Interlock is a double-knit fabric: in effect, two 1x1 rib fabrics knitted into each other so that the back loops of one are hidden between the loops of the other. It is made on circular machines with a cylinder and a dial using interlock needle arrangement, or on flat machines.
How it looks and feels#
- Both faces look like the face of single jersey: smooth columns of V-shaped wales.
- Thick and firm compared with jersey of the same yarn.
- Soft, smooth surface that prints well.
- Does not curl at the edges.
- Less stretch than rib or jersey, but more stable.
Properties compared#
| Property | Single jersey | 1x1 rib | Interlock |
|---|---|---|---|
| Faces | Different | Similar | Same (both smooth) |
| Curling | Yes | No | No |
| Widthwise stretch | Good | Very high | Moderate |
| Stability | Lower | Moderate | High |
| Laddering | Runs from either end | Runs from the end knitted last | Runs mainly from the end knitted last |
| Typical GSM | 110 to 260 | 180 to 260 | 200 to 280 |
Where interlock is used#
- Baby wear and children's wear: soft on both sides, stable, comfortable.
- Polo shirts and tops: a smooth alternative to pique.
- Sportswear and school wear: especially in polyester or blends, often printed.
- Underwear and nightwear: comfortable and opaque.
Cutting and sewing#
- Interlock is easier to cut than jersey because it lies flat and holds its shape.
- It still needs relaxation before spreading.
- Use ball point needles and extensible stitches, as for other knits.
- Its thickness can make seam crossings bulky; check needle size and machine feeding.
Finishing notes#
Because interlock is thick and dense, dyeing and finishing must penetrate both layers evenly. Uneven dyeing, compaction problems and pilling on some blends are the typical finishing concerns. Pilling performance depends heavily on yarn quality and finish; see pilling testing.
Specifying interlock#
- Composition and yarn count
- Finished GSM with tolerance
- Finished width (open or tubular)
- Shrinkage limits after the specified wash test
- Pilling and colorfastness requirements
- Finish (soft, peach, anti-pill)
Compare with single jersey, rib and pique.
Interlock vs single jersey for the same garment#
Merchandisers often choose between interlock and single jersey for the same product, such as a children's T-shirt or a school polo. The practical differences:
| Question | Single jersey | Interlock |
|---|---|---|
| Fabric cost per garment | Lower: lighter fabric, fewer kg per dozen | Higher: heavier and more yarn per m² |
| Opacity | Can be see-through in light colors | Opaque |
| Edge handling in cutting | Curling slows spreading and sewing | Lies flat, easier to handle |
| Shape after washing | More prone to spirality | Stable, twists less |
| Print surface | Good | Very good: smooth on both sides |
Because interlock is heavier, consumption in kg per dozen rises even when the panel areas are the same. Recalculate consumption with the interlock GSM rather than scaling from a jersey quote. See fabric consumption.
Frequently asked questions#
Is interlock a double knit? Yes. It is knitted with two sets of needles, which is why both faces look the same and the fabric is thicker than single jersey.
Does interlock ladder? It is much less prone to running than single jersey. It can still unravel from the end knitted last if the yarn is broken and pulled.
Why is my interlock narrower than expected? Interlock relaxes and narrows after knitting and wet processing. Agree the finished width with the knitter and check it at fabric inspection, not the greige width.
Can I use the knit GSM estimate for interlock? Not the single jersey loop-length method. Weigh a cut sample instead, as described in fabric GSM.