Common Woven Fabric Defects and the 4-Point System: How to Grade Polyester and Nylon
A roll can pass every physical test you specified — shrinkage, tear strength, colour fastness all inside tolerance — and still be expensive to cut. Appearance defects do not show up in a test report. They show up as cut-out loss, second-quality garments and arguments at the cutting table. This guide covers how visible defects on woven polyester and nylon are classified, what each family looks like and where it comes from, how the four-point system turns what an inspector sees into one number, and how to write an acceptance clause that still holds when a shipment is disputed.
Appearance Is a Cutting-Room Event, Not a Lab Result
Laboratory testing answers structural and colour-fastness questions. None of the standard tests answers the question the cutting room actually asks: does this roll contain interruptions that fall inside a pattern piece? A fabric can meet every numeric target on our list of items in a fabric test report while carrying reed marks every few metres.
The cost model is blunt: a fault inside a pattern piece usually cannot be repaired, and one small mark writes off the material for the whole garment.
The Four Families of Visible Defects
Defect names vary between mills and regions, which is why classification by origin is more useful than memorising vocabulary. Almost everything visible falls into four families.
| Family | Typical faults | Where it originates | How it reads on the cloth |
|---|---|---|---|
| Yarn-direction | Broken or missing ends and picks, coarse or thin picks, double end, slubs | Weaving: warp preparation, loom stoppages, yarn irregularity | Linear marks running along length or width |
| Open places and holes | Holes, tears, dropped stitches of structure, selvage damage | Loom damage, transport, stenter pins and clips | Absence of material, often at the selvage |
| Stains and foreign matter | Oil, rust, dye spots, water marks, soiling, residue | Lubrication, handling, dyeing auxiliaries, storage | Localised discoloration, often found late |
| Shade and surface | Shading bars, side-to-centre differences, listing, crease and rope marks | Dyeing, drying, heat setting, calendering | Gradual or repeating tonal banding |
Warp-Direction Faults
A broken end leaves a gap in the warp sheet; if the loom continues, the fabric carries a narrow line of loose structure until the end is repaired. Missing ends, double ends and reed marks belong to the same family. Reed marks show as regularly spaced vertical lines where the reed wires have held the warp unevenly, and they are easiest to see on smooth constructions.
A start-up mark, sometimes called a draw-back place, appears where the loom stopped and restarted: the pick spacing changes across a few centimetres, and after dyeing that band picks up differently. On a flat, dense plain weave it is visible across the room; on a deliberately slubbed or textured article it may disappear. That difference is one of the reasons weave construction should be settled first — our comparison of polyester woven weaves explains how much of this is structurally determined.
Filling-Direction Faults
A coarse pick is a weft yarn thicker than its neighbours; a thin place is the opposite, sometimes called an open place when enough picks are missing to leave a visible window of structure. Both read as bands across the width. A mispick or double pick produces a short localised double line, and a snarl — a weft yarn that has twisted back on itself instead of lying flat — leaves a small loop on the face.
Textured polyester and nylon carry residual torque; if the yarn is not set consistently, isolated loops appear after wet processing rather than on the greige roll. Snarls are therefore invisible in greige inspection and only visible once the fabric has been dyed.
Holes, Selvage Damage and Stains
Holes are unambiguous and usually mechanical: a hook during handling, a pin on the stenter frame, a damaged clip line. Stenter damage is the pattern to look for, because it repeats — marks at a fixed distance from the selvage, at a pitch corresponding to the machine's pin spacing. Damaged or cut selvage narrows the usable width even when the rest of the roll is clean, which links directly to the usable-width and yield question covered in the specification framework in our polyester woven buyer's guide.
Stains are found latest and cost the most. Oil and rust can be invisible until the cloth is pressed, and auxiliaries may migrate during storage. Specify inspection lighting, and remember that a fault found at the garment factory costs far more than one found before shipment.
Shade Faults: Bars, Listing and Piece-to-Piece Differences
This family causes most quality disputes. A shading bar is a repeating tonal band across the width, usually with its origin in the dyeing machine rather than the loom. Side-to-centre difference, often called tailing or listing depending on the pattern, means the edges and the middle of the same roll do not match. End-to-end shading means the beginning and end of one roll differ.
The mechanisms behind these are covered in our walkthrough of how polyester woven fabric is dyed. Two practical consequences follow. First, side-to-centre must be judged full width under consistent lighting, not on a folded swatch. Second, cut panels from one roll should be adjacent in the garment; a shade difference within one garment reads as a defect even when each panel sits inside tolerance on its own.
Marks Left by Printing and Finishing
Printed cloth adds its own vocabulary: misregistration, where one colour sits off its intended position; doctor streaks from the squeegee; screen blockages leaving gaps; and pin holes where the paste has not penetrated. These faults are pattern-related, so any standard must state whether faults inside the printed motif are assessed differently from faults in ground areas.
Finishing leaves marks too. Uneven brushing during peach sanding streaks the surface; calendering can create moiré where two periodic structures interfere; softener and resin residues can leave patchiness that only appears after pressing. For identification purposes, our article on hand-feel finishing routes sets out which mechanical step leaves which signature.
The Four-Point System, Line by Line
The four-point system is the most widely used grading method for finished apparel fabric. An inspector examines the roll on a frame under controlled overhead light and assigns penalty points by defect length, regardless of whether the fault runs along the length or the width of the fabric.
- Up to 75 mm (3 in) — 1 point
- Over 75 mm and up to 150 mm (6 in) — 2 points
- Over 150 mm and up to 230 mm (9 in) — 3 points
- Over 230 mm (9 in) — 4 points
- A hole larger than 25 mm is normally treated as a four-point fault wherever it occurs
- No single linear metre or yard may be charged more than 4 points, however many faults it contains
Confirm two conventions before shipment: inspection speed, since faults are missed on fast frames, and whether every roll is inspected full-length or only a stated percentage.
Turning Faults Into One Number
The penalty points themselves are meaningless without normalising them to area. The conventional expression is points per 100 square yards, calculated as follows: multiply the total penalty points by 3,600, then divide by the inspected length in yards multiplied by the cuttable width in inches. Equivalently in metric terms, express penalty points per hundred square metres, using centimetres and metres consistently.
Typical acceptance levels sit around 20 to 28 points per 100 square yards, with the stricter end used for lightweight smooth constructions. These figures are conventions, not standards — the number that matters is the one in your purchase agreement.
Writing an Acceptance Clause That Survives Argument
A clause that grades defects but omits the operating conditions will be argued about. Six lines close most of the gaps.
- Name the grading system — four-point, including the maximum points per linear unit rule.
- State pass and reject thresholds — per-roll maximum plus batch average, not one number alone.
- State sampling and speed — percentage of rolls inspected, and metres per minute on the frame.
- State the lighting and viewing distance, and who keeps the reference standards.
- Define the zero-tolerance list — usually holes, contamination, and any fault inside a named panel size.
- State the remedy — replacement, credit, cutting allowance, and the time window for a claim.
The last line is the one most often forgotten. Without an agreed remedy and a claim deadline, a grading result is an opinion rather than a term of the contract.
When a Roll Fails
Three outcomes usually beat shipping a roll back. A cutting allowance covers extra material. Repacking into shorter pieces removes unusable metres while keeping most of the value. Pairing — cutting a garment's panels from adjacent areas of one roll — resolves small shade differences without rejection. Availability depends on the order and is confirmed on request.
Frequently Asked Questions
Is 20 points per 100 square yards the correct pass level?
It is a widely used convention, not a standard. Typical practice falls between 20 and 28 points per 100 square yards. The number should reflect construction: smooth, lightweight weaves show faults more readily than textured ones.
Can defects be inspected only once, after finishing?
Final inspection is the one that matters for acceptance, but two-stage inspection is cheaper. Some faults, such as weft snarls on filament yarn, only appear after wet processing; others are easier to trace to their origin on greige cloth.
Who should run the inspection?
Either party can, provided the method, lighting, sampling rate and retained reference are agreed in writing beforehand. Most disputes come from a difference in method rather than a difference in the fabric.
Does a lab test report replace visual grading?
No. Physical tests and visual grading answer different questions. Fastness and strength numbers describe behaviour in use; grading describes interruptions in the cloth that will cause cut-out loss.
What should I do about faults found after cutting has started?
Stop and document: piece numbers, positions measured from a defined datum, photographs under agreed lighting, and retained swatches. Claims made with that level of detail are far easier to settle than general statements.
Next Step
Visual grading is only useful if it is written down before production rather than argued about afterwards. Send us the construction, end use and the acceptance level you need to work to and we will come back with the grading method, the lighting and sampling conditions, and the clauses we suggest for that construction. If you already work to a house standard, send that document as the reference and we will quote against it rather than impose a generic one.
