After refining the fibres must be treated to remove so-called latency
It is created after refining at high consistency and temperature when bent fibres and fibres entangled in fibre bundles are cooled after the discharge from the refiner.
The bent shape becomes permanent when the lignin becomes stiffer.
The strength properties of a sheet become low if the fibres are stiffened in the
bent and entangled form.
The fibres can however be straightened if they are stirred at lower consistency
at a certain temperature
Typical condition for latency removal in a TMP process is intensive
agitation in a chest at concentrations lower than 6 % under at least 10 minutes and at
temperature above 80 °C.
The straitening of the fibres can be seen for example in a reduction of
the dewatering value (freeness),