In this guideShow
Without a measurable specification there is nothing to inspect
An order that says “same as sample, good quality” is weak. An inspector needs a drawing, material, dimensions and tolerances, a colour standard, a functional test, labelling, packaging, accessories and sampling rules. Every point should lead to one of three results: pass, fail or cannot be verified.
The reference sample — often called a golden sample — must be approved and identified. A photo cannot capture surface finish, smell, stiffness, sound or exact colour. Keep one copy yourself and leave one with the manufacturer; for an expensive project, seal or mark it.
The four inspection points and what each one catches
| Inspection | When | What it reveals | What it is too late for |
|---|---|---|---|
| Sample approval | Before the order | Design, appearance, function | Stability of the mass-production process |
| Pre-production | Before the run starts | Materials, components, documents | Defects that do not exist yet |
| During production | At the first 10–30% of output | Process set-up and repeating defects | The full quantity of finished goods |
| Pre-shipment | When most goods are finished and packed | Quantity, appearance, function, packaging | A cheap fix for the whole batch |
For higher-risk products you can add container-loading supervision. It checks quantity, carton condition, the seal and how the container is loaded, but it does not replace a product inspection.
What AQL means — and what it does not
ISO 2859-1 describes sampling procedures for inspection by attributes. In practice, a set number of units is drawn from a large batch and defects are classified as critical, major or minor. Agreed limits decide whether the inspected lot is accepted or rejected.
AQL is not a percentage of “allowed defective products” in the whole container, and it does not guarantee that an uninspected unit is good. It is a statistical decision rule for a sample. For a safety-relevant feature, the acceptable number of critical defects can be zero, and laboratory testing or a 100% test may be needed.
Define critical, major and minor defects in writing before the inspection. A scratch on the back and a failed protection against injury must never land in the same category.
Pre-shipment inspection checklist
- Ordered and finished quantity, packing status and a random selection of cartons.
- Model, colour, dimensions, weight and material against the specification.
- A functional test that reflects real use, not just switching it on.
- Visual defects judged from an agreed distance and under agreed light.
- Logo, labels, manual, serial number, barcode and language versions.
- Accessories and the contents of every package.
- Carton dimensions, product protection and a drop test if agreed.
- Photos of sampling, measurements, defects and warehouse stock.
- A list of deviations with unit counts and a recommendation, with nothing left out.
The inspector must work from the latest approved document version. A change sent only to one salesperson on WeChat easily never reaches the production line.
How to read the report and decide on the shipment
“Pass” does not mean everything is perfect. Read the defects found, the photos, the sample size, the tests not performed and any access limits. The decision depends on how serious the problem is and how the product is used.
- With a critical defect, do not release the shipment until the cause is fixed and re-checked.
- With a repeating major defect, require sorting or rework and a follow-up inspection.
- With a minor cosmetic defect, decide according to your agreement, your customer and the cost.
- Do not pay the balance on a promise that the fix will happen after shipment.
If the supplier disputes a clear measurement, go back to the order and the reference sample. If the requirement is not written there, the problem is also in your purchasing process.
Quality control does not replace compliance
An inspection can measure the product against your brief, but it does not make the product legal in your market. As the importer you must establish which regulations and standards apply, whether laboratory tests, technical documentation, a declaration of conformity, markings and user information are required.
For electrical goods, children’s products, protective equipment or medical devices, bring in a specialist before the sample stage. Discovering late that a product cannot legally be sold costs far more than changing the design at the start. Before choosing a factory at all, run the eight supplier checks.
Worked example: the same defect at three stages
A company orders a plastic housing where the connector opening is critical. If the dimension is checked on the drawing and the first prototype, a change mainly costs engineering time. If the defect appears in the first 20% of production, the line must stop, units must be separated and the tool or process adjusted. If it is only found after shipment, you add freight, sorting and customer claims.
A good inspection plan assigns each feature to the earliest sensible point: materials and components before production, dimensions and assembly at the first units, quantity and packaging before shipment. A function that depends on long-term use needs a durability test, not a short inspector visit.
When a defect is found, do not only ask how many units are bad. Ask why it happened, since when the process has run this way, how affected units will be separated and what will stop it recurring. A photo of one repaired unit is not proof that the whole batch was fixed. Rework needs its own method and a re-check, because repeated handling can create new scratches or damage threads and seals.
What else to settle before you decide
Archive each inspection report with the order, the approved sample and the specification version. On the next run, compare whether the same defect returns. A repeating deviation shows that the corrective action did not work or never reached the work instructions.
Choose an inspection company by experience with your product category, the tests it can run and its independence. The cheapest inspector without the right gauge cannot verify a critical feature. Before the visit, confirm that the factory will have the finished quantity, warehouse access, power and the samples needed. If you are visiting suppliers in person — for example around the Canton Fair — see how Canton Fair buyer support works.
Sources and how this guide was checked
Sources accessed on 23 October 2026. Inspection practice depends on your product; confirm standards and legal requirements for your target market.
- ISO 2859-1 — sampling procedures for inspection by attributes.
- European Commission: importers and distributors — the importer’s obligations for CE-marked products.
- EUR-Lex: General Product Safety Regulation — general safety duties for consumer products in the EU.
- Alibaba.com Trade Assurance guide — why written order terms matter for platform protection.
