Most shrinkage is not the fabric losing size — it is the fabric returning to the size it wanted to be all along. Yarn is held under tension through knitting and finishing, and the first time the fabric meets water and heat, that tension relaxes and the loops pull in. Prevent it and you prevent almost every shrinkage complaint you will ever get.
What are the two kinds of shrinkage?
- Relaxation shrinkage — stored tension releasing. It happens mostly in the first wash, affects cotton knits most, and is entirely predictable. This is the one you can control at the mill.
- Felting shrinkage — fibres physically interlocking and matting together. It affects wool, is driven by heat plus agitation, and is irreversible. Synthetics do not felt.
A cotton jersey that came back 8% shorter relaxed. A wool jumper that came out doll-sized felted. The remedies are different.
What is compacting and how does it help?
Cotton knits are run through a compacting machine that mechanically pushes the loops together before the fabric ever leaves the mill — deliberately doing what the first wash would otherwise do. Properly compacted cotton jersey should come in under 5% residual shrinkage. Fabric that skipped this step can lose 8–10%, which is a full size on a finished garment.
This is a specification you can and should ask for. "Compacted" and "residual shrinkage max 5%, tested to ISO 6330" belong on the purchase order, not in a verbal assurance.
How do you test shrinkage before cutting?
- Cut a 50 × 50 cm square from the roll and mark a precise 40 × 40 cm box inside it with a fine permanent marker.
- Wash it exactly as the finished garment will be washed — same temperature, same cycle, same drying method.
- Dry it flat, let it rest for four hours, then measure the box again in both directions.
- Shrinkage % = (40 − new measurement) ÷ 40 × 100. Do it lengthwise and widthwise separately; they are rarely the same.
Test the actual delivered lot, not a reference swatch. Residual shrinkage varies between dye lots more than composition does.
Which fabrics shrink and which do not?
| Fabric | Composition | Shrinkage risk |
|---|---|---|
| Cotton jersey (süprem) | 100% cotton | High if not compacted |
| Ottoman rib (selanik) | 100% cotton | High; rib structure exaggerates it |
| Three-thread fleece | 65% cotton / 35% polyester | Moderate — polyester limits it |
| Intersoft | 40% cotton / 60% polyester | Low |
| Polar fleece, welsoft, scuba | Polyester based | Very low |
The pattern is simple: the more cotton, the more it moves. Polyester is dimensionally stable because the fibre itself is set with heat during production.
Which care instructions actually prevent shrinkage?
- Wash at 30 °C. Heat is the main driver in every fibre.
- Skip the tumble dryer for cotton knits, or use the lowest setting. Hot tumble drying causes more shrinkage than hot washing does.
- Dry knitwear flat rather than hanging — a wet knit hung on a line stretches lengthwise and then shrinks unevenly.
- Do not iron a garment back to size. It stretches the loops temporarily and they pull in again at the next wash.
What should the manufacturer do?
Build the residual shrinkage into the pattern rather than hoping it will not happen. If tested shrinkage is 4% lengthwise, cut 4% long. Print the care instructions that match the test conditions you used — a garment washed hotter than it was tested for will shrink, and no fabric specification prevents that. Sample lengths for wash testing are available before bulk orders, which start at 50 kg per colour with 2–5 business day delivery.