A sealed, coded sample is a portion of your lot closed with a numbered, tamper-evident seal and labelled with a code rather than the supplier's name. The seal shows nobody changed it after sampling. The code links it to the lot without telling the lab who made it.
Together they turn a lab result into evidence. Without them, a report shows only that some product passed.
What the seal and the code do
A seal can be a numbered plastic security seal, a tamper-evident bag with a printed serial number, or tape signed across the closure. When the lab receives the sample, it records the seal number and notes whether the seal was intact. If the seal number on the report matches your sampling record, you know the sample was not swapped or topped up on the way.
The code is a short reference written on the sample in place of names. It does four jobs.
- Links: the code ties the sample to a lot number and bag list in your sampling record.
- Blinds: the lab does not know which supplier, or which buyer, the sample belongs to.
- Compares: you can send samples from several suppliers under codes and compare them fairly.
- Checks: you can send a known sample under a code now and then to test the lab itself.
The sampling record
The seal and code only work with a written record made at the time. It should state the lot number, number of bags, which bags were sampled, the code, the seal numbers of each part, the date and the names of those present. The seller signs it too. A photo of the sealed samples next to the lot marking helps.
Keep the record with the contract. If a claim arises months later, it is the document that links the lab report to the shipment.
Counter-samples
The aggregate sample is usually split into at least three parts, each sealed. One goes to the lab. One stays with the seller. One is kept by you or your agent as a counter-sample. If the result is disputed, the counter-sample can be tested at a second lab, and both sides know it is the same material.
Store counter-samples cool, dry and dark, and for at least the shelf life you claim or the period in your contract. See pre-shipment versus approval samples for how this fits with other samples.
Common mistakes
- Sealing a sample the supplier has already prepared, rather than drawing it yourself.
- Using unnumbered seals, or not writing the number down.
- Labelling the sample with the supplier's name.
- Letting the supplier courier the sealed sample.
- Not keeping a counter-sample.
How we help
We draw, seal and code samples at the factory, record the bag and seal numbers, and courier the lab portion ourselves. We hold a sealed counter-sample for you. Ask for a free sourcing review.