I must admit having to prewash fabric is not one of my favorite tasks but when you are sewing clothing it is a must-do task. Most fabrics will shrink slightly when washed and some will even shrink considerably. Knits, in particular, are prone to shrinking. How would you feel if the dress you spent hours sewing ended up 2 sizes too small after one wash? With a little care and few simple steps you can learn how to prewash fabric before you sew.
How to Prewash Fabric
Well, it depends on what kind of fabric it is. Always check the bolt of fabric for washing instructions at the time of purchasing. As a general rule, prewash the fabric in the same method that you will be using for the finished garment. So if you are planning on machine washing the finished dress, then machine wash the fabric before you start.
It is a good idea to serger or zig-zag the edges of the fabric before washing as some fabrics fray badly on the edges during the wash. (Read how to use a serger)
How to Test Fabric for Shrinkage
If you are worried about what your fabric will look like after pre-washing you can just test a little scrap. This method is often used this in commercial production as it is impractical to wash hundreds of meters of fabric at once. Try this professional technique.
Cut a square 4 x 4 inches (10x10cm). After you have washed it then flatten and remeasure the square.
If after washing it measures
- 4 x 4 inches (10x10cm) – there is no shrinkage
- 6 x 3.6 inches (9x9cm) – there is 10% shrinkage
- 3 x 3 inches (7.5×7.5cm) – there is 25% shrinkage
Do you prewash fabric before sewing? Comment below.
I shall cast the first comment – My answer is sometimes. As a general rule I do for knits and don’t for quilting fabrics if I am using a quality brand that I know doesn’t shrink.