Why fabric inspection still earns its keep

Every roll of woven cloth carries the history of how it was made: the tension in the warp, the timing of the weft insertion, the humidity drifting through the shed at three in the morning. Most of that story stays hidden. A little of it, though, is written plainly across the face of the fabric, and reading it properly is the job of the inspection line.

Catching a slub or a mispick early changes what happens next. A mender can repair a fault before it becomes a cut-length loss. A grader can price the roll honestly against the customer's specification. A technician can walk back to the loom with something specific to fix, rather than a vague complaint that the cloth "doesn't look right". Inspection isn't about catching people out — it's about giving the mill an accurate picture of what it's producing, roll by roll, shift by shift.

Setting up the inspection frame properly

There's little point hunting for fine faults on a poorly lit frame. The standard arrangement is a viewing surface tilted at roughly 45 degrees to the inspector's line of sight, with diffuse lighting above and below so the fabric is backlit as well as front-lit. Most mills run inspection machines at 15–20 metres per minute; push much faster and the eye simply stops registering small defects, however good the lighting.

Before the first metre, check the essentials:

• Tension — fabric should lie flat without being stretched, otherwise fine warp lines disappear and holes distort.
• Guiding — the cloth must track straight so that a fault's position across the width is repeatable and trustworthy.
• Recording — a marker, tape or digital capture at the fault's exact position, plus a note of whether it is a warp-way or weft-way fault.

An inspector who knows the difference between a fault that runs the length of the piece and one that appears once will save the mill an enormous amount of time downstream.

Warp-way defects: slubs, streaks and broken ends

Warp faults run along the length of the cloth, so they show as continuous or repeating lines. The most familiar is the slub — a thick, soft place where a spun yarn has doubled on itself or a tuft of fibre has been wrapped in. Slubs typically read as short lumps between five and twenty-five millimetres long, and they usually trace back to carding, spinning or a dirty yarn path rather than to the loom.

Other warp-way characters worth knowing:

• Warp streaks — a single end drafting slightly thicker or thinner, appearing as a fine line running the full piece. Often a blend or count variation between bobbins.
• Broken or missing end — the end has stopped feeding, leaving a gap that lets neighbouring ends drift together. If it runs unrepaired, expect a long float until the fault reaches the cloth beam.
• Warp float — an end that should have interlaced but passed over several picks instead. Frequently caused by a lazy heald or a sticky shed.
• Reed marks — regular vertical lines at the reed dents, usually a sign of uneven warp tension or a damaged reed.

Weft-way faults: mispicks, floats and set marks

Weft faults appear across the width, and they tend to be the ones that stop a roll from being sold as first quality. A mispick is the classic: the weft has been inserted twice in the same shed, or a pick is missing altogether, producing a thick or thin band that catches the eye immediately. On a rapier or projectile loom, a mispick often points to a timing issue or a weft brake that is gripping inconsistently.

Weft floats behave in the opposite way — a pick that fails to interlace and rides over the warp for part of the width. Short floats from a broken weft are common and easily mended; long, repeated floats suggest a shedding problem that needs attention at the loom.

Then there's the set mark or starting mark, a visible line where the loom stopped and restarted. It comes from a change in pick density at the restart, and while a single faint mark may be acceptable, repeated set marks across a shift usually mean the loom is stopping too often — often a warp stop motion set too sensitively, or a take-up motion that isn't holding tension steadily during the stop.

Surface and appearance faults

Some faults have nothing to do with interlacement at all. Oil and rust stains from loom parts, contamination from stray fibres of a different colour, and temple marks along the selvedge all reduce the value of an otherwise sound piece. Contamination is particularly frustrating because a single stray coloured fibre can write off a whole panel of fabric destined for a pale shade.

Holes, thin places and selvedge damage deserve immediate attention — they're rarely isolated, and a cluster usually means something mechanical is rubbing or cutting where it shouldn't.

Grading the roll with a point system

Once faults are marked, most mills apply a recognised grading system to turn them into a number. The four-point system is widely used in the UK: a fault is penalised according to its length, with a maximum of four points per fault regardless of size. Points are then normalised against the roll's area, typically expressed per hundred square metres.

In practice, the arithmetic matters less than the consistency of the person doing the marking. Two inspectors looking at the same roll should arrive at the same score, which is why written standards, reference photographs and periodic cross-checks are worth the trouble.

Grading also gives the mill a language for its customers. A roll at twelve points per hundred square metres is a different proposition from one at thirty-five, and both parties should know which they're buying.

Turning defect data into loom-side action

The real value of inspection comes when the defect record travels back to the weaving shed. If mispicks cluster on one loom during the night shift, look at weft tension and humidity. If slubs appear across many looms from the same yarn lot, the conversation belongs with the spinner, not the weaver.

Keep the feedback loop short and specific. A daily summary of fault type, position and loom number, reviewed by the weaving technician and the quality team together, will do more for first-quality yield than any amount of inspecting in isolation. The cloth has already told you what went wrong — inspection is simply how you learn to listen.