Chelators and antioxidants

These are the two ingredients at the smallest percentages doing the most disproportionate work, and the two most often left out of a first formula.

Two different jobs, often confused

A chelator binds metal ions. An antioxidant interrupts oxidation. They are frequently listed together and they protect against different things by different mechanisms.

What a chelator does

Metal ions arrive whether you invite them or not: in water, in raw materials, from equipment, from pigments. Once present they do two harmful things.

They catalyze oxidation. L-ascorbic acid degradation in particular is catalyzed by copper and iron, so a chelator is not optional in a vitamin C formula, it is part of what makes one possible.

And they help organisms, which use trace metals. Tying them up makes a preservative system measurably more effective, which is why a chelator is counted as part of the preservation system rather than as an additive.

What an antioxidant does

Protects the oil phase, and any oxygen-sensitive active, from going rancid or degrading. Its target is the fats rather than the microbiology.

Note the distinction that trips people up: an antioxidant is not a preservative. It stops chemical spoilage, not microbial growth, and a product with a good antioxidant and no preservative is unpreserved.

Why both are cheap insurance

Both are used at fractions of a percent and cost almost nothing per unit. Both address failures that are expensive and slow to detect: an oxidized oil phase and a marginal preservation system both show up months later, in a customer's bathroom.

If a challenge test comes back marginal, adding or increasing a chelator is one of the first things to try, ahead of raising the preservative, because it improves the system without the cost, the irritation risk and the emulsion damage that a higher preservative load brings.

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