ISO 5630-6:2009

Overview

ISO 5630-6:2009 - "Paper and board - Accelerated ageing - Part 6: Exposure to atmospheric pollution (nitrogen dioxide)" specifies a laboratory method to accelerate ageing of printing and writing papers by exposing sheets to a controlled concentration of nitrogen dioxide (NO2). The method evaluates changes in mechanical and optical properties to help predict a paper’s stability to long-term natural ageing in polluted air. It applies to all cellulose-based printing and writing papers, including coated and filled grades.

Key topics and technical requirements

• Pollutant and concentration: Polluted air composed of dry air with 0.005% ± 0.0002% by volume NO2.
• Exposure time: Specimens are exposed for 120 h ± 0.5 h.
• Apparatus: Requires a corrosion-resistant ageing chamber, gas delivery and control system, humidity and temperature control per conditioning climate, and an exhaust system (removing ≈ 5% of chamber volume per hour) to avoid build-up of degradation products.
• Specimen mounting: Sheets are hung on removable support bars (holes in four corners), prevented from touching chamber walls or other specimens.
• Conditioning and atmosphere: Pre- and post-ageing conditioning in the dark following ISO 187; testing atmospheres must be controlled.
• Measurements:
  • Mechanical: Fold number (machine direction) per ISO 5626; report fold-number retention R = (F2 / F1) × 100%, where F1 = fold number before ageing and F2 = after ageing.
  • Optical: b* coordinate in CIE 1976 (Lab*) per ISO 5631‑1; report change Δb* = b2 − b1.
• Sampling and reporting: Follow ISO 186 for representative sampling; test report must include conditioning climate, number of tests, fold-number data, b* means and deviations, and any deviations from the method.
• Safety: NO2 is highly toxic - follow supplier SDS and laboratory safety procedures.

Applications and users

• Predicting long-term stability of printing and writing papers exposed to polluted environments (urban archives, libraries, commercial prints).
• Quality control and specification development by paper manufacturers and converters.
• Material selection and conservation planning for archives, museums, libraries, and cultural heritage professionals.
• Research and development in pulp and paper laboratories assessing effects of additives, sizing, fillers and alkaline reserves on pollutant sensitivity.
• Independent testing laboratories offering accelerated ageing services.

Related standards

• ISO 5630 series (other accelerated ageing parts: Part 1, Part 3, Part 4, Part 5)
• Normative references: ISO 186, ISO 187, ISO 5626, ISO 5631‑1

Keywords: ISO 5630-6:2009, accelerated ageing, paper testing, nitrogen dioxide, atmospheric pollution, fold-number retention, b* colour coordinate, paper stability, cellulose-based papers.