disodium edta
what it is
A chelating agent — INCI name Disodium EDTA. Chelators grip trace metal ions, like the iron and copper that ride in with water and raw materials, and hold them out of trouble.
why we use it
Stray metal ions catalyse oxidation and blunt preservatives. At 0.10%, EDTA locks them up, which keeps textures and colours stable and lets the preservative system work properly at a lower dose. It is insurance, priced in hundredths of the formula.
where you'll find it
In feather at 0.10% and in cloud at 0.10%.
evidence
Chelation is textbook coordination chemistry, and its effect on preservative efficacy shows up plainly in challenge testing.
safety
Two criticisms deserve straight answers. Penetration: EDTA can modestly increase the penetration of other ingredients; this is well studied, and the Cosmetic Ingredient Review panel concluded it is safe as used, with EDTA itself barely absorbed. Environment: EDTA biodegrades poorly — a fair criticism, driven mostly by industrial and detergent volumes, of which cosmetics are a small fraction. We use the minimum effective level and are evaluating newer chelators, such as sodium phytate, that could match its performance with a better environmental profile.