How should I keep a PVA yarn counter-sample for a dispute?

Agree the sample before a dispute starts

A retained sample is useful only when both parties can connect it to the delivered material and understand how it was obtained. Add the retention plan to the purchase documents before an order ships: how many portions are taken, from which packages, who keeps each portion, how they are sealed, and what question each portion may be used to examine.

Do not call a convenient yarn end a counter-sample if no one recorded its source. A sealed hank taken from one package represents that package; it does not automatically represent every cone or carton in a mixed delivery. Where a later dispute could affect several lots, preserve the lot boundaries and package identities during sampling.

Keep identity and custody with the yarn

If the sample is divided between buyer and supplier, make the portions as comparable as the test permits and label them before they leave the same controlled selection. Keep a witness or image of the split when the issue has high commercial impact. A later photograph of a loose strand cannot repair missing chain-of-custody information.

Protect the condition without inventing a shelf life

Use the packaging and storage instructions that apply to the exact product, and record the conditions under which each portion is held. Do not assume a retained sample remains unchanged indefinitely. If an exposure concern is part of the dispute, document the sample's actual handling history rather than describing an ideal storage condition that did not occur.

Keep enough material for the agreed method, any repeat specimens, and a reserve for a joint review. The amount depends on the property and laboratory procedure; the supplier or lab should confirm the need before sampling. A counter-sample that is too small can leave both parties arguing about how to divide it after the complaint arrives.

Open the sample under a joint protocol

Before testing, compare the package label, seal log, sample description, and purchase specification. Photograph the seal and contents, note any damage or apparent change, and record whether the test uses the whole retained portion or a prepared specimen. If the sample does not match the written identity, stop and resolve that mismatch before treating its result as evidence about the shipment.

A retained counter-sample complements the site's sample-to-production testing guide, which covers how to plan the original trial. This protocol is for preserving evidence from a shipment after approval.

Write the result back to the order record

After review, keep the test request, method version, custody log, report, and disposition together. State which shipment quantity the result covers and whether the sample has been exhausted. Agree what happens to remaining portions and who authorizes disposal so old material is not later mistaken for an approved reference sample.

Ask procurement and quality to assign one document owner for the retention record. That person should update the sample status when it is opened, sent to a lab, split, or replaced by a new approved reference.