Why pre-wash your fabric before sewing (and when not to)
When I was 14, I fell in love with a really weird fabric. Some kind of psychedelic black-and-white checkerboard pattern. Something hot, right! 😁
I rushed to buy some. Then I made myself a nice pair of wide-leg pants. Which I wore proudly. And of course, I eventually washed them…
And my pants lost 2 inches in length. 😱
My mistake? I hadn't washed my fabric before sewing!
If you don't want the same thing to happen to you as it did to 14-year-old me, keep reading.
Because you can't just buy fabric, head home, and start cutting into it. Well, you can, but odds are you'll eventually run into some unpleasant surprises…
So, how (and why) do you prep fabric before sewing it?
Generally speaking, the best way to prep your fabric is to wash it.
*Small note: there are a few exceptions. I'll get to those.
The main reasons your fabric needs pre-washing before you start your project
📌 Relaxing the thread
What's the warp thread? Let me explain...
Most fabrics are made on a loom, right? On that loom, you've got the warp thread and the weft thread. The warp thread (your straight grain) is the thread mounted on the loom, pulled really, really tight. The weft thread passes from one side to the other (via a shuttle), crossing over the warp threads.
Fabric you buy in a store is wider, and not handmade... but the principle is the same as in the photo above...
Since the warp thread is extra taut while the fabric is being made, you'll want to relax it a bit. Because it's going to relax on its own eventually anyway. And that makes the fabric shrink. So you might as well do it right away, before you start working with it.
📌 Shrinking the fibers
Not all fibers, but many, tend to shrink when washed. Cotton is the most extreme. And the first wash is always the worst. That's why we do that first wash upfront.
In my pants story, I hadn't washed my fabric (apparently I was too excited to wear my weird new pattern). And it was cotton. That's why I lost so much length after washing.
📌 Washing out the finishes
What are we talking about here? Products applied to fabrics to keep them looking nice on the shelf (kind of like the wax on fruit at the grocery store…). This is the case with poly-cottons (or permapress). You know, that really cheap fabric sold in a rainbow of colors… There's often a finish on it. Once washed, the fabric softens up a bit.
If you want the true texture of the fabric, it's best to wash it before you start.
*Watch out here! Some fabrics have a finish you don't want to remove! That's the case with taffeta, for example. If you wash taffeta, it'll lose all its structure... but I'll get to that in the exceptions.
📌 Setting the color
Especially with bright and/or very dark dyes, the color may not be fully set before that first wash. So it's always better to let your fabric shed its excess dye, just to make sure it won't stain… not your fingers, not your machine, not the other clothes it'll be sharing space with in the washer or in your drawers.
Little tip: you can add salt or vinegar to your fabric's first wash. It'll help set the color.
Personally, if I can, I'll run my fabric through both the washer AND the dryer. That way, I know I've shrunk it as much as it's going to shrink (since it's often the heat that shrinks fibers), set the color, and gotten rid of anything that needed to come out. And it's also because I don't like air-drying fabric. It takes forever, and I'm lazy…
When not to wash your fabric
📌 The special case of certain fibers
There are fabrics you don't want to put in the dryer. That's the case with wools, silk, etc. Those fibers are more finicky and require a more delicate wash, and generally no dryer at all.
📌 The special case of certain fabrics
And then, there are also certain fabrics with finishes or coatings that you don't want to lose… That's the case with taffeta. If you wash your taffeta, it's going to become super limp (and that's rarely the point when you're using taffeta).
| Want to learn more about fabrics? I've got an article for you! |
Decating your fabric
If you can't put your fabric in the wash, you can simply steam it with your iron. This is called decating your fabric (it's a weird word, you don't really need to remember it...). It'll relax the fibers without damaging them. And everyone will be happy.
The main thing to remember is that your washer and dryer can alter your fabrics. So you might as well alter them before working with them, to avoid any unpleasant surprises.
A little tip: wash your fabric the way you'd wash the finished garment...
If you're buying denim, you're probably going to make pants (or something super casual) that's going to get washed regularly. Run all that through the washer and dryer.
On the other hand, going back to taffeta, chances are you're planning something fancier that you'd send to the dry cleaner anyway. In that case, don't wash your fabric.
When in doubt, you can always run a piece of your fabric through the wash to test how it reacts (buy an extra 20 cm or so for testing).
Mistakes to avoid
❌ Cutting your fabric before the first wash
This is the basics. Always remember to wash (or decate) your fabric before starting a project. Got a fabric that's been sitting in your workshop for a while and you're not sure if you've already washed it? Someone gave you fabric and you don't know if it's been decated? Don't take the chance, do the process again. Better to do it twice than not at all!
❌ Washing a delicate fabric like it's cotton canvas
Some fibers are more delicate than others. Some fabrics have finishes, special treatments. Don't treat every fabric the same way. Take the time to look at what you've got in your hands: what's the fiber? Is there a special finish? A texture that might not handle washing well? etc. Really understanding your fabric will help you prep it properly.
❌ Assuming all fabrics shrink the same way
Just because you've used cotton denim before that didn't shrink much in the wash doesn't mean the next one will behave the same way. It could have a finish, or a dye that fades a lot, or a looser weave that lets the fabric shift... Not all fabrics react the same way, so don't take chances. Wash your fabric.
❌ Skipping a test
It's always a good idea to run tests. Especially if you're not completely sure about your fabric. It just takes a bit of time, but it saves you a whole lot of headaches!
In summary: how to prep your fabric before sewing
- Check your fabric's fiber content.
- Wash it the way you plan to wash the finished garment.
- Be careful with delicate fabrics.
- When in doubt, test a swatch.
To wrap up my psychedelic pants story… I made a kind of fake cuff out of black fabric, and I was able to wear my pants for a long time after that (probably much to my father's dismay, since he already thought I wore weird enough stuff as a teenager…).
Don't forget to properly prep your fabric next time you're starting a project. And if you do run into an unpleasant surprise, just remember my black-and-white checkerboard pants and tell yourself there's probably some little fix for your blunder. 🤓
| Once your fabric is ready, you can move on to cutting your pattern. Read this article for all my tips! |
And if you want to stay in the loop on new products, promos, and new articles to help you with your creative projects, join The Harbour!
In the meantime,
Happy sewing! Happy crafting! 🤓✂🐙