What exactly is FAS?

Formamidine Sulfinic Acid (FAS), is a sulfur-containing reducing agent used in various bleaching and de-colorization applications.

In the pulp and paper industry, FAS can be used as a reductive bleaching agent for recycled pulp, particularly where improved brightness and color reduction are required.

Unlike hydrogen peroxide, which is an oxidative bleaching agent, FAS works through a reducing mechanism.