If we have to make a list of things “everyone working in garment industry must definitely know” the first point will always be ” FABRIC – The Raw material”.
Textile in itself is a very vast field but in this article we are only going to talk about fabric parameters that affect apparel production industrially like Type of fabric , CSV Grades, Repeat Variation , Shrinkage,Grain line etc. This article will form the base for upcoming articles where we will be talking about markers ,cut plans ,cutting etc.
Introduction to woven Fabric
Woven – woven fabrics are produced by Interlacement of yarns, perpendicular yarns cross over and under each other, in repetitive manner to form the fabric as shown in figure below. Shirts and denims are made of woven fabric.
Warp – Warp is the set of lengthwise yarns that are stretched over the frame of the loom in such a way that a filling yarn can be inserted between them to form the weave.
Weft – The yarns that are inserted between the warp are called Weft. They are sometimes also referred as filler.
Arrangement of warp and weft to produce designs called weave. And this arrangement can be varied to give us many different types of weave.
The basic weaves are:
C. Satin and sateen
Woven Fabric parameters that affects stitching
1. Selvedge – In woven fabric, Selvedge is the edge of the fabric running parallel to the warp. It is formed because the weft thread returns back at the end to make next filling between the warp. Since a single weft yarn loops to and fro over and under the warp, the fabric does not fray from the selvedge. It is interesting to know that that the word selvedge has been derived from ‘Self – Edge’.
2. Grain line – Grain line refers to the direction in which a pattern is placed on the fabric. Generally Grain line is placed parallel to selvedge but in some cases to alter the behaviour of fabric or visual appearance of a print or pattern, designers may change direction of grain line.
Grain line should be parallel to selvedge because warp thread is stronger and is kept stretched during weaving so it is least likely to stretch therefore if fabric is cut in this direction the dimensional stability of the garment will be better and garment parts will not twist.
To identify the grain line in a fabric, stretch the fabric in both directions, the direction which stretches less is the warp and hence it is the grain line. Bias grain line (45 degrees) stretches the most and is used in garment parts where high stretch is required. This article on cuttingclass beautifully explains Grain line in detail. link
3. Shrinkage – Fabric has a tendency to shrink or expand after washing. Industrially, shrinkage is used to refer to shrinkage as well as expansion. It is measured in percentage where ‘-‘sign refers to shrinkage and ‘+’ sign refers to expansion. Fabric shrinks/expands in lengthwise as well as breadthwise direction hence it is measured as warp shrinkage (warpwise) and weft shrinkage (weftwise).
For example if a fabric has warp shrinkage = +2% and weft shrinkage = -2% that means that the garment will expand 2 % in warp direction and Shrink 2 % in weft direction(image 2).
How does shrinkage affect garment manufacturing and stitching?
It is a known fact that that buyer specifies measurements in which a garment of particular size has to be made. If shrinkage is not taken into consideration, it is likely that the garment will fall out of measurement tolerance. To ensure that the garment does not fall out of measurement patterns are modified based on the warp and weft shrinkage.
4. CSV (Centre to Selvedge variation)– CSV stands for centre to selvedge variation. For solid fabrics Shade of the fabric varies between centre and selvedge. This variation is called Centre to selvedge variation(image 3).
Fabric shade is compared on a grayscale. There are 10 grades of shade variation on grayscale but for garment production fabric can be classified in only 3 grades, which are :
Grade 3 to 4
Where grade 4 means very minimal variation and grade 3 means maximum shade variation. Grades greater than 4 is not produced and lesser than 3 is rejected for possessing more shade variation.
Note that only solid fabrics will have CSV variations since checks and stripes are yarn dyed CSV will not be exhibited by them.
How CSV Grade affect Garment manufacturing
Depending upon the grade the markers are altered to ensure that all parts one garment are cut on minimum shade variation.
5. Repeat Variation – The pattern or repeat is the smallest unit of the weave which when repeated will produce the design required in the fabric. The size of the repeat varies in lengthwise and breadthwise direction this is called as repeat variation. It is measured by a measuring tape and the unit of measure is millimetres.
If the repeat size in any fabric is 2 mm the number of repeats contained in 10 mm should be 5 but it will vary this difference is called repeat variation.
6. Bowing: Bowing refers to a state in fabric where the ends of weft(filling) yarns are straight to each other but is drawn away at the centre forming a bow like structure. It is measured as maximum displacement of weft yarn from being in a straight line as the ends.
7. Skewing: When the weft thread are not straight but slanted then the fabric is called be skewed.
How to measure bowing and skewing:
8. Fraying: Unravelling of yarns from the weave is called is called fraying. Fraying fabric is handled by factories by anti- fray sprays.