Single jersey fabric development: from yarn to tested fabric

A step-by-step development guide for cotton, CVC and Lycra single jersey: yarn, gauge, stitch length, dyeing and finishing, hitting finished GSM and width, and testing, built on our real development records.

Single jersey is the first fabric most development engineers learn, and it is still the fabric they develop most often. T-shirts, polo bodies, sleepwear, baby wear and fashion tops all start from it. It looks simple: one set of needles, one yarn per feeder, one plain loop. But a buyer’s request for “160 GSM, 100% cotton, 170 cm open width, shrinkage within ±5%” hides many decisions. Which count? Which gauge? What stitch length? How much will the fabric gain or lose in dyeing, stenter and compactor? This guide walks through the whole route, from yarn to a tested and approved fabric, and builds it on real figures from our development records: about 5,100 single jersey and 1,650 Lycra single jersey entries in our fabric register, plus 45 single jersey test reports from our lab reports. Where a value comes from general practice rather than our records, it is marked as typical.

What single jersey is

Structure: face loops, back loops, wales and courses

Single jersey is a weft knitted fabric made on one bed of needles, usually a circular machine with a single cylinder. Every needle knits every course, and every loop is pulled through the previous loop in the same direction. That one rule gives the fabric two different sides.

• Technical face. You see the two legs of each loop. They form a column of small V shapes. A vertical column of loops is called a wale.
• Technical back. You see the loop heads and the sinker loops (the yarn that joins one loop to the next). They form rows of small arcs. A horizontal row of loops is called a course.

The amount of yarn in one complete loop (head, two legs and the sinker loop) is the stitch length, also called loop length. It is the single most important knitting setting, because it decides how open or tight the fabric is and, together with the yarn count, how heavy it is.

Properties you must design around

• Edge curling. Because all loops pull the same way, the cut edges roll: towards the technical back at the top and bottom, towards the technical face at the sides. This matters in slitting, stenter feeding and garment cutting.
• Spirality. In tubular single jersey the wales do not stay vertical. They lean at an angle, and after washing the side seam of a garment can twist to the front. The main causes are residual twist in the yarn and the number of feeders on the machine. Finishing can hide it for a while, but a wash brings it back.
• Extensibility. Single jersey stretches easily in width and less in length. It also shrinks, mainly in length, when it relaxes after finishing.
• Ladder and unravelling. A broken loop can run along the wale. It can also be unravelled from the end knitted last.

Where it is used, and its common variants

Plain single jersey is the base for basic tees, inner wear, nightwear and lining. The main variants are:

• Lycra single jersey. Cotton plated with a bare elastane filament, usually 20 or 40 denier, for stretch and recovery. It needs heat setting.
• Slub single jersey. Knitted with slub yarn (thick and thin places) for a textured look. GSM and shade can vary more along the length.
• Melange single jersey. Knitted with yarn spun from a blend of dyed and undyed fibre, so the fabric is usually only scoured or washed, not dyed.
• Yarn-dyed stripe. Knitted from dyed yarns on a machine with stripe feeders. Shrinkage and fastness depend on the yarn dyeing, and the fabric is usually finished without piece dyeing.

This guide concentrates on piece-dyed 100% cotton, CVC and Lycra single jersey, because that is where most development work happens.

Development inputs

Read the buyer’s request carefully

Before any yarn is chosen, write down every requirement from the buyer in one place. A typical request contains:

• Finished GSM with a tolerance, often ±5%.
• Finished width (open width in cm or inches) or tubular dia.
• Composition, such as 100% cotton, 60/40 CVC or 95/5 cotton/elastane, and sometimes organic or recycled content.
• Yarn quality where named: combed or carded, ring or compact.
• Shade and the light source for approval.
• Wash care, which decides the shrinkage and fastness test conditions (wash temperature, tumble dry or line dry).
• Test requirements: dimensional stability, spirality, bursting strength, pilling, colour fastness, pH and fibre content.

If any of these is missing, ask. A request that says only “160 GSM jersey” will be judged later against the buyer’s standard test manual, so you need to know which manual applies.

Choosing the yarn

Count. The count sets the weight range you can reach. In our development records the usual pairing runs from 16/1 Ne for heavy jersey around 240 GSM down to 34/1 for light jersey around 135 GSM. The table in the knitting section shows the full ladder.

Combed, carded or organic. Combed yarn has fewer short fibres and neps, so it gives a cleaner surface, better pilling and more even dyeing. Carded yarn is cheaper but hairier. Organic cotton is a fibre origin claim, not a spinning quality. It can be combed or carded, and it needs certification paperwork through the whole chain.

Ring, compact or open-end. Ring-spun yarn is the standard for jersey. Compact yarn is a ring yarn with less hairiness, which helps pilling and gives a cleaner face. Open-end (rotor) yarn is bulkier and more even but feels harsher and is weaker. It is used for cheaper, heavier jersey and some melange.

Twist and spirality. Yarn twist is the most important yarn factor for spirality. A single yarn wants to untwist. In a knitted loop, that torque leans the loop, and the wale follows. Knitting yarns are therefore spun with lower twist than weaving yarns; a twist multiplier (αe) of roughly 3.2 to 3.8 is typical for cotton knitting yarn, and it varies by spinner and end use. Lower twist reduces spirality but weakens the yarn and can raise pilling. Other routes to control spirality are a finer gauge or tighter fabric, fewer feeders, compact yarn, and for Lycra fabric the heat setting that locks the structure.

Common mistake: changing the yarn supplier between the trial and bulk without telling the knitting section. Two lots of the same nominal count can differ in twist and actual count, and that changes GSM and spirality.

Knitting

Gauge and diameter

Gauge is the number of needles per inch of the cylinder. A finer count needs a finer gauge, because a fine yarn in a coarse gauge makes an open, unstable fabric, and a coarse yarn in a fine gauge breaks needles and makes a board-like fabric. In our records the usual pairing is 16G for 16/1, 20G for 18/1 and 20/1, 24G for 22/1 to 26/1, and 28G for 28/1 to 34/1.

Diameter decides the width. The total number of needles is the diameter in inches × π × gauge. After finishing, the open width equals those needles divided by the wales per cm in the finished fabric. In our register the most used diameter is 30 inch, then 34 and 36 inch, with some 28 and 32 inch. A larger diameter gives a wider fabric for the same gauge and construction.

Worked example. A 30 inch, 24 gauge machine has 30 × 3.1416 × 24 = about 2,262 needles. If the finished fabric has 13 wales per cm, the open width is about 2,262 ÷ 13 = 174 cm. If finishing makes the fabric narrower, so it has 14 wales per cm, the width falls to about 162 cm. The same machine can give quite different widths depending on how the fabric is finished.

Stitch length, count and GSM

The weight of a knitted fabric is simply the weight of yarn in one square metre. That gives a clean formula:

GSM = (courses per cm × wales per cm × stitch length in mm × yarn tex) ÷ 100, where tex = 590.5 ÷ Ne count.

Stitch length and count are set by you. Courses and wales per cm are not set directly. They come from the stitch length and from how the fabric relaxes in dyeing and finishing. A longer stitch length puts more yarn into each loop but also makes the loops bigger, so there are fewer loops per square centimetre. In practice, for the same count, a longer stitch length gives a lighter, more open fabric, and a shorter one gives a heavier, tighter fabric. A finer count, with less mass per metre, gives a lighter fabric. You can try combinations with the knit GSM from stitch length calculator or the general GSM calculator.

A useful check is the tightness factor, √tex ÷ stitch length in mm. For the medians in our records it works out at about 1.6 to 1.9 (16 to 19 if you put stitch length in cm, the form most textbooks use), so a new construction far outside that band is worth questioning before you knit.

Count, gauge, stitch length and GSM from our records

The table below shows the median settings for 100% cotton single yarn single jersey in our development records. Stitch length is in mm per loop, with the interquartile range (the middle half of entries) in brackets. Required GSM is what the buyer asked for; finished dia is the open width after finishing.

The pattern is clear. As the count gets finer, the gauge goes up, the stitch length goes down and the required GSM falls. The stitch length band is narrow: for 24/1 the middle half of all entries sits at 2.80 mm. That tells you the floor has settled on a standard for each count, and a new development should start from these values, not from a blank sheet.

Lycra plating

In Lycra single jersey a bare elastane filament is fed together with the cotton yarn into the same needle hook. The feeder guides place the cotton on the outside (face) and the elastane on the inside (back), so the elastane is hidden. This is called plating.

• Full feed. Elastane is fed at every feeder, so every course has elastane. This gives the most stretch and recovery and a heavier, more compact fabric.
• Alternate feed (half feed). Elastane is fed at every second feeder. Stretch and power are lower, the fabric is lighter and cheaper, and the risk of curling and uneven stretch is a little higher.
• Elastane denier. 20 denier and 40 denier are common in our records, for example 34/1 cotton with 20 denier, and 40/1 cotton with 20 or 40 denier. Higher denier gives more power and weight.
• Feed tension. Elastane is fed under a controlled draft from a positive feeder. Uneven tension between feeders shows as bars or stripes across the fabric and as uneven GSM. Record the draft or tension setting on every trial.

The Lycra single jersey entries in our records all use a 2.90 mm median stitch length, longer than plain cotton jersey of similar weight, because the elastane pulls the loops together after knitting and the fabric becomes much more compact than it looks on the machine.

Machine settings to record

A trial that is not recorded cannot be repeated. For every knitting trial, write down:

• Machine number, diameter, gauge and number of feeders.
• Yarn count, type, lot and supplier for each feeder.
• Stitch length, measured on the greige fabric, not only the cam setting.
• Yarn input tension, and for Lycra the elastane draft or tension.
• Cam or stitch setting and machine speed.
• Take-down tension or take-down speed.
• Greige tubular dia, greige GSM and roll weight.

Greige inspection

Check the greige roll before it goes to the dye house. Inspect for holes, needle lines, drop stitches, elastane breaks, oil stains and barre. Measure the greige GSM and the tubular dia, ideally after the roll has rested and relaxed for some hours. Greige GSM is usually lower than finished GSM, because the fabric shrinks in length and sometimes in width during wet processing. How much depends on the count, the stitch length and the finishing route, and that is why you must record it against the finished result.

Dyeing and finishing route

All single jersey in our register is finished on an open-width route with stenter and compactor. The full route is shown below with typical parameter ranges. Exact values depend on the dye supplier, the machine and the shade, so treat them as a starting point. A shorter overview is in the single jersey dyeing and finishing flowchart, and the full wet processes are in 100% cotton knit dyeing process, cotton elastane (Lycra) knit dyeing process and CVC fabric dyeing process.

• Heat setting (Lycra only). The greige fabric is set on the stenter, typically around 185 to 195°C for 30 to 60 seconds, at the target width. This fixes the elastane so the fabric holds its width and does not curl or lose shape in dyeing. In our records almost all Lycra single jersey entries, about 98 to 100%, are heat-set.
• Scouring and bleaching. Caustic soda, hydrogen peroxide, a stabiliser and a wetting agent, typically 95 to 98°C for 45 to 60 minutes. Then hot rinse and neutralise, and remove leftover peroxide before dyeing.
• Enzyme (bio-polishing), if required. Acid cellulase at about pH 4.5 to 5.5 and 50 to 60°C for 45 to 60 minutes, then deactivate. It removes surface fibres and improves pilling and handfeel, but it also loses some weight and strength.
• Reactive dyeing. Salt and alkali dosed in steps, fixation typically at 60°C for most vinyl sulphone and bifunctional dyes and up to 80°C for hotter types, at about pH 10.5 to 11. See how reactive dyes work and, for patchy results, level dyeing and uneven shades. CVC adds a disperse dyeing step for the polyester part.
• Wash-off. Rinse, neutralise and soap near the boil to remove unfixed dye. A poor wash-off shows later as poor wet rubbing and staining.
• Softener. Usually at 30 to 40°C and pH about 5 to 6 for 15 to 20 minutes. The type and amount affect handfeel, absorbency and sometimes shade.
• Slitting and de-watering. The tube is slit open along a marked needle line and squeezed or hydro-extracted to remove water evenly.
• Stenter. Drying and width setting, typically 130 to 160°C for cotton, with overfeed to push length into the fabric. Lycra fabric should not be dried hotter than its heat set. Stretching the width here makes the fabric lighter.
• Compactor. Steam and overfeed compress the fabric in length to reduce length shrinkage and set the final GSM and width.
• Final inspection. Measure GSM, width, shrinkage and spirality, and check shade and faults before the fabric is released.

Hitting finished GSM and width

What our records show

The most useful finding in our development records is that single jersey tends to finish light. For 100% cotton single jersey, the median finished GSM is 5% below the required GSM. Only about half of the entries finish within ±5% of the required GSM, and almost all of the rest finish more than 5% below it. Very few finish heavy.

Why the fabric finishes light

• Relaxation is not complete. The fabric leaves the compactor with some length still stretched in. When the dye house washes a sample, it relaxes and shrinks in length, and the GSM goes up. In our records GSM rises a median of about 8% after the wash test.
• Stenter stretch. Running the stenter wide to meet the width target pulls the fabric thinner. Each extra centimetre of width comes from GSM.
• Compactor settings. Too little overfeed on the compactor leaves length in the fabric, which keeps GSM low and shrinkage high.
• Greige planned at the edge. If the stitch length chosen in knitting only just reaches the target with perfect finishing, normal variation in the dye house pushes half the lots below it.

Look at the after-wash column. For most counts the GSM after the wash test lands close to, or above, the required GSM. In other words, the fabric has the right amount of yarn in it. It simply has not relaxed enough in finishing. The fix is usually better relaxation and compaction, not a heavier construction.

Shrinkage by count

Length shrinkage grows as the count gets finer: about -4% for 16/1 and 18/1, -5% for 20/1 to 24/1, -6% for 26/1 and 28/1, and -7% for 30/1 to 34/1. Width shrinkage stays about -2% across almost the whole range; 16/1 is the exception at -4%. Finer, lighter fabrics are knitted with a shorter stitch length and are stretched more in length on the way through finishing, so they have more to give back when washed. Plan more compaction for fine counts. You can estimate the effect of a planned shrinkage on cut size with the fabric shrinkage calculator, and a fibre-by-fibre comparison is in our knit GSM and shrinkage by fibre study.

CVC versus cotton

CVC and PC single jersey behave better. At 24/1 and 30/1 the median finished GSM equals the required GSM, and at 20/1 it is 195 against 200. Length shrinkage is lower too: -3.5% at 20/1, -3% at 24/1 and -4% at 30/1, compared with -5% to -7% for cotton of the same count. The polyester part does not swell and relax in water like cotton, and it holds its dimensions after heat in the stenter.

Lycra single jersey

Lycra single jersey finishes lighter than required in our records, by more than plain cotton: 166 against 180 GSM for 34/1 with elastane on 28G, and 182 against 200 for 30/1 with elastane on 28G. After the wash test it rises above the requirement, for example to 185 and 206 GSM. Length shrinkage is -5% to -8%. The elastane pulls the fabric together hard when it is free to relax, so the heat setting width, stenter width and compaction must be planned together.

How to plan greige GSM and dia

1. Start from the record table for the count: gauge, stitch length and the usual finished dia.
2. Look at the finished GSM, not only the required GSM, for that count. If the median finishes 5% light, plan for it.
3. Knit a short trial, record greige GSM and dia, and send it through the full bulk route, not a lab shortcut.
4. Measure finished GSM and dia and the GSM after the wash test. If finished GSM is low but after-wash GSM is right, improve relaxation and compaction. If both are low, shorten the stitch length slightly or use a coarser count.
5. Write the greige to finished ratio for GSM and dia on the record sheet so the next order starts closer.

Common mistake: correcting a light finished GSM by shortening the stitch length when the after-wash GSM is already on target. The fabric becomes heavier after the customer’s first wash, and the length shrinkage problem stays.

Testing the developed fabric

Every development must pass the buyer’s tests before approval. The typical tests and our lab results for single jersey are below. The 45 single jersey reports that reached our desk include many that were sent because of a problem, so their fail rates are higher than in overall production. Use them to see where the risk lies, not as a production average.

Three points stand out. First, GSM is the most failed test on single jersey, 21 fails in 44 results, which matches what the register shows about finishing light. Second, shrinkage fails in 15 of 60 results, and the range is wide: the median is a modest -2.3% in length, but individual results run from -9.2% to +2.3%. Third, spirality did not fail at all, with a median of 0.0% and a maximum of 3.0% after washing, so the yarn and knitting choices in the table above keep it under control.

Wet rubbing is the colour problem to watch. Medium and dark shades often rate 3 or 2–3, which is close to common buyer limits. Good wash-off, the right softener and avoiding over-dyeing help. The testing methods and fixes are covered in these guides:

• How to test shrinkage of knit fabric and shrinkage test fail: causes and remedies
• How to test spirality of knit fabric
• How to test GSM of knit fabric and GSM test fail: causes and remedies
• Wet rubbing fastness fail: causes and remedies

Worked example. A 28/1 cotton jersey is required at 160 GSM. Our register median for this count finishes at 152 GSM, which is exactly 5% light, at the edge of a ±5% tolerance. After the dye-house wash test the median is 165 GSM. The fabric has enough yarn; it is leaving the compactor with length still stretched in. Before changing the 2.70 mm stitch length, try more compactor overfeed and less stenter width stretch, then re-test both finished GSM and length shrinkage.

Development record sheet and troubleshooting

The development loop below is how a request becomes an approved fabric. Each pass round the loop must leave a record, so that the next trial changes one thing on purpose and the result can be traced.

Record sheet template

Use one sheet per trial. Keep the request values and the actual values side by side.

Troubleshooting

When a trial misses the target, start with the most likely cause and change one setting at a time.

Single jersey development rewards patience and good records more than clever tricks. Start from proven count, gauge and stitch length pairs, expect cotton to finish slightly light and to shrink more in finer counts, plan compaction for it, and test the fabric the way the buyer will. Every trial you record makes the next one shorter.

Questions

What stitch length is used for 24/1 cotton single jersey?

In our development records the median is 2.80 mm on a 24 gauge machine, for a required GSM of 180. Use it as a starting point and confirm with a trial.

Why does single jersey finish below the required GSM?

Mostly because the fabric leaves the compactor with length still stretched in, and stenter width stretch makes it thinner. In our records cotton single jersey finishes a median 5% light, and GSM rises about 8% after the wash test.

How much does cotton single jersey shrink?

In our records length shrinkage grows from about -4% for 16/1 and 18/1 to about -7% for 30/1 to 34/1, while width stays about -2%. CVC shrinks less in length than cotton of the same count.

Does Lycra single jersey need heat setting?

Yes. Heat setting fixes the elastane so the fabric holds its width and shape in wet processing. Almost all Lycra single jersey in our records is heat-set.

What causes spirality in single jersey?

Mainly residual twist in the yarn, plus the number of feeders and a loose construction. Lower-twist or compact yarn and a tighter fabric reduce it; in our lab reports spirality did not fail in 51 results.

Kamrul Islam

Textile engineer with 14+ years in dyeing and fabric development. He writes every guide on Dyeing Solution from real production work. Full profile