Spirality is a regular deformation (skewing) of the knit structure due to the yarn twisting within the structure, so that the vertical lines of stitches (the wales) are no longer at right angles to the horizontal lines of stitches (the courses).

Spirality in knitwear is caused by using an “unbalanced” yarn ie. a singles yarn or a two fold yarn where the incorrect ratio of singles to folding twist has been used.

When spirality occurs in a fabric there is little or nothing which can be done in finishing to alleviate it and usually the only option is to use replacement yarn having balanced twist. However, sometimes spirality can be prevented by steam setting an unbalanced yarn when knitted in a single bed structure, and also some yarns which cause spirality can usually be knitted in a rib structure, since skewing tendency on the front and back beds should cancel out.