Definition:
"Spirality" arises from twist stress
in the constituents yams of plain fabric, causing all loops to distort and
throwing the fabric wales and courses into an angular relationship other than
90 degree.
Reasons:
Plain knitted fabric made from single cotton yam are
most prone to spirality, the degree being related to the number of twist/unit
length in the yam. Such yam is said to be "twist lively" and, unlike
similarly constructed yams produced from thermoplastic fibers, cannot be heat
set in yarn or fabric form to eliminate spirality.
Measurement:
Spirality is
measured by the number of degrees of distortion that the fabric is away from a
90o relationship of wale to course. Fabrics of around 10o spirality are commonly
processed, although acceptability varies with the quality, price bracket, and
end use of the particular goods.
Treatment:
Resin treatment known as cross-linking is sometimes
used to reduce the degree of distortion due to spirality. The resin is applied
to the fabric in aqueous solution and is set by passing the fabric once through
a high temperature stenter. Besides eliminating some or all of the spriality,
improved dimensional stability, appearance and handle are claimed for this
process. However, it will weaken the strength of the cotton fabric.
How to
avoid it:
Spirality is minimized by the use of double
(two-fold) yams, but this pushes up the price prohibitively in all but the most
expensive garment. Spirality does not occur in IXI rib and interlock fabrics,
the loops formed in opposite directions cancelling out the distortion.
How
about the number of feeders on Spirality:
Another mild form of spirality occurs in fabrics
produced on multi-feeder circular machines, because the number of course
knitted in one revolution of the machine distorts the wale/course relationship.
For example, a 30 inch diameter machine with 90 feeders of 20 gauge will knit
approximately 3 inch of fabric every revolution. This will produce, if the
fabric is finished 90 inch open width. 2 o of spirality.
Fabrics of around 10o spirality are commonly processed, although acceptability varies with the quality, price bracket, and end use of the particular goods. Perth Fridge Repairs are very important in our homes.
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