Can FAS replace Sodium Hydrosulfite?

In many applications, FAS can be evaluated as an alternative to Sodium Hydrosulfite (Sodium Dithionite, Na₂S₂O₄).

However, the replacement should not be based simply on a kilogram-for-kilogram comparison.

The correct comparison should be:

Same pulp → same target brightness → optimized dosage → total chemical cost → final pulp quality

FAS and Sodium Hydrosulfite have different chemistry and decomposition behavior, so the optimum dosage and process conditions need to be established through laboratory and mill trials.