the product's shelf life.
Does it affect sun protection?
No. It is a stability aid and does not absorb or scatter UV light itself.