How much can FAS improve pulp brightness?

Brightness improvement depends heavily on the incoming pulp.

Important variables include:

Wastepaper furnish

Initial brightness

Ink composition

Pulp washing efficiency

Residual metals

pH

Temperature

Reaction time

FAS dosage

Subsequent bleaching stages

Therefore, a responsible supplier should not promise a fixed brightness increase for every pulp.

The recommended approach is:

Customer pulp sample → laboratory trial → optimized dosage → mill trial

The target should normally be expressed as:

Δ ISO Brightness

rather than simply claiming that FAS "provides high brightness."