Elasticity percentage of a fabric
How is calculated?
The elasticity percentage of a fabric is a value to be into account. Before cutting the pieces of a garment, calculate the elasticity percentage of that fabric and verify that it corresponds to the dimensions of the pattern. Otherwise, the fit of the resulting garment will not be the correct. The dimensions of the pattern have to been modifies according to the elasticity of the fabric that we are going to use. Sumarizing, the greater the elasticity of the fabric, the dimensions of the pattern have to be reduced.
Elasticity and Recovery
Before we continue, we define what is Elasticity and the Recovery factor because of this.
Elasticity: It is the result of stretching a fabric to the maximum without being deformed. The elasticity is measure in percent per meter or inch. The elasticity in a fabric can happen in the width, length or bias of the fabric. Or in several senses of the fabric at the same time without that the elasticity percentages coincide.
Bounce: It is the degree of a fabric to recover its initial dimensions after being stretched. The fabrics with good degree of rebound, with a 100% bounce, are those fabrics that recover their original measurements. If the fabric does not recover its measurements, the garment with which is made will be deformed with the use.
Double bounce fabric: The fabrics that have elasticity both the width and the length of the fabric are identify.
How it is elasticity calculated?
- To calculate the elasticity of a fabric cut a sample of 25cm x 25cm. Diminish the selvages of the fabric.
- For check elasticity on the width line, fold the piece in his own half in same direction as grain line.
- On a ruler, stretch the fabric to its maximum without deforming it and take the measure done.
- Once stretched, measure the piece again to check if it has recovered its measurements while in relaxation.
For calculate the elasticity on length or bias line, repeat the method by folding the piece of fabric to the crosswise or bias line.
Calculation of the elasticity percentage
The percentage of elasticity is calculate by following formula:
Elasticity percentage = (final measurement – initial measurement) / initial measurement x 100
A sample that in a 1 meter of fabric is stretch 125 centimetres will have an elasticity of 25%
125-100 = 25 25/100 = 0.025 0.25 X 100 = 25%
If the test for the same fabric we do with a piece of 25 centimetres, the calculation will be
31.25-25 = 6.25 6.25 / 25 = 0.25 0.25 x 100 = 25%
Application to the pattern
If the elasticity is only in the width of the fabric, we apply the calculation only to the total contour measurements. We take as a first measure of reference, the measure that determines the size. For example in a t-shirt, we take the measure of 84cm. breast width. For a fabric with a 25% of elasticity so the piece it has to be reduced the contour to 63cm.
84 – 25% = 63
If the t-shirt consists in two patterns, the chest contour will have to be reduce by 10.5cm. in each pattern. The rest of the contour measurements will be reduce in the same proportion. However, the long ones will remain according to the original pattern.
On the other hand, if the fabric is stretch in two directions, reduction will be apply in both directions. Taking into account apply the percentage that corresponds to each one.
Editor of Seampedia
Fashion Technical Management / Consulting
Model development / Quality control / Production control.
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