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Prewashing fabrics, as the title suggests, is a very important preparation step before cutting! You can skip it – but it’s not worth it! Let’s start at the beginning, with the purchase.
I often hear people ask in fabric shops whether a certain textile needs to be prewashed. My answer is always yes. Always, every single one of them.
It’s worth asking the shop assistant how much the fabric you intend to buy will shrink, and purchasing accordingly. When calculating the allowance, also keep in mind what I wrote about straightening fabric edges – fabrics are not always cut straight in the shop. So my advice is: shop carefully. Don’t regret that extra few centimetres; you’ll be grateful for the surplus when cutting.
During industrial fabric production, a wide variety of fibres, dyes, and other chemicals are used. Natural fibres change their shape when exposed to heat – they generally shrink. Nowadays, there’s a wide range of blends where natural fibres are mixed with synthetic ones in various proportions to influence the fabric’s properties. That’s why it’s difficult to give a single chart showing exactly how much each type of fabric will shrink.
Preventing shrinkage and deformation – most natural fibres contract when they first come into contact with water. When mixed with synthetic fibres, their elasticity and fibre structure stabilise during prewashing.
Colour release – many textiles release some dye during the first wash, as the excess dye used in manufacturing leaves the fabric during prewashing. That’s what we usually mean when we say that a fabric “bleeds” or “runs”. 😊
Softer feel – the starches and finishing agents used in production wash out. You’ll notice that the stiffness or any unpleasant odour disappears.
Safety – this way you’ll know exactly how the finished garment will behave during everyday use.
One of the most important yet often skipped steps in sewing is prewashing the fabric. Who hasn’t been frustrated when a freshly sewn blouse or pair of trousers shrinks, stretches, or loses shape after the first wash? The simplest way to prevent this is to give the fabric its “first wash” before cutting. It’s also worth remembering prewashing when altering a factory-made garment. This issue often appears when shortening trouser legs: you buy them, have them hemmed in the shop or by a tailor, then after the first wash they shrink – because the fabric wasn’t prewashed before production. Quite annoying, isn’t it?
Preparing the water:
Fill a basin or bathtub with hot water. The water temperature should be at least 40–50°C, and for cotton or linen even 60–70°C is recommended. That’s the classic advice. I usually say: use the same water temperature you plan to wash the finished garment at – that’s enough. So, if you’ll wash a blouse at 40°C, there’s no need to prewash the fabric at 80°C.
Adding a colour fixative:
If the fabric is coloured, you can add a few drops of vinegar or a bit of salt to the water to help set the dye.
Soaking:
Immerse the fabric completely in the water and press it down with a wooden spoon or similar utensil to make sure it’s fully soaked. I usually fold the fabric and turn it in the water until it’s wet through all layers. Never bunch it up when submerging, because that will make it harder to handle after prewashing.
Waiting:
Leave the fabric in the soaking water until it has completely cooled down.
Instead of spinning:
Gently press the water out of the fabric – possibly in several steps – but don’t wring it! This requires patience, because if you twist and crease wet fabric, you’ll cause wrinkles that might be impossible to remove, even with steaming.
Drying:
Lay the fabric out flat with as few creases as possible and let it dry completely. Some fabrics can be hung to dry; others must be laid flat. Pay attention so that the fabric doesn’t stretch. Even when hanging, I never let the whole weight of the fabric hang from one rod; I loop it across several rods to distribute the weight evenly.
Fabrics that need to be laid flat can be placed loosely on top of the drying rack so air can circulate underneath – they’ll dry faster. It’s practical to place the drying rack in the bathroom or outdoors where dripping water won’t be a problem.
Ironing:
After drying, iron the fabric, preferably on the wrong side.
Synthetics:
Fabrics made of 100% synthetic fibres don’t need prewashing, as they don’t shrink. Still, I usually wash them once anyway.
Using the washing machine:
Avoid prewashing in a washing machine, as detergent and the mechanical action can damage the fabric, leaving it with a marble-like, worn appearance.
Cotton
Usually shrinks by 2–5%.
Drying: preferably flat or on a hanger; avoid wringing.
Linen
Can shrink significantly (up to 10%).
Drying: flat or on a hanger, as it wrinkles easily.
Tip: steam iron while slightly damp – it smooths out and keeps its shape.
Viscose
Very delicate: easily stretches and shrinks (5–10%).
Drying: flat, as it can stretch under its own weight.
Wool
Can shrink and felt.
Instead of washing, it’s better to prepare it with steaming.
Drying: never wring – dry flat between towels.
Tip: before cutting, lay a damp sheet over it and steam through.
Silk
Prefer dry cleaning or gentle hand washing in very lukewarm water.
Drying: flat, in the shade.
Tip: if in doubt, leave it unwashed and have the finished garment cleaned professionally.
Polyester and synthetic fabrics
Generally don’t shrink, so prewashing is less critical.
Tip: use a little fabric softener to reduce static build-up.
Out of habit, I still prewash these too.
Prewashing fabrics may seem like extra work, but in the long run it saves you a lot of frustration. The finished piece will keep its shape and size, and the fabric will feel much softer and nicer to work with. So, whenever you buy new fabric, take a bit of time to prepare it properly before cutting – that way sewing will stay a true pleasure! ✂️✨
👉 How do you prepare your fabrics before sewing? Share your tips in the comments – let’s exchange our tricks and experiences!