The fibre orientation in the wood is seldom fully parallel with the grinding surface.
The fibres are therefore gradually pulled out after a large number of grits have acted on them.
During this process the fibres are bent 90 degree before they are released from wood structure.
It can be easily understood that most of the fibres easily can be broken even though they are
well softened. The fibres are most likely to be further shortened by the treatment in the transport
out from the grinding zone