At the beginning of 2021, I wrote an article about the importance of washing your fabric before sewing it, and a few weeks ago I was talking about the importance of preshrinking wool... So I thought it would be worth revisiting the subject, given the many questions I receive in the shop and at the sewing studio.
So let's talk about pre-treating fabric, or décatir!
An essential little definition
Décatir means removing the finish known as cati from the fabric.
Cati was originally a starch-based dressing used to make new fabrics firmer and shinier.
Nowadays, however, the term décatir tends to have a broader meaning. It is increasingly used in the general sense of "preparing" fabric before a sewing project.
For the purists among you, please note that we will therefore be using the term décatir in its "broad sense".
But why is it necessary to pre-treat / prepare fabric before using it?
Why should certain fabrics be pre-treated / prepared?
The first reason is that fabric can shrink in its first wash. Natural fibres (cotton, linen, hemp...) tend to tighten during the first wash. Good-quality cotton shrinks only a little; linen and wool a little more, sometimes up to 10%. It is therefore important to prepare your fabric, or you may no longer fit into the garment you took such care to make...
The second reason is to remove the dressing applied by the manufacturer to improve the fabric's finish: removing the "cati", the original meaning of décatir. This dressing gives the fabric a degree of stiffness and stabilises it. It is important to remove this layer before sewing your garment so that you can see the fabric's true drape and decide whether it has the fluidity you want for your garment.
The third reason is that your fabric may release dye, in other words lose some of its colour. The fibres are saturated with pigments that dissolve in the wash water. Blue, black and red fabrics are the most likely to run. Who has never had blue hands after handling a new pair of jeans?
Finally, the fourth reason is that washing removes dust, microorganisms and so on that the fabric may have encountered during manufacturing, transport or storage...
But be careful: not every fabric should be washed!
Which types of fabric need pre-treating / preparing?
All fabrics made from natural fibres need pre-treating / preparing, such as cotton, wool, linen or silk, because these textiles are at risk of shrinking. Remember that regenerated fibres derived from natural fibres, such as viscose, also need pre-treating.
Synthetic fibres such as polyester do not need pre-treating before sewing. And of course, we do not pre-treat textiles such as synthetic leather imitations or non-washable fabrics...
Cotton poplin that needs pre-treating before sewing
Atelier Brunette linen and cotton blend fabrics that need preparing before sewing
Japanese fabrics that need pre-treating before making a kimono (haori jacket)
Which methods are used to pre-treat fabric?
First, make sure you know the composition of your fabric remnant so that you know how it should be washed.
The best approach is to subject the fabric to the washing conditions it will receive once sewn: gentle washing / hand washing, machine washing on a specific programme at a specific temperature, dry cleaning...
Washing the fabric is ideal for pre-treating it, but there are other techniques too.
1. Pre-treating by washing
You can pre-treat fabric by hand washing it or running the wash programme you will use to care for your finished project. However, follow the care instructions for your textile when choosing the washing programme.
This is the method I use most often, but it requires a little forward planning before sewing a project. Another approach is to wash all your remnants before putting them away in your stash; that way, when you feel like sewing a remnant, you know it is ready and you can get started straight away.
2. Pre-treating with steam
Another, more "instant" approach is pre-treating with a steam iron. You can do this if you are in a hurry or do not have time to wash your fabric before sewing it. Steam pre-treatment has the advantage of being very quick, but focuses on removing the dressing. It does not, for example, allow the fabric's excess pigments to wash out.
This technique is even easier if you have a steam generator iron. Its steam output makes pre-treating much more effective and straightforward 😊.
So, ready to sew your projects? How do you prepare your fabrics?
To your needles... or rather your iron 😊!
