Why Do Buyer and Supplier Thickness Readings Differ for PU-Coated Fabric?

Before treating a thickness difference as a material defect, check whether both parties measured the same construction under comparable conditions. The material category, test method, applied pressure, reading time and sampling approach all need to be identified. A photograph of a gauge display cannot establish that two measurements are equivalent.

This guide concerns flexible, textile-backed PU-coated materials used in footwear. It is a practical investigation framework, not a replacement for a laboratory test method. Materials sold under the broad label “PU leather” can have different constructions, so the laboratory should confirm which method fits the actual sample.

Choose the method by material not by the word leather

Several thickness methods may appear on a supplier’s paperwork. Their scopes are worth checking before comparing the numbers.

Sources: ISO 2286-3, SATRA TM27, ISO 2589.

These references are not interchangeable labels. Select a suitable method with the testing laboratory and the buyer, then record it consistently. If an agreed customer specification requires a particular method or modification, disclose that explicitly rather than silently substituting another procedure.

Define the object being measured

Confirm whether the reading concerns the finished coated fabric, a backing before coating, or a later assembly with added foam or lining. These are different measurement objects. FILK describes technical textiles as frequently forming multilayer composites and identifies the textile substrate as an important contributor to the composite’s properties. A total thickness reading does not separately identify each layer. FILK: Textiles and yarns

Record the material code, finish, colour, lot and roll reference alongside the specimen’s location. Check that the supplier’s reference swatch and the buyer’s incoming sample represent the same agreed construction and processing stage. A label or photograph of each sample helps prevent a sample-identity problem from becoming a measurement dispute.

If the construction is unclear, start with our guide to PU surfaces, backings and material structure. Here, “backing” means the supporting layer of the material, not a shoe sole.

Agree one shared measurement record

SATRA’s public TM27 summary describes a defined pressure, a defined interval before reading, measurements at multiple positions and a calculated mean. SATRA’s synthetic-material gauge guidance also stresses controlled pressure and describes placing the specimen between an anvil and a presser foot. These are useful reasons to request more than the displayed thickness value. SATRA TM27; SATRA STD 484 guidance

Use the following record to expose differences between the two setups. It is a proposed buyer–supplier comparison sheet, not a statement that every cited standard mandates every field.

For coated fabrics, ISO 2231:1989 addresses conditioning and test atmospheres. The practical request is therefore to identify the conditioning procedure used, rather than assume that samples measured immediately after arrival and samples prepared in a laboratory are directly comparable. This does not establish how large any difference will be for a particular material. ISO 2231

Keep thickness units distinct from pressure units. Millimetres describe thickness; kilopascals describe pressure. A load value alone does not fully describe contact pressure without the applicable contact area. Do not invent a universal pressure, waiting time or thickness tolerance for all PU-coated footwear materials: obtain the required settings from the agreed method and specification.

Investigate in stages before making the acceptance decision

The workflow below is an editorial synthesis for organising a discrepancy investigation. It does not identify a cause from the reading alone or replace the chosen standard’s instructions.

Stage A Reconcile the records

Place both records side by side. First check sample identity and layer assembly, then method and edition, then setup and preparation. Finally, compare the reporting basis: a local reading and a multi-position mean answer different questions.

If a required detail is missing, obtain it before interpreting the gap. Keep the original results visible. Averaging numbers from incompatible procedures does not make the procedures comparable.

Stage B Plan a controlled cross check

Ask the laboratory to design a comparison using a common, traceable specimen where suitable. Agree the measurement locations, handling and sequence, and confirm whether repeat measurement of the same area is appropriate for that construction and method. If separate specimens are needed, document that change and where each came from.

Use one agreed method and record the settings rather than asking both parties simply to “measure again.” Where two instruments are being compared, check their setup and calibration information first. Let the laboratory specify any necessary recovery or reconditioning between measurements; this guide supplies no generic recovery time.

Stage C Decide what the cross check actually establishes

• If the readings become comparable after the procedure is aligned, the original disagreement alone is insufficient evidence of a production change. Keep the aligned record as the basis for the next comparison.
• If results still differ on the common specimen, investigate the instrument, operator, handling and conditioning factors with the laboratory. Do not assign fault from one comparison.
• If different positions or specimens give different results under one controlled procedure, document that variation and assess it through the agreed sampling plan. A small cross-check does not establish the condition of an entire roll or shipment.

These outcomes point to the next check. None is an automatic pass, rejection or diagnosis.

Keep measurement agreement separate from purchase acceptance

A suitable test method makes a result interpretable. The purchase specification determines what result is acceptable. Before placing or approving an order, agree the target, tolerance, sampling basis and decision rule, including how borderline results and any laboratory-reported measurement uncertainty will be handled.

For the wider order record, use the footwear material sourcing checklist. If you are preparing a reference-sample request, the material-matching page explains how measured sample thickness, a target and a tolerance should be distinguished.

The useful outcome is a traceable comparison: the same defined material, a suitable agreed procedure, recorded conditions and an explicit acceptance basis. That is a firmer starting point for resolving a thickness disagreement than choosing whichever gauge reading is closer to the order target.

Source and method note

This article uses the publishers’ public method descriptions and technical guidance. It does not reproduce or claim to implement the complete paid standards. A laboratory must use the applicable full method and confirm its suitability for the actual construction. No Youxiang product has been tested or assigned a performance claim in this article.

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