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Cortex

Diagram of the cortex of wool fibre.

The cortex – the internal cells - make up 90% of the fibre. There are 2 main types of cortical cells – ortho-cortical and para-cortical. Each has a different chemical composition. In finer fibres, these two types of cells form in two distinct halves. The cells expand differently when they absorb moisture, making the fibre bend - this creates the crimp in wool. In coarser fibres, the para-cortical and ortho-cortical cells form more randomly so there’s less crimp.

Fibre crimp makes wool feel springy and provides insulation by trapping air.

Image: University of Waikato

Rights: The University of Waikato Te Whare Wānanga o Waikato
Published:08 February 2018Size: 129.91 KB