Overview
ISO 10545-16:2010 - Ceramic tiles - Part 16: Determination of small colour differences - specifies a laboratory method to quantify small colour differences between plain-coloured ceramic tiles intended to be uniform. The standard uses instrumental colour measurement (spectrophotometers or trichromatic colorimeters) and the CMC colour-difference formula to produce an objective ∆Ecmc value. This allows manufacturers, testing laboratories and specifiers to set a maximum acceptable tolerance for colour conformity that depends only on closeness of match, not on the visual nature of the difference.
Key topics and technical requirements
- Measurement method: Use a reflectance spectrophotometer or trichrome colorimeter; geometries permitted are 45/0, 0/45, d/0 or 0/d. For diffuse geometries the specular component must be included.
- Reference conditions: Use illuminant D65 and 10° observer for CIELAB calculations (L*, a*, b*, C*, h).
- Colour-difference metric: Calculate CMC colour difference ∆Ecmc (l:c) per ISO 105-J03:2009 (calculations and component conversions), and decide an l:c ratio (e.g., 1.5:1 often used for high-gloss glazed tiles).
- Commercial factor (cf): A tolerance value agreed between parties; ∆Ecmc is compared to cf to accept or reject batches. (Note: ISO indicates anticipated commercial factors in ISO 13006 when revised.)
- Sampling and measurement protocol:
- Reference sample: at least five tiles from the same pigment mix (to avoid metamerism).
- Test sample: representative random selection - never fewer than five tiles.
- Clean tile surfaces with laboratory-grade isopropanol, dry with a non‑fluorescent absorbent cloth.
- Take three measurements per tile, alternate reference and test tiles, and average the three readings for calculations.
- Reporting: Include instrument details, ∆L*, ∆C*, ∆H*, agreed cf, mean ∆Ecmc and l:c ratio.
Applications and who uses it
- Quality control in ceramic tile manufacturing (production conformity, batch acceptance).
- Independent testing laboratories performing tile conformity tests for suppliers and clients.
- Architects, specifiers and purchasers who need objective criteria for colour matching between tile batches.
- Construction and tiling contractors verifying delivered tiles before installation.
Practical value: objective, repeatable colour control, reduced disputes, and traceable acceptance criteria.
Related standards
- ISO 105-J03:2009 (calculation of colour differences)
- CIE 015:2004 (Colorimetry)
- ISO 11664-4/CIE S 014 (CIELAB space)
- ISO 13006 (ceramic tile definitions/classification - commercial factors reference)
- ISO 23603/CIE S 012 (spectral quality of daylight simulators)
Keywords: ISO 10545-16:2010, ceramic tiles, colour differences, ∆Ecmc, CMC, spectrophotometer, colorimeter, CIELAB, D65, quality control.
