Definition
Interlock is a double knit made of two interlocked layers of stitches, smooth on both sides, more stable than jersey and free of curling edges.
Interlock is knitted on two beds of needles, so both of its faces look like the right side of jersey: fine V-shaped columns on each side. Because the two layers hold each other, it lies flat when cut, feels soft and slightly spongy, and is thicker than a jersey made from the same yarn.
Why sewists like it:
- No curling, so it is easy to cut, mark and hem.
- Good body for T-shirts, children's clothes, pajamas, baby clothes and leggings.
- No visible wrong side, handy for reversible pieces or bands folded in half.
Its stretch is moderate, often 25 to 50% across the width and less lengthwise, and pure cotton interlock recovers less well than a blend with elastane.
One quirk: interlock can ladder, or run, from one cut edge, the end that was knitted last. If a gentle pull on an edge starts a run, place the pattern pieces so that edge falls at the hem, where it will be finished, and away from stress points.
Compared with jersey, interlock is heavier, warmer and less drapey; compared with rib knit, it has far less stretch and recovery. Ponte is a heavier double knit in the same family, suited to trousers and structured knit dresses. For sewing methods, see sewing knit fabrics on a regular sewing machine.