Overview
ISO 8254-3:2016 - Paper and board: Measurement of specular gloss - Part 3: 20° gloss with a converging beam (TAPPI method) - specifies a standardized method to assess the specular gloss of paper and board at an incidence/reflection angle of 20°. It is intended chiefly for high‑gloss surfaces (cast‑coated, lacquered, highly varnished or waxed papers and high‑gloss ink films). The measurement uses a converging beam geometry (TAPPI method) and references a polished black‑glass standard with refractive index 1.540.
Key topics and technical requirements
- Measurement geometry: Light incident at 20° to the surface normal; reflected light detected within a defined aperture using a photodetector.
- Apparatus: Gloss meter with a converging lens system, light source, photodetector, matte-black light‑tight housing, and means to hold samples flat.
- Gloss standards:
- Primary/high‑gloss reference (black glass, n = 1.540) defines the scale.
- Intermediate and working standards calibrated against the high‑gloss reference.
- Zero‑gloss standard (black velvet cavity) for zeroing.
- Calibration: Zero check (source off/on), warm‑up, adjust to high‑gloss reference value, verify with intermediate standards; re‑check working standard regularly during runs.
- Sampling & conditioning: Test pieces representative of the lot (ISO 186 for sampling); condition samples at 23 °C and 50% RH per ISO 187. Avoid moisture exposure (>65% RH can reduce gloss).
- Procedure: Minimum of five test pieces (ten if both sides measured); record gloss in machine/cross directions and repeat measurements to obtain mean values.
- Documentation & precision: Instrument optical specifications (Annex A) and precision data (Annex B) are included; test report requirements defined.
Applications and users
ISO 8254-3:2016 is used to:
- Control quality in paper and board manufacturing for high‑gloss products.
- Verify finish in printing, coating and converting (varnish, lacquer, film inks).
- Provide acceptance criteria in specifications and lab testing for suppliers and purchasers.
Typical users:
- Quality engineers and laboratory technicians in paper mills and converters
- Packaging and label manufacturers
- Print quality control teams
- Instrument manufacturers and calibration laboratories
Related standards
- ISO 8254-1 and ISO 8254-2 (other gloss angles/methods)
- ISO 2813 and TAPPI T653 (origin of the TAPPI method)
- ISO 186 (sampling) and ISO 187 (conditioning)
- Note: Commercial 20° gloss meters for paints/plastics may use different reference refractive index (e.g., 1.567) and are not directly compatible with ISO 8254-3:2016 readings.
Practical keywords: ISO 8254-3:2016, 20° gloss, specular gloss measurement, TAPPI method, gloss meter calibration, paper and board gloss.
Open preview (PDF)Paper and board — Measurement of specular gloss — Part 3: 20 degree gloss with a converging beam, TAPPI method