What an inspection includes and what laboratory testing covers

This article describes common industry practice, not official rules.

An inspection and a laboratory test answer different questions. An inspection looks at a sample of finished goods at the factory and compares them with the buyer's specification and the approved sample. A laboratory test measures properties of a product under controlled conditions, which cannot be judged by looking at it. The two are often used together, but neither one replaces the other.

What an on-site inspection usually includes

An inspector usually visits the factory when the order is finished or close to finished. The inspector draws a sample from the lot and checks it against the reference documents. These commonly include the purchase order, the specification, the technical drawing or artwork, and the approved sample. The inspector is usually a third party that is not the factory or the seller.

The checks usually cover:

• Quantity and packing, compared with the packing list
• Appearance, including color, surface finish and visible defects
• Workmanship, such as stitching, assembly and how parts fit together
• Measurements, taken with simple tools against the technical drawing
• Function tests on site, using the equipment already at the factory
• Packing and labels, including shipping marks and label content

The inspector records what was seen on that day in the inspection report. Defects are usually sorted as critical, major or minor, as set in the inspection checklist. The report describes the sample and the lot at the time of the visit. It does not describe goods the factory has not yet made.

What laboratory testing covers

Laboratory testing measures properties that cannot be judged by looking at a product or by using simple tools. Those measurements need instruments, controlled conditions and trained staff. The laboratory works on a sample sent to it and issues a test report with the results. The test report usually states the test conditions and the test instructions the laboratory followed, as agreed with the buyer.

A test report describes the sample that went to the laboratory. It does not show how the rest of the lot was packed or labeled. For a given product, whether a legal or certification requirement applies is for the regulator or an accredited laboratory to confirm.

How the two differ

	On-site inspection	Laboratory testing
Where it happens	At the factory, on finished goods	At a laboratory, on a sample sent there
What it looks at	Appearance, workmanship, measurements, function on site, packing and labels	Properties measured under controlled conditions
How results are judged	By the inspector, against the specification and the approved sample	By instruments, against the test instructions
What it produces	An inspection report of what was seen that day	A test report with the results

How buyers commonly combine the two

A common approach is to use the two activities at different points in the order:

• Testing on pre-production samples, before the factory runs the full order, to check materials and design.
• Testing on samples drawn from production while the order is running.
• Inspection of the finished goods and packing before shipment, against the approved sample.

Which mix fits depends on the product and on what the purchase contract says. It is worth agreeing in writing which tests are run, on which samples, and what the inspection checklist covers, before production starts.

Can a test report replace an inspection?

Usually not. A test report covers the sample that went to the laboratory. An inspection covers how the goods were finished, packed and labeled at the factory, and the test report does not record those things.