During the refining of mechanical pulps the fibre is subjected to significant curling and twisting forces as the fibres are separated from each other and subjected to fibrillation. As a result pulp removed from the refiner will be found to contain aggregates of fibres 'frozen' into a twisted, kinked and distorted shape. This effect is known as latency. If disintegrated at low temperatures, subsequent testing will not show the full development of the properties and the freeness will be falsely high. Disintegration must be performed at elevated temperatures and low consistencies to allow the hemicellulose-lignin structure of the fiber to soften and the residual stresses in the cellulose to be removed. This process is called 'latency removal" and is a critical step in the characterization of mechanical pulps.

We recommend that all mechanical pulps be prepared as per TAPPI T262 prior to physical testing.