Knitted Bag Defect Classification: How to Sort Critical, Major, Minor and Cosmetic Faults Before an Inspector Counts Them

What a Defect Class Actually Decides

A defect class decides two things and nothing else: how many of that defect are allowed in the sample, and what happens to the lot when the allowance is exceeded. Everything else that buyers argue about at the dock is downstream of those two decisions. The classification list is therefore not a document about quality, it is a document about consequences, and it should be written with the consequence in mind on every line.

The ISO 2859-1 attribute schemes that most bag programmes run on are indexed by acceptance quality limit, and the usual split is zero for critical, 2.5 for major and 4.0 for minor. On a sample of 200 pieces drawn from a lot of 3,201 to 10,000 at general inspection level II, that means 10 majors or 14 minors will still pass while a single critical defect rejects the lot outright. Three numbers, and the whole commercial outcome of the shipment sits inside them.

The mistake is treating the classification as a shared understanding rather than a written one. A buyer who has never shipped a knitted panel will assume a hole is a hole; a floor that has run knit programmes since 2014 will grade a 1 mm base hole as minor and a 3 mm front-panel hole as major. Both readings are defensible, and only a written trigger settles which one applies to the order.

The Four Classes, and the Number Attached to Each

Four classes is one more than most programmes use and one more is worth having. Critical, major, minor and cosmetic, with an acceptance number attached to the first three and a recording obligation on the fourth. The cosmetic class exists because a knitted surface generates small irregularities that are inherent to the structure, and counting them produces rejections that no rework can fix.

Critical defects are held at zero and the number never moves. They cover anything unsafe or non-compliant: a broken needle fragment left in a panel, a detachable small part on a child's item, a sharp edge on hardware, or a restricted substance finding under ECHA REACH Annex XVII. One occurrence rejects the lot, and there is no appeal to the AQL because the AQL does not apply to this class.

Major defects at 2.5 are anything that makes a bag unsaleable at full price: a hole, a dropped stitch run, a handle that is off-centre beyond tolerance, a shade difference the customer would see across a shelf. Minor defects at 4.0 are workmanship issues a customer notices but would not return over: a thread end, a light press mark, a slight loop irregularity on an inside panel. Cosmetic is recorded only: the slub in a recycled yarn that is part of the yarn's character.

A Defect Catalogue for Knitted Panels

The catalogue below is the working list used on seamless knit bag programmes, with a numeric trigger on every line. The trigger matters more than the class label, because a trigger converts a judgement into a measurement and a measurement can be argued with evidence rather than with opinion. Adopt it as a starting point and adjust the millimetres to the product.

Two lines in that table do most of the work in practice. The shade line is the one that generates the most disputes, because a knitted body and a knitted handle from one dye lot can read as two colours when the structures reflect light differently, and a numeric grey-scale grade of 4 is the only way to settle it without an argument about taste.

Defect Points: Turning a Count into One Number

Some programmes prefer a defect point system over a count, weighting each finding and summing the lot. A common weighting is 100 points for critical, 10 for major, 1 for minor and 0 for cosmetic, with the lot rejected when the total per 100 pieces exceeds 40. The system has one real advantage: it lets a lot with many small faults fail, which a pure count at AQL 4.0 would pass.

It also has a real disadvantage, which is that it hides the critical defect. A weighted total of 38 passes, and a single needle fragment inside it is still a needle fragment, so any point system needs an override rule stating that critical defects reject regardless of the running total. Without that sentence the weighting quietly legalises the one class of defect nobody should be negotiating about.

Where a point system is used, it should be stated on the order acknowledgement alongside the AQL rather than instead of it. Running both is not contradictory: the AQL governs the accept and reject decision on the sample, and the point total is reported as a quality metric for trend tracking across lots, which is where it earns its keep over a season of repeat orders.

Where Knit Defects Come From on the Machine

Classification makes more sense once the fault is traced to its origin, because the origin tells a buyer whether the defect will be sporadic or systematic. A dropped stitch caused by a single broken needle is sporadic and shows up as two or three pieces in a lot. A dropped stitch caused by yarn tension drift across a whole machine is systematic and will appear on every piece knitted after a certain hour.

Yarn tension is the largest single source. On a 3D knitted panel run at gauge E7 or E12, a tension variation of 5 percent across the feeders changes loop length enough to show as a visible course irregularity, and the irregularity reads as a shade band rather than as a stitch fault. That is why a tension-driven fault ends up classified as a shade major and not as a stitch major, and why the fix is on the machine, not at the inspection table.

The second source is take-down, the mechanism that pulls the knitted fabric away from the needles. Take-down set too high stretches the panel on the machine and it relaxes afterwards, producing a dimensional fault that a goods-in inspection sees but cannot classify against a tolerance that was never written. Setting the tolerance before sampling, at 7 working days from tech pack to first sample, is the point at which this is still a one-line change.

Severity by Position: Why Placement Beats Size

Position should be written into the classification explicitly, because the same physical fault is a different commercial fault depending on where it sits. A 3 mm dropped stitch on the front panel of a tote is a major that a retail customer will return. The identical stitch on the inside of the same bag, or on the underside of a base, is a minor that nobody will ever see after the first week of use.

Writing position into the list costs four words per line and it prevents the single most common rejection dispute, which is a buyer rejecting a lot over faults that are technically present and commercially invisible. The convention is to name the zones: outer face, inner face, base, handle and trim. Any fault on an outer face escalates one class; any fault on an inner face de-escalates one class.

There is one exception where position does not help, and that is the handle attachment. A fault there is major regardless of size or visibility, because the handle is the load path and a stitch irregularity in the joinery is a structural question rather than an appearance question. Handle joinery belongs in the load testing programme, measured to ISO 13934-1 on pre-bulk specimens, not in the visual count at all.

Critical Defects That Override Every Number

The critical class is short and it should stay short. Four entries cover almost every bag programme, and a long critical list dilutes it, because an inspector who has to weigh ten critical items against a deadline will start treating some of them as major in practice. Keep it to findings that justify stopping a shipment on the spot and move everything else down a class.

How the List Is Built Before Sampling Starts

The classification list is built during sampling, not during inspection, and there is a practical reason for the sequencing. At 7 working days from tech pack to first sample there is time to knit deliberately faulty pieces, look at them together with the buyer's QC contact, and agree where the trigger sits before anyone has a lot to defend. Once bulk is on the floor, every line becomes a negotiation.

The output of that session should be a one-page list with the reference sample photographs attached, and it should be signed by both sides. Photographs matter more than text here, because a photograph of the accepted 2 mm base hole settles in two seconds a question that a paragraph cannot. Where a buyer cannot attend, a photo sheet with the triggers marked is the next best thing and takes an hour to produce.

After that the list is a controlled document. Any change to a trigger mid-programme invalidates the inspection that preceded it, so the version number belongs on the report, and a change after the first bulk lot should be treated as a specification change with its own sampling round rather than as an amendment to the current one.

Writing the Classification into the Order

Five fields carry the whole thing: the standard and edition, the class limits, the trigger list with version number, the inspection level, and the remedy on rejection. The first four are usually present in some form. The fifth is the one that decides whether a rejection is a conversation or a process, and it is the one most often left out.

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