Calculation of flame retardant fabric shrinkage and fabric folding thickness

Classification:
flame retardant fabric

Shrinkage of fabric
There are two types of clothing fabrics: natural fabrics and chemical synthetic fabrics
a: Natural fabrics: woven from natural fibers, mainly plants, such as cotton, Flame-retardant clothlinen, etc., which have a large shrinkage rate, and animals such as: silk, wool, and leather. , shrinkage school

b: Chemical synthetic fabrics: Flame-retardant fabrics are woven from chemical synthetic fibers, mainly polyester, nylon, acrylic, chlorine fiber, chlorine fiber, etc., which do not shrink.
(The other kind is a mixture of natural and chemical fabrics, such as polyester and cotton, with low shrinkage)
Due to the characteristics of natural fabric flame retardant fabrics, natural fabrics shrink after washing. Cotton and linen fabrics that shrink greatly are significantly flame retardant fabrics in daily life, especially casual clothing. Most of them are made of pure cotton fabrics, so when producing paper patterns, Shrinkage must be considered.

Assume the shrinkage rate: a, the size before washing is m, and the size after washing is n, then a=m-n/m*100%
Since the fabric has two yarn directions: transverse and longitudinal, there are also two shrinkage rates:
a vertical=m vertical-n vertical/m vertical*100%
a horizontal=m horizontal-n horizontal/m horizontal*100%
Generally speaking, the shrinkage rate of the fabric will be informed when the pattern is produced. If we do not know the shrinkage rate of the fabric, we can use the following two methods to obtain the shrinkage rate.
a: Ignore the shrinkage first, just make a paper pattern of intermediate size to make a board, and then take it to the water washing factory for washing (note that the washing method must be the same as that for bulk products). After washing, Go and measure this board, compare it with the finished product specifications, subtract more and add less. In this way, the board made of flame-retardant cloth will be more accurate, but it will take too long to make the board.

b: Take a piece of fabric for large goods, sew around it, use a pen to draw a square in the middle of the cloth, with a side length of 40cm, parallel grains on both sides, and vertical grains of 40x40cm on both sides, and then wash, the washing method is the same as for large goods. After washing it back, and then measuring each side of the square, it becomes 36x36cm data.

Reuse a=m-n/m*100%
a vertical 40-38/40*100%=8%
a horizontal =40-36/40*100%=10%
Therefore, the shrinkage rate of the fabric: straight: 5%, horizontal: 10%
However, considering the fixing effect of the sutures, the shrinkage rate of flame-retardant fabric clothing is actually slightly smaller, so it should be determined based on the specific situation.
Find the length of a and the width of a. Use the length of a to find the length and the width of a to find the girth.
The purpose of finding the shrinkage rate is to find the data before washing.
Then it is derived: K vertical=e vertical/1-a vertical (find the length of clothing)
For parts that are directly connected horizontally, the shrinkage rate is the average value, such as the waistband and trousers fabric grains are perpendicular to each other.
Example: w: 66cm-68.6cm (shrinkage: 3% vertically/4% horizontally)
Fabric fold thickness
Fabrics are divided into thicknesses, and garments made of flame-retardant fabrics also have thicknesses; this thickness is expressed by the folding amount, so the folding amount needs to be considered when making paper patterns. The folding amount indicates the folding thickness of the fabric. Any garment has a folding amount. The only difference is the size. The thicker the fabric, the greater the folding amount; the thinner the fabric, the smaller the folding amount.

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