ISO 3135:2025

Overview

ISO 3135:2025 - Marking pens - Durability of written line - Documentary use (DOC) defines minimum quality requirements and test methods to ensure marking-pen writing is durable and suitable for documentary use. The standard specifies how to evaluate resistance of the written line to physical, chemical and environmental stresses so that documents remain legible, tamper-evident and reproducible over time.

Key topics and technical requirements

• Scope: Establishes minimum durability criteria for marking pens intended for documentary use (DOC).
• Durability tests: Written lines are evaluated for:
  • Water resistance (immersion for 24 h)
  • Ethanol resistance (50% aqueous ethanol, 10 min)
  • Hydrochloric acid resistance (10% HCl, 24 h)
  • Ammonium hydroxide resistance (10% NH4OH, 24 h)
  • Bleaching resistance (3% chloramine T, 5 min)
  • Erasure resistance (use of a specified eraser; line must remain until paper shows damage)
  • Light resistance (xenon/fade test using ISO 105-B02 and ISO 105-A02 reference scale)
  • Reproducibility (legibility of photocopies/facsimiles)
• Test materials & apparatus: Includes prescribed performance testing paper (per ISO 12757‑1 / ISO 14145‑1 / ISO 27668‑1), eraser hardness (45 ± 5 Shore A per ISO 868), light test equipment (Fade‑o‑meter / xenotest) and test solutions (specified concentrations).
• Sampling & conditions: Samples tested within six months of manufacture under a standard test atmosphere (specified temperature and relative humidity).
• Marking: Pens compliant with ISO 3135:2025 must be marked with manufacturer/trademark, a DOC indicator, and date-of-manufacture or batch number.
• Test reporting: The standard requires documented test procedures and results to support conformity.

Applications and users

Who benefits from using ISO 3135:2025:

• Marking-pen manufacturers - to design and certify pens for archival and documentary markets.
• Quality and compliance teams - to set acceptance criteria and supplier specifications.
• Testing laboratories - to perform standardized durability and reproducibility testing.
• Archivists, records managers and legal authorities - to select pens that preserve legibility and resist tampering for evidence, records and long‑term storage.
• Procurement specialists - to specify documentary-use (DOC) pens in contracts and purchases.

Practical uses include signing legal documents, archival labeling, evidence documentation and any application where long-term legibility, tamper resistance and reliable reproduction are required.

Related standards

• ISO 105-A02 (grey scale for colour change)
• ISO 105-B02 (colour fastness to artificial light / xenon arc)
• ISO 868 (Shore hardness)
• ISO 12757-1, ISO 14145-1, ISO 27668-1 (testing paper and pen families)

Keywords: ISO 3135:2025, marking pens, durability of written line, documentary use, DOC, water resistance, light resistance, erasure resistance, reproducibility, archival ink standards.