Measurement of
Spirality in Knitted
Fabrics and Garments
By:
Dr. Subrata Das
Measurement of spirality in knitted fabrics and garments
By: Dr. Subrata Das
Weft knitted fabrics tend to undergo certain dimensional change that causes distortion in which there is a
tendency of the knitted loops to bend over, causing the wales to be at diagonal instead of perpendicular to
the courses.
This is a very common problem in single jersey knits and it may exist in grey, washed or finished state and
has an obvious influence on both the aesthetic and functional performance of knitwear. However, it does not
appear more in interlock and rib knits because the wale on the face is counter balanced by a wale on the
back.
Course spirality is a very common inherent problem in plain knitted fabrics. Some of the practical problems
arising out of the loop spirality in knitted garments are: displacement or shifting of seams, mismatched
patterns and sewing difficulties. These problems are often corrected by finishing steps such as
setting/treatment with resins, heat and steam, so that wale lines are perpendicular to the course lines. Such
setting is often not stable, and after repeated washing cycles, skewing of the wales normally re-occurs.
Evaluation of Spirality:
AATCC Test method 179 -2004:
This test method determines change in skewness in woven and knitted fabrics or twist in garments when
subjected to repeated automatic laundering procedures commonly used in the home. Washing and drying
procedures used for shrinkage tests and other home laundering tests are specified for this method.
For some fabrics the degree of twist of fabric in garments is not solely dependent on its behavior in the
unsewn state; it also may be dependent on the manner of garment assembly.
This method is based on the following principle:
Change in skewness in fabric or twist in garment specimens resulting from procedures typical of home
laundering practices is measured using bench marks applied to the specimens before laundering. Fabrics or
garments that are distorted in their unlaundered state due to faulty finishing of the fabric or faulty assembly
of garments may give deceptive results when laundered by any procedure. In such cases, it is
recommended that specimens not be used, or if used, the results be considered as indicative of those
specimens only.
One of the common methods of measurement of spirality in garment is indicated below:
Figure 1: Inverted T marking
One leg of a right angle marking device is placed along Line YZ so that the second leg is on a perpendicular
downward from point "B". A bench mark is drawn along the perpendicular on line YZ. The intersection of the
bench mark and line YZ corresponds with point A' as depicted in Figure 1. The length of lines AA' and AB is
measured and recorded with a suitable tape or ruler to the nearest millimeter or tenth of an inch or smaller
increment. The point A can be shifted to left or right depending on the direction of spirality.
Calculation:
Percent change in spirality can be represented as follows:
X = 100 x (AA’/AB),
Where, X = % change in spirality
Practical way of measurement:
Determination of spirality in percentage:
• Align the shoulder of the top (Figure 2) or the waist of the bottom (Figure 3) and lay it flat without
tension on the table.
• Gently remove large wrinkles and creases. Begin smoothing at point E working down the garment
body.
• Using marking pen, one spirality mark should be placed at uppermost of the garment folded edge
(point E) and the other spirality mark should be placed at the lower most point of the same folded
edge (Point F).
• Measure and record the distance from point F to point G and measure and record the distance from
point H and point G.
• Then, wash and dry the specimen according to care label as per the recommended procedure.
• Condition the specimen after washing.
• Align again the shoulder of the top or the waist of the bottom and lay it flat without tension on the
table.
• Gently remove large wrinkles and creases. Begin smoothing at point E working down the garment
body.
• Measure and record the distance from point E to point G.
• Measure and record the distance from point F to point G.
Calculate spirality of garments before and after washing using the following formula-
FG
% Spirality = -----------x 100
EG
As per the experience of world renowned retailers in the globe, seam twisting / shape distortion /
spirality greater than 6% in tops and shorts and 4% in skirts, pants, dresses, and sleepwear detracts
from the appearance of the garment.
Determination of angle of wale spirality
• For specimens tested in the original state conditioning is not essential, for processed specimens a
minimum of 4 hours in the standard atmosphere is required.
• Determine accurately the path of the course line; this can be achieved by either placing the base of
the protractor or a rule along the course line or drawing a line parallel to the course with a fine tip
pen.
• Determine accurately the path of the wale line that intersects with the drawn course line, draw along
this wale line.
• Place the protractor along a course line ensuring wale intersects with the bottom of the 90° line on
the protractor (Figure 4).
• The angle between the 90° line and wale line is measured and the direction of spirality (+ right, - left)
is recorded.
• Repeat the process nine more times so that ten results are recorded and the mean is determined.
Notes:
• If any difficulty occurs in finding the accurate course line by eye, unravel a few courses to determine
the exact line before measurement is taken.
• This method can be used on knitted constructions other than single jersey, where spirality is a
problem.
• Relaxation in a conditioned atmosphere 65%±2%rh & 20±2°C is preferable but where a conditioned
atmosphere is not available greater variation in result may occur.
Figure 4: Schematic representation of the measurement of spirality angle
As per the experts and different world renowned buyers, the angle of spirality lesser than 10 degree
is acceptable as performance requirement and it is expected that within that threshold limit knit
loops will not pose any serious problem.
Remarks:
In an ideal situation, the wales on the knitted fabric are to be perpendicular to the course in the lattice
structure. But this is far from being reality due to the fact that the wales are not always perpendicular to the
course and skew to the right or left forming a certain angle of spirality. Due to the open and unstable
structure, looped yarn with its inherent residual torque has the freedom of movement during the relaxation
treatment which relieves the residual torque, thereby uncurls itself inside fabric and transformed to spirality
as an after effect. This downgrades the appearance of the merchandise and may not be acceptable to the
buyers.
