Disintegration Residue
Evaluation of the completeness of the pulping process involves measuring the quantity of material that fails to break down into individual fibres. Papermakers define unpulped flake fraction as the mass of paper bundles that are retained on a coarse screen after a set period of mechanical agitation. A high value suggests that the pulping time was insufficient or that the chemical resistance of the material is too high.
This metric is essential for assessing the efficiency of recycled fibre preparation.
Screening Observation
Lab analysis uses a standard sieve to isolate these flakes from the rest of the slurry. When unpulped flake fraction is high, it often indicates that the stock was too thick for the rotor to provide uniform mixing. These bundles of fibres are too large to pass through the fine screens of the paper machine.
They represent a direct loss of usable material if they cannot be recirculated for further processing.
Operational Impact
Production schedules are often delayed by the need to re-pulp batches that show poor disintegration. If the unpulped flake fraction persists into the final headbox, it causes visible defects and weak spots in the finished paper. Consistent monitoring allows for the adjustment of pulping chemistry to overcome stubborn coatings.
