What is Crimp% in Fabric and How to Measure Warp and Weft Crimp%

What is Crimp%?

You might know that woven fabric made of two sets of yarns - warp yarns and weft yarns. Warp and weft yarns are interlaced with each another and form fabric sheet. Inside the fabric, yarns form a wavy shape instead of straight yarn. As a result actual length of the yarns is longer than the length of fabric width and length in fabric. Both in warp way and weft ways. The shortening of yarn length in fabric is known as crimp.

Crimp in woven fabric

To calculate yarn requirement for a particular fabric, you need to know crimp of the yarns in the fabric.
Crimp% in woven fabric varies depending on fabric structure - like yarn density and yarn thickness.

How to calculate Warp/Weft Crimp%: 

Use the following steps to find crimp% of warp and weft yarns.

  • Take a fabric sample of 1 meter X 1 meter
  • Pull out warp and weft yarns (of full length) from the fabric sample
  • Remove crimp from yarns and straighten to its actual length 
  • Measure the length of the straighten warp and wefts. Assume that you got straighten length of warps are 1.05 meter and weft yarn length is 1.08 meter.
Then calculate crimp% by using following formula.
Yarn Crimp% = 100 X (Straighten Yarn length - Yarn length in fabric)/Fabric Length

Warp Crimp% = 100 X [(length of warps in straighten form - warp wise fabric sample length)/Warp wise fabric sample length]

Weft Crimp% = 100 X [(length of weft in straighten form - weft wise fabric sample length)/Weft wise fabric sample length]

Example:

From the above information

Warp crimp% = ((1.05-1.00)/1.00) *100 = 5%
Weft crimp%= ((1.08 -1.00)/1.00)* 100 = 8%

Crimp% is also needed when you need to calculate Fabric GSM from its construction.

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