Overview
EN ISO 12625-7:2021 - "Tissue paper and tissue products - Part 7: Determination of optical properties - Measurement of brightness and colour with D65/10° (outdoor daylight)" is a CEN-endorsed ISO test method for instrumental measurement of brightness and colour of tissue under outdoor daylight conditions (D65/10°). The standard defines how to prepare single-ply and multi-ply test pieces, set up instruments, and record results so that optical properties of tissue products are measured reproducibly and traceably.
Key topics and requirements
- Scope: Procedures for instrumental determination of brightness and colour of tissue paper/products under D65/10° (outdoor daylight). Notes distinguish these from C/2° (indoor daylight) measurements in ISO 12625-15.
- Terms and definitions: Includes key optical terms such as diffuse radiance factor and intrinsic diffuse radiance factor that underpin measurement interpretation.
- Apparatus and calibration: Requires instruments designed and calibrated in line with referenced standards (for example ISO 2469, ISO 11475) to ensure accurate D65/10° measurement and traceability.
- Sampling and conditioning: Refers to ISO 186 and ISO 187 for representative sampling and standard atmosphere conditioning before testing.
- Preparation of test pieces: Specific instructions for single-ply and multi-ply products, with precautions where texture or structure affects optical readings.
- Procedure and calculation: Stepwise measurement of D65 brightness and colour (including CIE-based colourimetric reporting) and calculation of single, mean and dispersion values. Annex on precision gives expected measurement repeatability/reproducibility.
- Reporting: Minimum information to include in a test report so results are auditable and comparable.
Practical applications and users
This standard is essential for:
- Tissue manufacturers monitoring product appearance and consistency (brightness, colour).
- Quality control and laboratory staff performing routine optical testing and acceptance testing.
- Product development teams comparing formulations, bleaching or whitening strategies.
- Suppliers and purchasers specifying optical properties in contracts and procurement.
- Test laboratories and certification bodies seeking standardized D65/10° measurement methods for accreditation and reporting.
Benefits include consistent color and brightness data, improved product matching across batches, and defensible specifications for marketing and compliance.
Related standards
- ISO 2469 - Measurement of diffuse radiance factor (diffuse reflectance)
- ISO 11475 - Determination of CIE whiteness, D65/10°
- ISO 12625-15 - Brightness and colour with C/2° (indoor daylight)
- ISO 12625-16 - (other optical methods for tissue)
- ISO 186, ISO 187, ISO 4094, ISO/CIE 11664-4 - sampling, conditioning, calibration and colourimetry references
Keywords: EN ISO 12625-7:2021, tissue paper, optical properties, D65/10°, brightness measurement, colour measurement, tissue products, ISO standard.
