What it is
Sodium chloride is an ionic compound with the formula NaCl, a 1:1 pairing of sodium and chloride ions that forms colorless cubic crystals and occurs naturally as the mineral halite. In cosmetic formulas it is best known as a thickener: adding a small amount, typically around 1-3%, can turn a runny surfactant solution into a gel-like texture by screening the electrostatic repulsion between surfactant molecules so they form entangled, elongated micelles. It can also act as an emulsion stabilizer in water-in-oil systems and, in undissolved form, as a physical exfoliant in scrubs. In sunscreens it serves a formulation role and is not a UV filter.
Safety & warnings
Sodium chloride is the same salt found in food and seawater and is a familiar, broadly tolerated cosmetic ingredient. In leave-on products its main practical drawback is that high levels can feel drying, and undissolved crystals used as a scrub can be abrasive on delicate or compromised skin; patch testing remains wise for very sensitive skin.
Origin & sourcing
Sodium chloride occurs naturally as the mineral halite (rock salt) and dissolved in seawater and brine. It is obtained by mining rock salt and by mass-producing salt through evaporation of seawater or brine from brine wells and salt lakes.
Questions everyone asks
Why is table salt in my sunscreen?
It is used as a formulation aid, most often to adjust thickness or stabilize an emulsion, not for sun protection. It is not a UV filter.
Will salt in skincare dry out my skin?
At the small levels typically used as a thickener it is generally fine. Higher concentrations or salt scrubs can feel drying or abrasive on sensitive skin.
Is cosmetic sodium chloride the same as table salt?
Chemically yes, it is the same compound, NaCl, sourced from rock salt or evaporated seawater.