Fabric & decoration
Why knit garments shrink, and how factories prevent it
Knit fabric is held under tension while it is knitted, finished and wound onto rolls. When that tension lets go, in the wash or even in storage, the loops pull back and the fabric shrinks. Factories deal with it by testing shrinkage, building an allowance into the pattern, and relaxing the fabric for 24–48 hours before cutting.
Key takeaways
- Knit fabric shrinks because it is stored under tension on the roll and relaxes later.
- Good factories relax the fabric for 24–48 hours, unrolled and tension-free, before cutting.
- Shrinkage test results go into the pattern as an allowance before grading.
- A tension-free spreader stops panels being stretched out of size.
- Shoulder stay tape stops necklines growing, which is a different problem from shrinkage.
The short answer
Knitted fabric is made of interlocking loops. During knitting, dyeing, finishing and rolling, those loops get pulled, mostly lengthways, and the fabric is wound onto rolls while still under that tension. Cut it straight away and you are cutting panels from fabric that is longer than its natural state. Later the loops relax and the garment shrinks.
Three causes
- Residual shrinkage in the fabric, the natural tendency of the knit to shorten after its first washes.
- Tension from the roll. Fabric cut without relaxing keeps shrinking after sewing, even before washing.
- Stretch during spreading and cutting. Fabric pulled tight on the cutting table gives panels that are stretched and spring back smaller.
How we prevent it, stage by stage
1. Test and allow in the pattern
Before production we review the fabric’s shrinkage test report. Knit fabric shrinks after washing, so the measured shrinkage is added to the pattern in advance as an allowance. The patterns are then graded across the size range, taking stretch and recovery in both directions into account.
2. Relax the fabric
This step is the easiest to skip and the most expensive to forget. Rolls are unrolled, shaken out and laid flat for 24–48 hours so the fabric returns to its natural length before it is cut. Fabric that isn’t relaxed gives garments that shrink and distort after washing, or even while they sit in a warehouse.
3. Spread without tension
An automatic tension-free spreader lays the fabric on the table without pulling it. Stripes and checks are pinned by hand so they line up.
4. Protect the neckline
A neckline that grows after washing is a separate problem, caused by the shoulder seam stretching. We sew clear TPU stay tape into the shoulder seams of T-shirts and polos and finish rib collars with a coverstitch, so the neckline keeps its shape.
5. Press gently
Knits are sensitive to heat and pressure. We finish on steam form presses, or with low-temperature steam through a protective mesh, which restores loft and even dimensions without crushing the loops.
What to ask your supplier
- Do you test fabric shrinkage before cutting, and is the result built into the pattern?
- How long is fabric relaxed before cutting?
- Do you use tension-free spreading?
- Is shoulder tape used on T-shirts and polos?
- What size tolerance do you measure to at final inspection?
Final thoughts
Shrinkage is rarely a fabric defect. It is a process problem. A supplier who tests, relaxes, spreads without tension and allows for shrinkage in the pattern will deliver garments that stay in size. Ask the questions above before you place the order, not after the first wash.