How to Evaluate Tile Samples, Calibre, Shade and Packaging

Know which sample you are holding

“Sample” covers very different things, and each answers a different question:

• Hand or showroom samples are cut pieces, small tiles or catalogue boards. They show design, colour and finish, and nothing about dimensions or lot consistency.
• Full-size production samples are taken from a real production run. They let you check size, flatness, thickness and the shade of that particular batch.
• Pre-shipment or lot samples are pulled from your own order before loading. These are the ones that matter for acceptance.

Digitally printed designs add a further complication. Most marble, stone and wood looks are printed with several different faces, or graphic variations, so that the floor does not repeat. One or two pieces cannot show the full pattern. Ask for a complete face set, or for a laid-out photograph of enough pieces to show every face, before you judge the design.

Size, calibre and squareness

Tiles shrink as they are fired, and not every tile shrinks by exactly the same amount. Factories therefore sort non-rectified tiles into calibre groups by actual size and print a calibre code on each carton. Tiles from different calibres can differ slightly in size, so mixing them on one floor produces uneven grout joints and lines that drift out of true.

Rectified tiles have their edges ground after firing to a precise size and square edge, allowing narrower grout joints. They are usually supplied as a single calibre, but still check, especially across repeat orders.

How to measure

• Measure all four sides of several tiles with a digital caliper, not a tape measure.
• Measure both diagonals; a difference between them indicates the tile is out of square.
• Compare the results with the declared work size, not just the nominal size on the label.

Permitted deviations for size, squareness and straightness depend on the product group and the standard the supplier declares, such as ISO 13006 or ANSI A137.1. Ask which standard the supplier’s tolerances refer to, and write the accepted values into your approval sheet. Verify the dimensional tolerances that apply to the exact product group and standard before accepting a sample

Shade, tone and lot

Raw materials, glaze batches and kiln conditions all vary slightly, so colour varies between production runs. Factories sort finished tiles into shade (or tone) codes and print the shade, calibre and a batch or lot number on the carton. Tiles from different shades should not be mixed in one installation.

Some designs are meant to vary. Many North American manufacturers describe intended variation on a four-step scale from V1 (uniform) to V4 (substantial or random variation). Verify the V1–V4 shade-variation scale definitions against ANSI A137.1 or the manufacturer’s literature Agree whether the variation you see in the sample is the design or a defect.

How to judge shade

• Lay several pieces side by side on the floor and view them from standing height, not at arm’s length on a desk.
• Look in daylight and under the lighting your customers use; some glazes shift noticeably between the two.
• Photograph the layout with a neutral reference in the frame, so you can compare future lots.

Flatness, thickness and surface quality

Flatness and warpage

Place a straightedge across the centre, the edges and the diagonals of the tile and check any gap with feeler gauges. Large formats are more sensitive: a small bow over 1200 mm or more can cause lippage (uneven edges between neighbouring tiles), cracked joints or hollow spots. Note whether any warpage is convex or concave, because it affects how installers offset and level the tiles.

Thickness

Measure thickness at several points on several tiles. Consistent thickness matters for setting beds and for transitions to other floor finishes.

Surface

Inspect at standing distance under good, even light; standards describe a defined viewing distance and lighting for this check. Verify the surface-quality inspection method, distance and lighting in ISO 10545-2 or the declared standard Look for edge and corner chips, pinholes, glaze crawl or bare spots, print banding or lines from the digital printer, colour spots, and uneven polish on lappato finishes. On polished and high-gloss faces, use a low, raking light to reveal fine scratches.

The back of the tile

Check the back for arrows showing the laying direction, any lot or production marks, and the body colour. A clean, well-defined back pattern also helps adhesive contact.

What to test in a laboratory, not on your desk

Water absorption, breaking strength and modulus of rupture (ISO 10545-4), abrasion, slip resistance, frost resistance and chemical or stain resistance all need controlled laboratory methods. Desk tests such as a drop of water on the back or a key scratched across the glaze are informative at best and misleading at worst.

Ask for full reports from an independent or accredited laboratory that are recent, name the standard and edition, and cover the exact size, finish and body you are buying. Our porcelain, ceramic and GVT guide explains which properties matter for which applications.

Check the packaging sample too

Ask for a packed carton, not just loose tiles. Packaging is where many export claims begin, and it is much cheaper to change before production than after.

• Carton board feels rigid and does not crush easily at the corners when stacked or lifted by its edges.
• Corner or edge protection fits the tile size, with separators between glossy faces where needed.
• Print is legible and the label shows product name or code, size, calibre, shade, lot, pieces per carton, m² per carton and gross weight.
• Country of origin and any destination-market marking are present. Verify origin and labelling requirements for each destination market
• Laying-direction arrows and handling symbols are consistent with the tile itself.

Pallets, strapping and container loading are covered in our export packing guide.

A simple sample evaluation sheet

Record the approval so it holds

An approval that lives only in an email thread is hard to enforce. Make it physical and specific:

• Approved reference sample. Sign, date and label matching pieces, and keep one set with the supplier and one with you.
• Approval sheet. List product code, size, accepted calibre, shade tolerance, finish, thickness, flatness criteria, defect limits, packaging and label requirements, and the test reports relied on.
• Pre-shipment inspection. Before loading, have cartons drawn from the finished lot and compared with the reference sample, using an agreed sampling plan, commonly based on ISO 2859-1 (AQL). Verify which ISO 2859-1 inspection level and AQL values suit your order with your inspection provider

If you are still choosing a supplier, see our questions for an Indian tile supplier, and read more about our approach on quality and packaging.