ISO 20494:2017

Overview

ISO 20494:2017 - "Paper - Requirements for stability for general graphic applications" specifies measurable stability criteria for papers used in everyday printing and writing applications (e.g., copy paper, brochures, maps, books). It applies to uncoated, coated and filled papers, including those that contain mechanical or recycled fibres. The standard defines test methods, limits and reporting requirements so manufacturers, converters and quality labs can classify papers as suitable for general graphic use.

Key Topics

• Scope and purpose: Stability for normal use and storage (distinct from archival permanence).
• Sampling & conditioning: Follow ISO 186 for sampling; condition specimens at 23 °C and 50% RH per ISO 187.
• Tearing resistance (mechanical strength):
  • Test method: Elmendorf method (ISO 1974).
  • Minimum before ageing:
    • For grammage ≥ 70 g/m²: ≥ 350 mN in any direction.
    • For grammage < 70 g/m²: use formula r = 6g − 70 (with g = grammage in g/m²).
• Retention after accelerated ageing:
  • Accelerated ageing per ISO 5630‑3: 80 °C, 65% RH for 12 days (288 h).
  • Tearing resistance after ageing must be ≥ 80% of pre-age value.
• Chemical stability:
  • Alkali reserve: ≥ 0.8 mol/kg (ISO 10716). If provided by calcium carbonate, equivalent to ≥ 40 g CaCO3/kg.
  • pH of cold aqueous extract: 7.5 to 10.0 (ISO 6588‑1).
• Reporting & compliance: Test report must reference ISO 20494 and include sample ID, conditioning, results, deviations and test environment. A statement of compliance format is provided (Annex E).

Applications

ISO 20494:2017 is used by:

• Paper manufacturers to design and certify printing/writing grades (including those with high-yield or recycled fibres).
• Paper buyers, converters and printers to specify stable paper for office, commercial printing and publications that are not intended for permanent archival storage.
• Quality control and testing laboratories performing tear, pH and alkali reserve tests and accelerated ageing. Practical benefits include predictable mechanical performance after normal use, broader options for sustainable fibre use, and market transparency for coated/uncoated papers.

Related Standards

• ISO 186 - Sampling to determine average quality
• ISO 187 - Standard atmosphere for conditioning and testing
• ISO 536 - Determination of grammage
• ISO 1974 - Elmendorf tearing resistance method
• ISO 5630‑3 - Accelerated ageing (80 °C, 65% RH)
• ISO 6588‑1 - pH of aqueous extracts
• ISO 10716 - Determination of alkali reserve
• For archival permanence: ISO 9706 and ISO 11108 are referenced for papers intended for long‑term storage.

Keywords: ISO 20494:2017, paper stability, general graphic applications, tearing resistance, alkali reserve, accelerated ageing, pH of aqueous extract, coated papers, uncoated papers, recycled fibre.