Question 1

What does Sodium Metabisulphite do in a cosmetic formula?

Accepted Answer

This ingredient is used mainly as an antioxidant and preservative-support agent, helping slow oxidation and discoloration in water-based formulas. It can also help protect fragrance, color, and active ingredients that are sensitive to oxygen.

Question 2

Is Sodium Metabisulphite clean?

Accepted Answer

From a clean-beauty perspective, it is a functional but somewhat caveated ingredient because it can trigger sensitivity in a small subset of users and may require label disclosure above low thresholds. It is not usually treated as a broad clean-standard dealbreaker, but it carries more irritation and sensitivity friction than gentler antioxidant systems.

Question 3

Is Sodium Metabisulphite sustainable?

Accepted Answer

This material is an inorganic, chemically manufactured salt rather than a renewable plant-derived ingredient. In water, it breaks down and oxidizes into simple mineral end products, so persistence and bioaccumulation are not major concerns.

Question 4

Is Sodium Metabisulphite COSMOS-approved?

Accepted Answer

It may be permitted in COSMOS-style natural formulations when used for an allowed technical purpose and within applicable limits, but it is not a strong renewable-feedstock story. Its Green Chemistry fit is mixed, with useful low-dose performance and limited persistence, balanced against synthetic manufacture and sensitivity considerations.

Question 5

How does Sodium Metabisulphite work chemically?

Accepted Answer

The molecule is a reducing inorganic salt that releases reactive sulfur-oxygen species in water, which is why it can intercept oxygen-driven color and odor changes. It is most effective in acidic to mildly acidic systems, is less stable as pH rises, and is typically used at low fractions of a percent because performance and sensitivity thresholds are both dose-dependent.