Fabric shrinkage is one of the main concern points when producing apparel. It can affect the consistency of the sizing and the fit of your garments.
In this article, we'll walk you through everything you need to know about fabric shrinkage and how to solve it.
When should I do a shrink test?
It is recommended to do a shrink test on every fabric that you are looking to use. And you should do it BEFORE you commit to using it.
What causes fabric shrinkage?
Exposing it to a combination of moisture, heat, chemical treatment, and/or mechanical action (washing machine) can cause the fibers to release the high tension created during the manufacturing of the fabric, which will then deform the shape of the fabric. The shrinkage can result in either an expansion or contraction of the fabric.
Are some fabrics shrink more than others?
Shrinkage can occur in both knit and woven fabrics. Typically natural fabrics such as cotton, linen, wool, and silk are more prone to shrinkage, while synthetic fabrics such as nylon, polyester, and acrylic are more stable.
Shrinkage is also more common in low-quality fabrics that use less stable yarns that have more stretch in them can deform more easily.
How to perform a shrink test?
Make a square pattern piece from a hard paper pattern that measures 12.5" by 12.5."
Lay that pattern piece on top of the fabric you are testing, and cut the square out of the fabric.
Using a permanent marker, mark the warp (length of the fabric) with an arrow.
Run the fabric through a shrinkage process (re: washing, heat drying, ironing, dry cleaning, etc.). Note: if the fabric frays easily, then you might want to merrow/overlock it lightly so it will not fray during the test. However, make sure that the final measurements of the piece you're testing did not change before testing.
Lay it flat on your cutting table. (If you're using a washed denim, do not steam or iron the fabric after the wash cause it will affect the measurements).
Measure the fabric in both directions.
How to calculate the shrinkage amount?
If you measured the fabric and noticed that it shrunk, calculate the % of shrinkage using the following formula:
Every 1/8" shrinkage should be counted as 1% shrinkage. For example, if the weft (width of the fabric) is measured after the test 12 1/8", that means that there is a shrinkage of 3/8" in the weft, and that is equal to 3% shrinkage in the weft.
How do I solve the issue for production?
You can use one of these two solutions:
Build the Shrinkage percentage back into the pattern (your grader can do that digitally). When you do that, you will cut and sew your product just like any other product and just let your customers know that there might be some small shrinkage after the wash. Most times, if the % of shrinkage is small, the fabric will shrink when the product is being ironed before packing.
Preshrink the fabric before you cut it for production.
Which solution is right for me?
There are few things to consider before deciding which of the above two methods to use. It depends on the amount of shrinkage, in what direction it is, the cost of the fabric, how many yards you are producing, the processes that your garment will go through during production, and the type of fit and style of the garment.
But here are few things to consider:
Generally speaking, if the shrinkage is only in one direction and measures below the 7-8% mark, you can build the % back into the pattern.
However, if the % is more than 7-8 %, it's recommended to preshrink the fabric before cutting.
When the shrinkage shows in both directions, it will depend on the shrinkage % in each direction. If the shrinkage is not equal between the two directions, for example, the weft is 1%, and the warp is 7%, then you'll most likely need to preshrink the fabric, although it will depend on the fit and the styles that you're making, (ask your grader for their recommendation).
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