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. The Four-Point Burst Test (ISO 1419): A mechanical burst-strength test that presses a clamped circular fabric specimen against a rigid plate until it ruptures.

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

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. Four-Point Burst Test (ISO 1419)

Four-point burst (or 4-point burst) is a burst strength mechanical test. A circular fabric specimen is clamped over a rubber diaphragm and pressed against a rigid plate by an extending ring until the fabric bursts. The force needed is recorded in Newtons (or kgf).

There are two main burst methods and they are not interchangeable:

For a woven mill, ISO 1419 four-point is the relevant one. Mullen is the knit and nonwoven method. If a supplier quotes a burst figure without naming the method, it is not interpretable.

What it actually measures

Four-point burst 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

Four-point burst 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, four-point 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:

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. ISO 1419 or ASTM D3786? For woven fabric it should be ISO 1419.
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.

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 four-point burst figure on this page. The result belongs to a specific construction 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 ISO 1419 and states the conditioning.