PRE WASHING | How to Prewash Fabric Before Sewing

I must admit pre washing fabric is not one of my favorite tasks, but when you are sewing or purchasing 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 a few simple steps, you can learn how to pre wash fabric.

Pre Washing - Why & How to Pre wash Fabric

When it comes to pre-washing, people often have a lot of questions as to whether it needs to be done and how to pre wash. While it is tempting to skip this extra step before sewing, you will always get the best results if you prewash fabric first.

Why do Pre Washing?

Prewashing your fabric before you spend time and effect in sewing is important because of:

1. Shrinkage: Fabrics, especially natural fibers like cotton, linen, and wool, have a tendency to shrink after their first wash. If you sew a garment without pre-washing the fabric, you might find it no longer fits. Pre-washing allows the fabric to go through the shrinkage phase before it is cut and sewn, ensuring accurate fitting of the final product.
2. Color Bleeding: Some fabrics, especially dyed ones, tend to bleed color when washed. This can be disastrous if your project involves different colored fabrics sewn together. The dye from one fabric may bleed into another, altering the colors and ruining your design.
3. Remove Chemicals and Dirt: Many fabrics are finished with starch and chemicals to make them look crisp and nice when on the bolt. These chemicals may cause skin sensitivities and should always be washed out before making children's and baby clothing.
4. Softening: Some fabrics change their feel after washing. For example, certain fabrics may soften up, making them easier to handle and sew.
5. Prewashing as a Test: Pre-washing can also serve as a practical test for fabric quality. If the fabric frays excessively, distorts, or its color fades substantially during washing, it's better to know this beforehand than after you've invested time and effort into a sewing project.

And yes, it does often feel like an annoying extra step that you will question yourself doing. But prewashing saves time in the long run and stops you from wasting hours sewing garments that won't look good after the first wash.

How to Pre Wash Fabric, Step by Step

1. Check the Fabric Care Label

Pre washing depends on what kind of fabric you are going to be sewing.

Cotton, linen, denim, rayon, silk and natural fibers should always be prewashed as they are likely to shrink. Synthetic fabrics, while they will not shrink, should still be prewashed to check for color bleeding.

Always check the bolt of fabric for washing instructions at the time of purchase. I have to admit, though, that I do forget to check the label most of the time, so I need to use some common sense depending on the fabric composition and the final use of the project.

MY RED RULE: My rule is always to pre wash anything red. No matter the fabric supplier, I always find that red is the most likely color to bleed. Red and white spots often become pink spots so need to be tested.

2. Finish the Raw Edges

How to prevent fabric from fraying during prewashing? 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.

If you are using a zig-zag, do a wide stitch of length 4 and width 6. A 3 step zig-zag may eliminate any bunching up of a regular zig-zag on fine fabrics.

Further Reading

• How to Use a Serger
• Seam Finishes
• Stop Fraying

3. How to Prewash Fabric Before Sewing

The Pre Washing Fabric Rule; As a general rule, prewashing 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 or pants, then machine wash the fabric before you start.

If your final item will be hand wash only, then hand wash the fabric for pre washing.

Keep some white scraps of fabric handy and throw some in when pre washing. That way, you can easily see if any of the excess dye color transfers onto other fabrics. This is especially important if you are going to be color-blocking your designs.

Further Reading: How to Test for Colorfastness.

Here are some rules that will help you decide on the method of prewashing.

• Cotton - Warm machine wash when pre washing cotton fabric
• Silk - Handwash in warm water carefully or dry clean
• Linen - Cool machine wash or handwash
• Polyester - Cool machine wash
• Rayon - Cool machine wash
• Spandex/Lycra - Cold hand wash only

4. Drying after Pre Washing

Air drying after pre washing fabric can be done by hanging it in the shade so it doesn't fade.

I would not recommend throwing your fabric in the dryer after pre washing. Dryers tend to over-shrink due to the heat. If you have spent hours sewing something with love, you probably won't be throwing it in the dryer when you wash it anyway.

If you just must use a dryer on the finished garment, then throw your fabric in but do so at your own risk.

5. Press the Fabric After Pre Washing

After you have finished pre washing your fabric might look a little sad and crumpled. If you have stubborn wrinkles, give it a gentle press using a water spray and it will look good as new!

Trim any annoying threads or excess fraying, and you are ready to start cutting the fabric for sewing.

How to Test Fabric for Shrinkage after Pre-Washing

If you are worried about what your fabric will look like after pre-washing, you can just test a little scrap instead of the entire piece.

This method is often used in commercial production as it is impractical to wash hundreds of meters of fabric at once.

The dye transfer will be obvious. A white scrap of fabric should still be white.

If, after pre 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 (7.5x7.5cm) – there is 25% shrinkage

If there is 10-25% shrinkage, you would then need to go back and wash the entire amount or alternatively put labels on the clothing advising of shrinkage. For no shrinkage, I normally wouldn't wash the full amount of fabric.

For really large productions, you might use this testing method for a yard (or meter) instead of a small scrap. It just depends on the consequences of shrinkage and how much fabric you can sacrifice for testing.

When Not to Prewash Fabric

Above, we have discussed how to prewash fabric and all the great reasons why you should. In some circumstances, you might want to skip this step. Here's when not to prewash fabric:

1. Dry Clean Only Fabrics: If your label states that the fabric should only be dry cleaned, then you should not prewash. These include fabrics like silk, wool, some synthetics, and leather.
2. Small Precuts: Small precut fabric pieces such as quilting jelly rolls or layer cakes should not be prewashed as they will fray and distort due to their small size.
3. Delicate Fabrics: Don't prewash delicate laces and fabrics with embellishments such as beading or embroidery.
4. Fabric for Quilting: Quilters, including myself, often skip prewashing. Quilting fabric is crisper and thus easy to sew and cut small pieces accurately. My exception for this is when I have a red or dark-colored quilting fabric.
5. Stabilized Fabrics with Interfacing: Some fabrics come with interfacing already attached, and these should not be prewashed as it could cause them to separate or wrinkle.
6. Leather and Faux Leather (Vinyl): These materials should not be prewashed as they can distort and mark with water.
7. Certain Craft Projects: If the final product won't be washed often or at all (like wall decorations), you might choose not to prewash the fabric.

Remember, these are just suggested guidelines for prewashing or not prewashing. The decision to prewash or not largely depends on the type of fabric, the project you're planning, and the end-use of the item you're creating. If you have any doubt, testing a small piece of the fabric can give you an idea of how it will behave when pre-washed.

Pre-Washing Fabric FAQs

Do You Use Detergent When Pre Washing Fabric?

Yes, you should use the same detergent you will use to wash the finished item. In most cases, this will be a mild detergent suitable for your fabric type.

Does Prewashing Fabric Affect its Color?

Prewashing can sometimes fade fabric, especially if it is brightly colored or dark. Poor quality fabrics are also more likely to fade. To avoid fading, or color changes, wash like colors together. Use a cold water wash and air dry in the shade instead of using the dryer.

Pre Washing - In Conclusion

So now you can make a great decision about pre washing and save yourself from frustration later on.

Do you prewash fabric before sewing? Comment below.

I shall cast the first comment – My answer is sometimes. As a general rule, I do it for knits and don't for quilting fabrics if I am using a quality brand that I know doesn't shrink. For purchased clothing, I do if it is a bright color that is likely to bleed. And I always do pre washing on red articles.