Four-Point

In commercial fabric procurement and mill quality control, four-point refers to one of two distinct standards:

1. The 4-Point Fabric Inspection System (ASTM D5430): The global visual grading system used on cloth inspection frames to evaluate weaving defects, holes, stains, and assign First Quality vs Second Quality grades.
2. Burst strength: A laboratory test that measures the force needed to rupture a fabric specimen under local pressure. It is a different family of standards altogether, and the numbers most often attached to it are wrong — see the section below.

1. ASTM D5430 4-Point Fabric Inspection System

The 4-point system is the standard visual grading method used on mill inspection tables before packing and shipping. During inspection, cloth passes over an illuminated surface at controlled speeds (typically 20–30 meters per minute). Inspectors assign penalty points from 1 to 4 based on defect length:

Maximum points per linear yard

No single linear yard can be penalized more than 4 points, regardless of how many defects are clustered within that yard. However, consecutive defects occurring across multiple yards indicate systematic loom issues (such as a chipped reed, blocked waterjet nozzle, or dragging harness) and trigger an automatic roll reject.

Point calculation formula

Because rolls vary in length and cuttable width, penalty points are normalized to points per 100 square yards:

$\text{Points per } 100 \text{ sq. yd} = \frac{\text{Total Penalty Points} \times 3,600}{\text{Inspected Yards} \times \text{Cuttable Width (inches)}}$

(Alternative metric formula: $\text{Points per } 100 \text{ m}^2 = \frac{\text{Total Points} \times 10,000}{\text{Inspected Meters} \times \text{Width in cm}}$)

The width in the formula is the cuttable width, not the loom width. A 280 cm loom width that yields 260 cm of cuttable cloth is a different denominator from a 240 cm loom yielding 230 cm, and the same roll of defects gives a different score on each. That is the first thing to check when two mills' inspection reports disagree.

First Quality acceptance thresholds

The acceptable point threshold is agreed upon in the purchase contract based on fabric type and end use:

• Apparel and fine lining polyester (taffeta, pongee): $\le 20 \text{ to } 24 \text{ points per } 100 \text{ sq. yd}$.
• Home textiles, drapery, and wide bedding wovens: $\le 24 \text{ to } 28 \text{ points per } 100 \text{ sq. yd}$.
• Automatic second quality flags: Any roll exhibiting continuous shade variation (side-to-center or end-to-end), noticeable odor, or repeating warp/weft streaks is marked Second Quality regardless of the numerical point count.

2. Burst strength — and the standard numbers that get mixed up

Burst strength is a different subject from the inspection system, and the standard numbers around it are routinely confused. Two corrections matter here, and both are the kind of mistake that costs a buyer a laboratory report they cannot use.

First: ISO 1419 is not a burst test. It is Rubber- or plastics-coated fabrics — Accelerated-ageing tests, the Tropical Test, which ages a coated fabric under heat and humidity to see whether the coating lets go. It is a real and useful test for coated cloth, and it has nothing to do with bursting a woven fabric. A report citing ISO 1419 is an ageing report, not a burst report.

Second: these are the bursting standards.

And the four-point method is not one of them. The four-point burst — a circular specimen clamped in a fixture and pressed against a rigid plate by an extending ring — was the traditional method for woven fabrics. It has no current number in the ISO 13938 series, which has two parts, and no ASTM number either. It survives on older laboratory equipment and on older specification sheets, and it is still what people mean when they say "four-point burst".

So a buyer who receives a burst figure has three questions, and the first one is not about the fabric: which method produced it, under which standard, and compared with what. The hydraulic, pneumatic and diaphragm methods do not give comparable numbers, and a four-point figure is not comparable with any of them. A supplier who quotes a bursting strength without naming the method has quoted a number you cannot compare against anyone else's.

What burst strength measures

Burst strength tests the fabric, not the yarn. Because the load is applied as pressure over an area rather than as a pull along an axis, the result reflects the cloth's behaviour as a plane — how it distributes stress, whether yarns can mobilise together, and how the weave structure responds locally. That is why the same fabric can have a burst figure that does not track with its tensile strength: burst rewards a structure that shares load across yarns, tensile rewards one that resists a direct pull.

A woven construction will normally burst at a much higher force than a knit of the same weight, because a knit can open and distort under local pressure while a woven structure holds until yarns break. Burst is therefore a strong discriminator between constructions.

Where it is used

Burst strength is specified less often than Martindale or tensile, but it matters in specific places:

• Medical and hygiene fabrics — drapes, gowns, scrubs, where a local puncture is a clinical failure
• Protective and barrier fabrics — where a localized breach is unacceptable
• Geotextile and industrial cloth — bags, filters, filtration components
• Coated and laminated cloth — to check the substrate survives finishing
• Bag and sack fabric — where local stress is concentrated

For ordinary apparel and upholstery, burst is rarely the governing test. It is worth asking for when the end use involves localised loading rather than distributed wear — that is the situation burst models.

Reading the number

General considerations rather than a specification table, because the useful figure depends entirely on the construction — and, before the construction, on the method:

The last two are why burst figures vary between suppliers more than tensile figures do: a test on unconditioned cloth straight off the loom will not match a laboratory report taken a week later.

What to ask a supplier

1. Which method and standard? ISO 13938-1 hydraulic, ISO 13938-2 pneumatic, ASTM D3786 diaphragm, or a legacy four-point fixture — and if it is a four-point figure, ask what it was compared against.
2. Conditioned or as-received? Ask for the conditioning time and atmosphere.
3. Greige or finished? A finish changes the result, and the finish is what you buy.
4. Tested in warp or weft, or an average? Woven fabrics can differ by direction.
5. Was the specimen taken from the edge or the body of the roll? Edge specimens can pick up selvage effects.

Why this is a mill conversation

Burst strength is one of those figures that is very sensitive to how the cloth was made — yarn tension, loom condition, and the finishing route. A trading intermediary quoting a burst number has taken it from a supplier's datasheet for a fabric that may not be the fabric in your order. Asking the mill directly, against your own construction, is the only way the number means anything.

The same is true of the inspection score, for a different reason: the 4-point figure depends on the defect the loom actually made and on the width the number was calculated over, and both are visible only at the mill.

Mill greige context

Burst is measured on the finished cloth. On Weaverine greige polyester programs the woven base sits roughly in the 55–120 GSM range at 160–330 cm widths in plain and twill constructions, and because woven structures hold until the yarns break while knits open locally, the result tracks that construction far more than the fibre. A plain weave at the top of the weight range and an open leno at the bottom are not comparable fabrics, and their burst figures should not be compared either.

Worth asking whether the mill tested the base or the finished article, and in which state it was conditioned. A figure taken off the loom will not match a laboratory report taken a week later. For the base specification, use the product page.

Weaverine does not publish a burst figure or a 4-point inspection score on this page. Both results belong to a specific construction, a specific width and a specific condition state, and a generic number would describe cloth nobody is buying. Request the test report against your specification, and check that it names the method, the standard and the conditioning.