What Is Rib Knit?

How is rib knit made?

Rib knit is made on two sets of needles, so that some columns of loops (wales) form on the face of the fabric and the columns between them form on the back. On a circular machine the two needle beds are the cylinder and the dial: cylinder needles knit a face wale and dial needles knit a back wale. Flat machines with two needle beds set in a “V” knit the chunkier, heavier-gauge ribs used on a sweater.

Because it needs two needle beds, rib is classed as a double knit, like interlock and Ponte di Roma. How the needles are spaced between dial and cylinder, called rib gaiting, sets the pattern.

1×1 and 2×2 rib

Rib is named by its repeat. In 1×1 rib the loops alternate one by one between dial and cylinder needles. In 2×2 rib, two stitches on the cylinder alternate with two on the dial. The numbers describe the structure, not the fibre.

A documented step: ribbed stockings by machine

One documented milestone in rib’s history is mechanical: in 1759 Jedediah Strutt and his brother-in-law William Woolatt patented an attachment for the stocking frame that could knit ribbed stockings. According to the Science Museum Group, the invention came from one of Woolatt’s employees.

How is rib knit different from jersey and interlock?

Rib looks the same on both sides and stretches about twice as far across its width as single jersey; interlock also looks the same on both sides but is more rigid and stable than rib.

For the single knit in the first column, see jersey fabric. Interlock repeats over two feeds of the machine, while a 1×1 rib is complete after one. Corduroy, despite its raised ribs, is a woven cloth, not a knit.

What are the properties of rib knit?

Rib knit is stretchy across its width, looks the same on both faces, and is heavier and more durable than a plain knit. Britannica describes rib knits as “fairly heavy”, with good elasticity, and more durable than plain knits.

• Crosswise stretch. Pulled across its width, rib opens like an accordion as the back wales come into view. Pulled lengthwise, the back wales slide behind the face wales and the fabric narrows.
• Weight and cost. A double knit is two fabrics linked together in knitting. It uses more yarn than a single knit, which adds weight and cost.
• Edges. Double knits curl less than single knits. Correctly knitted rib does not curl, but it can run or unravel from the last knit.
• Uses. Basic ribs are used for dresses and sweaters and for the trim of neck collars, wrists and waistbands. Flat machines, most of which are double-knit V-beds, also knit flat trims such as the collars of a polo shirt.

How is rib knit graded or measured?

Rib knit is described rather than graded: by its rib repeat (1×1, 2×2), the gauge of the machine, the fibre content and the weight.

Gauge is the number of needle slots (tricks) per inch of the machine: a cylinder with 18 needles per inch is 18 gauge. CottonWorks, the education site of Cotton Incorporated, puts standard knits at 20–44 gauge, with ultra-fine knits reaching 60 gauge. For cotton, 8–28 gauge is common, with finer gauges up to 44. Ribs range from very fine to very heavy and chunky, depending on the machine.

How does rib knit appear on a clothing label?

Rib is a structure, not a fibre, so the label lists the fibres it is knitted from. Under US law, most clothing needs a label giving the fibre content by generic name and percentage of weight, the country of origin, and the identity of the manufacturer or another business that markets or handles the product.

• The 5% line. In general, only fibres making up 5% or more of the weight may be named; smaller amounts are listed as “other fiber” unless they have a definite functional significance at that amount. The FTC’s own example is 4% spandex added for elasticity, which may be named. See Lycra (spandex) for that fibre.
• Wool is the exception under the US Wool Rules. Wool or recycled wool must be disclosed by name and percentage, even under 5%.
• Tolerance. US fibre percentages may be off by up to 3%. No tolerance applies when the label says the product is made of a single fibre, such as “100% cotton”.

How do you tell good rib knit from poor rib knit?

Good rib knit looks the same on both sides, stretches well across its width and closes back up, lies flat at its edges, and comes with a clear fibre and care label.

Five checks in the shop

1. Turn it over. True rib looks the same on the back as on the face. If the back shows rows of loops (crowns) unlike the face, it is not rib: that is how the back of single jersey looks.
2. Count the ribs. Single raised columns alternating with single sunken ones are 1×1 rib; pairs are 2×2.
3. Stretch it across. Pull a cuff or hem sideways: it should open like an accordion and show the back wales. Let go and it should close again, showing the good elasticity Britannica credits rib with.
4. Look at the edges. Rib that is knit correctly lies flat. A curling cut edge points to a single knit, and loose loops at an edge are where rib can run.
5. Read the fibre line. Spandex under 5% may be named only because it has a function, such as elasticity. Minor fibres without one appear as “other fiber”.

Red flags

• A neckband or cuff that stays stretched out after you release it: the elasticity has gone.
• An edge that rolls up on a garment sold as rib.
• No permanent care label on a garment (hats are exempt in the US, so a beanie may lawfully have none).

How do you care for rib knit?

Care for rib knit by following its permanent care label, because the right method depends on the fibre and the finish. In the US, clothing labels must give a washing or drycleaning instruction, warn against procedures that would harm the product, and stay legible for the garment’s useful life.

Shrinkage is a known risk. Knits are more open in structure than wovens and more prone to shrinkage. Mills can reduce residual shrinkage with relaxation dryers, compacting or crosslinking agents; without these, there is little or no reduction.

Is rib knit sustainable?

Rib knit is not sustainable or unsustainable in itself: it is a knit structure, so its footprint depends on the fibres on the label. The one structural fact is that a double knit uses more yarn than a single knit, which increases the cost of the fabric.