First, Let's talk about what causes shrinkage on fabrics. Shrinkage on fabric is mainly due to yarn swelling and the result crimp increase during washing in the case of cotton fabrics. Yarn swelling percentage is more in polyester cotton blending yarn. There are different types of shrinkage that make a fabric shrink among them we have: the Relaxation shrinkage, Felting shrinkage, Compressive shrinkage and Residual shrinkage.
So, with no further interruptions lets move on and calculate the shrinkage of a piece of fabric that has been washed and has shrunk after wash. I must mention before I start calculating the shrinkage for this piece of fabric that this is only one method of many existing methods to test fabric shrinkage. Shrinking results might vary according to the fabric shrinkage method you use and by no means the result of any method used should constitute or govern as final shrinkage result to be apply to production patterns.
Shrinkage results from a calculation will give us a good start to know how much shrinkage we should apply to a pattern not forgetting other factors that modify or alter the shrinkage applied to a garment and therefore we take into account all other factors and adjust shrinkage on a pattern accordingly. Some of the factors that could contribute that a garment does not reflect the shrinkage calculation applied to a pattern are: washing temperatures, types of seams used on a garment, fusible fabrics on waistbands, quality of fabric used, recovery factor etc..
Let's Get Started:
Step 1). Cut a square of fabric from a roll and Draw a square 18"x18" on the fabric. Make sure you are using a fabric marker and that your square is at least 2" away from salvage.
Measure Square Before Wash
18"x18" square block before shrinking
Length wise measurement =18"
Width wise measurement = 18"
Step 2). Wash your fabric sample following your standard washing method to find the shrinkage percentage to washing then let dry. Measure square after wash.
18"x18" square block after shrinking results
Length wise measurement =17"
Width wise measurement = 15"
Step 3). Apply Fabric Shrinkage Formula:
[Width of square block before shrinking] - [width of square block after shrinking] / width of square block before shrinking x 100
Length wise total shrinkage percent Formula: [(18 - 17) / 18] x 100 = 5.55% = 6%
Width wise total shrinkage percent Formula: [(18 - 15) / 18] x 100 = 16.66% = 17%
About the Author
Alejandro Esparza: Co-Founder @ smart pattern making.com /Professional Pattern Maker/ Technical Designer/ Startup Advisor and acknowledged in the garment industry as authority in pattern making and pattern design process. He has the ability to work with small entrepreneurial companies’ private label customers and large organizations. Alejandro is a graduate of Los Angeles Trade Technical College Fashion Design Program. He has over 25 years of apparel garment industry experience and is part of Expert Ezine Articles Authors community since December 25, 2008 and has published multiple articles about the garment industry.
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