Should You Pre-Wash Fabric Before Sewing?

Ask a room of sewists whether to pre-wash fabric and you will get a lively argument. Quilters disagree among themselves; dressmakers mostly pre-wash; upholsterers mostly do not. The disagreement is not really about right and wrong, because pre-washing solves some problems and creates others. This guide sets out what pre-washing does, which fabrics benefit and which do not, how to do it without wrecking the fabric, and how to use a small test piece and the site's Fabric Shrinkage Calculator to decide on evidence rather than habit.

What pre-washing does

• Takes out relaxation shrinkage before you cut, so the finished item keeps its size when it is first washed.
• Removes excess dye, so colours are less likely to bleed onto lighter fabrics later.
• Washes out finishes and sizing: starches, softeners, and residual chemicals from manufacturing. That can make fabric softer and kinder to sensitive skin, and some people pre-wash for that reason alone.
• Shows you how the fabric behaves: whether it frays badly, creases, pills, or changes texture.

It also has costs: it takes time, it can make fabric harder to cut accurately because the crisp finish has gone, it can distort the grain, and for some fabrics it changes the look you bought them for.

Fabrics that usually benefit

• Cotton for garments, bedding and anything that will be washed often, especially if it is not labelled pre-shrunk.
• Linen, which often shrinks noticeably and softens a great deal with washing.
• Viscose, rayon and other regenerated cellulose fabrics, which can shrink and change hand.
• Cotton and linen jersey and other knits that will be machine-washed.
• Strongly coloured fabrics that will be combined with light ones.
• Fabrics for babies' and children's clothing and bedding, to remove finishing residues.

Fabrics to think twice about

• Dry-clean-only fabrics, many wool suitings, silks with special finishes, and structured fabrics such as some taffetas and brocades. Washing them can ruin texture, lustre or structure.
• Coated, laminated and bonded fabrics: oilcloth, PU-coated cottons, waterproof laminates, faux leather.
• Fabrics whose finish is the point: glazed chintz, polished cotton, crisp organdy.
• Items that will never be washed, such as some wall hangings, framed textiles, and upholstery that will only be spot-cleaned.
• Quilting cotton for a quilt you want to crinkle: some quilters deliberately skip pre-washing so the finished quilt shrinks slightly and takes on a puckered, antique look.

Wool deserves its own note. Wool can felt if washed warm with agitation, shrinking dramatically and permanently. Tailors traditionally pre-shrink wool with steam rather than washing it. If you do wash wool, use the gentle, cool method the care label specifies.

Test before you decide

You do not need to pre-wash a whole length to find out whether it matters. Cut a test piece, mark a measured length in both directions, wash and dry it exactly as you will treat the finished item, and measure again. For example:

• a 100 cm mark that comes back at 97 cm is 3% shrinkage;
• a 100 cm mark that comes back at 95 cm is 5% shrinkage.

Quilters often have only a fat quarter or a 25 cm strip. That still works: a 25 cm mark that comes back at 24.25 cm is also 3% in the calculator. Smaller marks are harder to measure precisely, so read to the millimetre and test in a couple of places.

Then decide. A cotton that shrinks under about 1% in your wash hardly needs pre-washing for size; one that shrinks several percent does. The guide to measuring shrinkage with a wash test covers the method in full.

How to pre-wash without ruining the fabric

1. Finish the cut edges. Zigzag, overlock or pink the raw ends, or the washing machine will unravel long tangles of thread, especially from loosely woven fabrics. Some people fold the length and stitch the ends together into a loose tube.
2. Wash as the finished item will be washed. If the finished shirt will go in at 40°C and into the dryer, that is how to pre-wash. Pre-washing more gently than you will wash the finished item leaves shrinkage in the fabric.
3. Wash dark and strong colours separately the first time, or with a colour-catcher sheet, and check whether the water or a white offcut picks up dye.
4. Dry the same way the finished item will be dried. Tumble drying usually shrinks more than line drying.
5. Press and straighten the grain. Washing can skew the weave. Pull the fabric gently on the bias to square it, and press before cutting.

How much fabric to buy if you pre-wash

Pre-washing shrinks the whole length, so buy enough to end up with what the project needs. Work out the length you need with the Fabric Yardage Calculator, then use the shrinkage calculator's pre-cut mode with your test result to find the length to buy. For a project needing 2 m after washing, a fabric that shrinks 5% needs about 2.11 m before washing. The guide to buying extra fabric for shrinkage goes through the full calculation, including width.

If you do not pre-wash

Not pre-washing is a reasonable choice when the fabric is stable, the item will never be washed, or you want the finish. But be consistent within a project: mixing pre-washed and unwashed fabrics of different types in one item is the recipe for puckered seams and uneven quilts. And if the fabric does shrink, cut larger by the measured amount and accept that the first wash will settle it.

The quilting question

Quilters argue about pre-washing more than anyone, and both sides have a point. Pre-washing quilting cotton removes excess dye, which matters in a quilt that pairs deep reds or navies with white, and it takes out shrinkage, so the finished quilt keeps its measured size. Skipping it keeps the crisp finish that makes small pieces easier to cut and piece accurately, and the slight shrinkage of the whole quilt after its first wash gives the soft, crinkled texture many people like. Precut bundles such as charm squares and jelly rolls are usually not pre-washed at all, because small pieces fray and distort in the machine. Whichever you choose, treat every fabric in the quilt the same way, and test any fabric whose colour you are unsure of. A dye test takes a few minutes: wet a corner, press it against a white scrap with a hot iron, and see whether colour transfers.

Pre-washing interfacing and notions

Fabric is not the only component that can shrink. Some woven and knit fusible interfacings shrink when pressed or washed, which can bubble the outer fabric; some makers pre-shrink them by soaking in warm water and drying flat, following the manufacturer's guidance. Cotton tapes, ribbons, piping cord and zip tapes can also shrink; pre-wash them with the fabric if the finished item will be washed.

Safety and care

Some fabrics sold for children's nightwear or furnishings carry flame-retardant finishes, and in some countries furnishings and children's nightwear must meet flammability rules. Washing can reduce some finishes; follow the care instructions supplied with such fabrics, and if a finished item must meet a flammability requirement, make sure the way you treat the fabric does not compromise it.

Summary

Pre-wash when the finished item will be washed and the fabric shrinks, bleeds, or carries finishes you do not want. Skip it for dry-clean-only, coated and finish-dependent fabrics, and for items that will never be washed. If you are unsure, a 15-minute test on an offcut, read through the shrinkage calculator, settles it.