Does FAS cause brightness reversion?

Brightness stability should be evaluated after treatment.

A useful test program is:

Initial brightness → 24 h → 7 days → accelerated aging

The customer can then compare:

Δ Brightness after aging

between:

Untreated control

Sodium Hydrosulfite

FAS

FAS + H₂O₂

This is particularly important when the pulp is intended for high-brightness writing and printing grades.