Before submitting samples, confirm the applicable requirement, parts to test, sample origin, test method and decision rule with the buyer's quality team, supplier and laboratory. When the report arrives, compare each result with the limit explicitly applicable to the order and check the sample identity, method version and scope of the conclusion. Mark missing information as pending. Aqueous-extract pH is a measurement of the water extract of the textile tested; it does not comprehensively assess every chemical substance, skin reaction or the safety of an entire shipment.
This guide is for knit garments where aqueous-extract pH needs discussion during purchasing or sample approval and both parties need traceable results. It does not prescribe a universal acceptable range or replace the specific requirements of destination regulations, customer specifications or certification schemes. Determine which requirement applies, when its version takes effect and who is responsible for confirming it. Without a clear basis, do not mark the result as passing or make a safety claim.
Separate the test method from the acceptance limit
The official ISO 3071:2020 abstract describes a method for determining the pH of the aqueous extract of textiles, applicable to textiles in different forms such as fibres, yarns and fabrics. The method describes measurement; whether an order accepts a result requires a separate applicable acceptance requirement. A method number is not proof of passing, and another style's limits must not replace those for this style.
Ask the laboratory whether it can test the proposed material using the buyer's specified method and version, and whether the test falls within its relevant scope of accreditation if the buyer requires accreditation. The buyer and laboratory should confirm whether different methods or versions are interchangeable; similar names alone do not establish equivalence. Sample preparation, specimen quantity, extraction and instrument operation are for the laboratory to perform under the applicable method and its procedures; this guide does not offer a substitute recipe for the standard.
Decide what to submit and what it represents
Identify style, order, colour, size, yarn or fabric lot, sample revision, finishing condition and origin on the submission form. Identify the parts to assess, such as the main knit fabric, a neck edge touching the skin or decoration made from another material. Which components need separate testing, whether they may be combined and how many samples are needed per colour or lot should be decided with the buyer and laboratory in light of the requirements and actual construction. Do not assume a combined result proves each component.
A development sample, pre-production sample and production-lot sample are different objects. Record who sampled, date, location, quantity, seals and handover so the report can be traced to the submitted items. If the supplier sends them, confirm their representative scope too. Ask the laboratory about required quantity, packaging and transport conditions; keep a retained reference sample and, where possible, record its relationship to the reported sample. A pass for one colour does not automatically cover another colour, another material lot or a different finishing process.
| Question before submission | Record or confirm | If unresolved |
|---|---|---|
| Which requirement applies? | Name, version and limit of the customer or destination requirement | Do not yet conclude it passes |
| What is tested? | Sample identity, part, colour, lot and preparation condition | Confirm the sampling plan with the laboratory |
| How is it measured and judged? | Method version, laboratory capability, limit and decision rule | Obtain written confirmation first |
| What does the result cover? | Corresponding order, parts, colours and lots | Mark uncovered items pending |
This is a purchasing discussion checklist, not a fixed sampling plan prescribed by a standard. Selected samples may not represent every production variation. The parties should explicitly balance cost, time and the scope requiring coverage, and retain a record of what was not tested.
Check the report and borderline results
Check the laboratory name, report number, sample description and receipt information, method and version, result, unit or reporting format, any deviation, conclusion and applicable limit. Verify that each planned part or combination was tested and that the specific sample associated with the result matches the order. If pages are missing, parts unclear or the applicable requirement version unknown, ask the laboratory to clarify and resubmit if necessary. Other tests listed in the report cannot substitute for the aqueous-extract pH result, nor can pH substitute for other tests.
For a result near a limit, first confirm whether the agreed decision rule accounts for measurement uncertainty and how the report expresses it, then ask the laboratory to explain. Do not independently round the result, alter limits or repeatedly select favourable results. The US National Institute of Standards and Technology's definition of a decision rule describes how measurement uncertainty is considered when stating conformity. The definition itself does not determine whether a particular report passes; agree the applicable rule at commissioning and follow the relevant requirement.
For illustration only, suppose a customer specifies a pH range of 5.0 to 7.0 for the sample and the result is 6.0. Under an agreed simple numerical comparison it lies within the range, but the sample and other agreed conditions still need checking. If the result is 7.0, proximity to the boundary alone does not establish the uncertainty rule or final decision. These numbers are entirely hypothetical, not law, a universal industry limit or a WTBF promise.
Address a failure or change
If a result does not meet the applicable requirement, retain the original report and notify the people responsible for quality decisions on both sides. Check sample identity, method, limit and possible deviations; do not immediately treat the result as a conclusion about the whole lot, and do not ignore it. Ask the supplier and laboratory to investigate possible causes and agree whether new samples are needed, which affected parts or lots require retesting and the basis for it. Without confirmation, do not assert that a particular auxiliary, process step or washing method caused the result.
After changing finishing, dyeing, materials or supply source, retain the versions and processing records before and after the change and confirm with the buyer which affected items need resubmission. A passing retest supports only its corresponding sample and agreed scope; other unconfirmed colours, parts or lots remain pending. For receiving discussions beyond testing, see the bulk knitwear receiving and quality claims guide.
Information for the supplier and laboratory
Use the WTBF inquiry page to provide a style drawing, materials and contact areas, colours and sizes, quantities per style and colour, destination, applicable customer specification and version, required method, sample or lot information, target timing and any existing report. Ask the supplier what samples and records it can provide, and confirm cost, required sample quantity, timing and report contents with the laboratory. WTBF knit pullovers offer style references; testing and purchasing arrangements depend on the information agreed by both parties.