Overview
EN ISO 10545-16:2012 (identical to ISO 10545-16:2010) specifies a laboratory method for quantifying small colour differences between plain-coloured ceramic tiles intended to be uniform. The standard defines the measurement principle, required equipment, sampling and calculation procedures using CIE Lab* and the CMC colour-difference formulation (∆Ecmc). It allows suppliers, manufacturers and specifiers to agree a maximum acceptable colour tolerance (commercial factor, cf) based only on closeness of match, not on the nature of the colour shift.
Key topics and requirements
- Scope: Applies to plain coloured tiles where small colour differences are important; not for artistic or intentional variegation.
- Measurement systems: Use a reflectance spectrophotometer or tristimulus colorimeter conforming to CIE instrument geometries (45/0, 0/45, d/0, 0/d). For diffuse geometries the specular component must be included.
- Observer and illuminant: Use daylight illuminant D65 with a 10° observer for CIELAB calculations.
- Sampling: Reference batch: at least five tiles representing the homogeneous batch; test specimens: statistically determined but never fewer than five tiles.
- Preparation: Clean surfaces with laboratory-grade isopropanol and dry with a lint-free, non-fluorescent cloth or tissue.
- Measurement procedure: Take three alternate readings per tile (reference and test), average them and use those averages for colour-difference calculations.
- Calculations: Compute CIELAB (L*, a*, b*, C*, H*) and component differences, then calculate ∆Ecmc using ISO 105-J03 equations. The CMC l:c ratio can be adjusted (typical l:c ≈ 1.5:1 for smooth, high-gloss glazed tiles).
- Acceptance criteria: Compare ∆Ecmc to an agreed commercial factor (cf); specimens with ∆Ecmc ≤ cf pass, others fail.
- Reporting: Test report shall reference ISO 10545-16 and include tile description, instrument and measurement conditions, ∆L*, ∆C*, ∆H*, agreed cf, average ∆Ecmc and l:c ratio.
Applications and users
- Quality control in tile production (glazed and unglazed)
- Incoming inspection for specifiers, distributors and retailers
- Laboratory testing services and third-party conformity assessment
- Architects, designers and project managers who require tight colour matching
- Procurement and contractual specifications where objective colour tolerance is needed
Practical benefits include objective, repeatable assessment of colour match, prevention of visible mismatches on installation, and a clear basis for acceptance/rejection of tile lots.
Related standards
- ISO 105-J03:2009 - Calculation of colour differences
- CIE 015:2004 - Colorimetry (spectral reflectance → XYZ)
- ISO 11664-4/CIE S 014 - CIE 1976 Lab* space
- ISO 13006 - Ceramic tiles: definitions and classification (related commercial factors)
- ISO 23603/CIE S 012 - Spectral quality of daylight simulators
Keywords: EN ISO 10545-16:2012, ISO 10545-16:2010, ceramic tiles, colour differences, CMC ∆E, CIELAB, spectrophotometer, colorimeter, colour measurement, tile quality control.
