Overview
ISO/TR 10688:2015 - "Paper, board and pulps - Basic terms and equations for optical properties" is a Technical Report that collects and standardizes the formulae, definitions and constants used to compute optical properties of pulp, paper and board. It is intended to be used alongside the specific ISO measurement standards and is particularly valuable for the development of software and instrumentation that compute optical metrics in accordance with ISO/TC 6 standards.
Key topics
- Standardized terms and definitions for optical metrics such as brightness (ISO and D65 variants), whiteness, tint, gloss, opacity and transmittance.
- Colourimetry basics: CIE colour matching functions, chromaticity coordinates and CIE/CIE Lab* (CIELAB) colour space definitions for different observer/illuminant combinations (e.g., C/2°, D65/10°).
- Reflectance and Y-value calculations, including luminous reflectance factor and related conversions.
- Kubelka–Munk theory: conditions for use and equations to compute light-scattering (s) and light-absorption (k) coefficients from reflectance data, including methods specific to 950 nm and grammage-based expressions.
- Colour metrics and indices: dominant wavelength, CIELAB colour coordinates and colour differences (ΔEab), CIE-whiteness and tint, fluorescence component (F), metamerism index and yellowness index.
- Measurement context and instrumentation: references to instrument geometry, calibration requirements, UV-level adjustments (e.g., R457 at 457 nm, half bandwidth 44 nm) and relevant ISO instrument standards.
Practical applications
- Software developers and instrument manufacturers: implement consistent, ISO-compliant algorithms for computing brightness, whiteness, reflectance, scattering/absorption coefficients and colour coordinates.
- Quality control and laboratory analysts in the pulp & paper industry: interpret and compare optical test results reliably across labs and instruments.
- R&D and color scientists: model optical behaviour (opacity, transmittance, fluorescence) and evaluate effects of fluorescent whitening agents (FWAs) under different illuminants (C, D65).
- Purchasing/specification teams: specify measurement procedures and acceptance criteria based on standard optical metrics.
Who should use it
- Instrument vendors building spectrophotometers or reflectometers for paper measurement.
- Independent test labs calibrating instruments or writing analysis software.
- Process engineers and QA managers in paper and board production implementing ISO-based optical specifications.
- Researchers working on paper coatings, fillers and optical brighteners.
Related standards
ISO/TR 10688:2015 is a concise reference that ensures consistent use of formulae, constants and terms across software, instruments and laboratories measuring optical properties of paper, board and pulps.