To check tile grade at the factory, start with the factory's written grade definition, then open randomly chosen packed boxes and look at the tiles laid out under good light. Compare what you see with an approved reference sample and with the written definition, not with your memory of a showroom board.
Grade is a sorting decision made by people and machines at the end of the line. Checking it means checking that decision on your own lot.
Before you go: fix the definition
Factories call their grades Premium, Standard and Commercial, or use names such as Export or AAA, but each plant defines them differently. Our guide to Premium, Standard and Commercial grades explains the names.
Before production, get the definition in writing for your grade. It should say which defects are allowed, how many per box, at what viewing distance, and what happens to tiles that fail. Attach it to your purchase order.
Use the standard as a floor. ISO 13006 requires at least 95% of first-quality tiles to be free of visible defects when inspected as set out in ISO 10545-2. A factory's Premium grade should be at least that good.
Set up the inspection properly
- Choose boxes at random from the packed stock of your order, across different pallets and production days.
- Lay the tiles out flat on a clean floor or table, in rows, under even light.
- View them from standing height and at the distance named in your definition, then close up for anything you notice.
- Keep an approved reference sample, signed by both sides, next to the layout for comparison.
- Record the design, shade, calibre and batch on each box you open.
How many boxes to open
The number of boxes to open comes from your sampling plan. Our article on AQL for tile inspection explains how to set it.
What to look for
Grade defects are mostly surface faults. Look for chips on edges and corners, pinholes, glaze drops, spots, print lines, colour patches, cracks and polishing marks on polished tiles. Check that the printed design is sharp and that the faces of the design repeat as expected.
Then check the things that affect laying. Put tiles edge to edge and check that joints are even. Check flatness with a straight edge across the diagonal. A tile can be free of surface faults and still be a poor grade if it is warped or out of size.
Why grade drifts
Grade problems are rarely about one bad tile. They come from sorting that loosens over a long run, from borderline tiles pushed into a higher grade, or from lower-grade stock added to make up quantity. Our article on how grade sorting is done on the line explains where these slips happen.
If more boxes fail than your plan allows, do not accept a promise to fix it later. Ask the factory to re-sort the lot, then inspect it again before loading.
How we help
We agree the written grade definition with the factory, inspect your packed lot against it and stop loading if it fails. To set this up for your next order, book a free sourcing review.