Coating type in Oxford fabric: Range, Tolerance and How to Test It

Coating type is the figure that gets written into a purchase order and then measured by nobody. This is what it controls, how to measure it, and what happens when it drifts.

What coating type actually controls in Oxford

PU is soft and breathable-ish; PVC is cheaper and stiffer; PE is for disposable goods.

This is why two suppliers can quote the same headline price and deliver products that behave differently in the second year.

For Oxford fabric, the working range is PU / PVC / PE / none. Inside that band the choice is commercial; outside it, the product changes category and so does the price.

How to choose a coating type option

These are alternatives, not points on a scale. Coating type is chosen by the application rather than by price, and a supplier who quotes one option as if it were interchangeable with another is quoting a different product.

Specifying the ceiling is only justified when the end product carries a warranty that would be expensive to honour. Otherwise it is cost without a customer-visible benefit.

The figure that decides the outcome is not coating type itself but the tolerance around it. A supplier who quotes PU / PVC / PE / none without a tolerance has not quoted a specification, and the first lot will define the tolerance for you.

How to measure coating type

The reference method here is Tear strength, run to ASTM D2261 tongue tear, with an acceptance of >= 25 N for 600D bag goods. The method is the easy part; sampling and conditioning are where reports diverge.

Ask which instrument was used. For coating type, two instruments that both claim the same standard can differ by enough to move a marginal lot from pass to fail.

Record the measured value rather than pass or fail. A marginal pass on coating type tells you the process is running at the edge, which is the information you need before the next lot rather than after it.

Coating type does not stand alone

Coating type moves with coating weight (15-60 gsm per pass) and with hydrostatic head (800-5000 mm). Tightening one usually costs money in another, and a supplier who accepts every tolerance without comment has either not understood the interaction or is planning to substitute.

If a quotation is significantly cheaper, the difference is usually in one of these neighbours rather than in the figure being discussed.

The clause to write for coating type

The line below is the version we can quote against without inventing anything. Coating type appears with a tolerance and a test, not as a standalone number.

600D polyester oxford, 2-pass PU coating with primer, 1500 mm hydrostatic head, 155 cm usable, 62 gsm total coating, tear >= 25 N, Pantone 19-4052 TCX, hydrolysis-resistant

Write it once and reuse it. The buyers who avoid claims are not stricter than everyone else; they send the same well-written clause every time.

When coating type goes wrong

Hydrolysis in storage. New rolls smell acidic and the coating turns tacky after a few months in a hot warehouse.

The cause is usually moisture plus heat attacks the pu; common with cheap polyester-based pu in tropical ports.

The test that catches it: 70 C / 95 % RH for 7 days, then re-test adhesion and hand.

What to specify instead: Ask for hydrolysis-resistant PU, desiccant in the container, and a 12-month shelf-life statement.

The pattern is consistent: the failure appears months after delivery, is hard to attribute, and the cost lands on the buyer. That is the argument for measuring coating type on every lot rather than on the development sample.

Four questions about coating type, before you order

1. What tolerance do you hold on coating type, and what did your last three lots measure against it?
2. Which method do you use for tear strength, and which laboratory signs the report?
3. When coating type falls outside PU / PVC / PE / none, do you rework, downgrade, or ship and hope?
4. Which of coating weight or hydrostatic head would you move first to hit a lower price?

The answers are more useful than a certificate, because they show whether the process is controlled or merely inspected. Full ranges for Oxford are on the product page, and the measurement regime is described on the quality control page.

Failure modes worth a clause in the purchase order

Claims rarely come from a batch that was obviously wrong. They come from a coating weight figure that sat inside the quoted band and outside what the product needed.

The other two, with acceptance numbers attached, are in the full failure analysis for Oxford. A supplier who cannot name the mode he sees most often is describing a catalogue, not a process.

Seven lines that turn a quotation into a specification

Most post-delivery arguments are not about quality. They are about a document that never said which figure would be measured, on which instrument, at whose cost.

1. Hydrostatic head: the figure you will accept inside the 800-5000 mm band, the tolerance on it, and the method used to measure it.
2. Base weight (90-260 gsm before coating): name the number, not the word. If the answer only repeats the band, ask which point inside it is being offered for this order.
3. Tear strength: >= 25 N warp / >= 25 N weft (600D) is the market band. Fix the figure you will test at goods-in, and the instrument you will test it with.
4. Usable width (150-160 cm): fix the value per shipment, and state who pays for the re-test if a lot lands outside it.
5. Price validity: the period during which the quoted figure holds, and what happens to it when the raw-material index moves.
6. Remedy: rework, replacement or credit, and the point at which each applies.
7. Sample retention: one production sample per lot stays with the mill for twelve months. Claims are settled against it, not against memory.

Related reading

• Base weight in Oxford fabric
• What Oxford Really Costs
• Oxford fabric