ISO 11476:2016

Overview

ISO 11476:2016 - "Paper and board - Determination of CIE whiteness, C/2° (indoor illumination conditions)" specifies a standardized procedure to measure the CIE whiteness and CIE tint of papers and boards as perceived under indoor lighting. The method uses full visible spectral radiance-factor data (VIS) rather than the narrow blue-region measurement of ISO brightness, and it includes procedures to quantify the fluorescent component of whiteness and to adjust the instrument UV-content to correspond to CIE illuminant C (representative of indoor illumination).

Key topics and technical requirements

• Measurement principle: Calculation of CIE whiteness and tint from tristimulus values (C/2°) derived from radiance-factor spectra over the full visible range; fluorescence component obtained by comparing measurements with and without UV-driven fluorescence.
• Instrumentation: Requires a calibrated reflectometer or spectrophotometer meeting ISO 2469/ISO 2470‑1 characteristics; ability to adjust UV-content to match CIE illuminant C; option for filter‑type or abridged spectrophotometers with appropriate weighting functions (Annex A).
• UV adjustment and filters:
  • A UV‑adjustment filter (cut‑off ≈ 395 nm) or other device to set relative UV-content.
  • A sharp UV‑cut‑off filter for fluorescence elimination with transmittance ≤ 5% at ≤ 410 nm and ≤ 50% at 420 nm.
• Reference standards: Use non‑fluorescent and fluorescent reference standards (level 3) for calibration and UV adjustment (Annex B). ISO brightness of the fluorescent standard is used to set UV content.
• Performance limits: Photometric linearity up to at least 200% in the fluorescent emission region; black cavity and working standards as specified.
• Scope limits: Not applicable to coloured papers containing fluorescent dyes; specific to fluorescence in the blue region of the visible spectrum.
• Updates: Third edition allows calculations using ASTM E308 for instruments that have bandpass correction while retaining non‑bandpass procedures.

Practical applications and users

ISO 11476:2016 is used for:

• Quality control and production acceptance in paper and board manufacturing (whiteness specifications, batch matching).
• Independent testing laboratories and calibration facilities assessing the visual appearance of coated and uncoated white papers.
• Converters, printers and brand owners specifying whiteness and tint for print performance and perceived color consistency under indoor conditions.
• Instrument manufacturers implementing reflectometers/spectrophotometers and UV‑adjustment features. Benefits include reliable, comparable CIE whiteness values that reflect indoor visual appearance, and the ability to quantify the effect of fluorescent whitening agents (FWAs).

Related standards

• ISO 2469 - Measurement of diffuse radiance factor (diffuse reflectance factor)
• ISO 2470‑1 - Measurement of diffuse blue reflectance factor (ISO brightness)
• ISO 4094 - Calibration of testing apparatus
• ISO 11475 - CIE whiteness under CIE illuminant D65 (daylight conditions)

Keywords: ISO 11476:2016, CIE whiteness, C/2°, paper and board, fluorescent whitening agents, UV adjustment, spectrophotometer, ISO brightness, indoor illumination, CIE illuminant C.