ISO 18935:2025

Overview

ISO 18935:2025 - Imaging materials - Colour images - Determination of water resistance of printed colour images defines standardized, qualitative test procedures to assess the relative water resistance of printed colour images. Applicable to both digital and analogue prints, this fourth edition (minor revision to the 2018 version) specifies test preparation, four complementary test methods, evaluation categories and reporting guidance for prints exposed to water.

Key topics and technical requirements

• Scope and classification
  • Prints are classified into three qualitative categories: water resistant, moderately water resistant, and not water resistant, based on observable changes (colorant bleed, gloss change, curl, delamination).
• Controlled conditions
  • Tests use deionized or distilled water and require ambient conditioning of samples (specified ambient conditions are defined in the document).
  • Untreated control samples are required for comparison.
• Test methods (Methods 1–4)
  • Method 1 - Standing water evaporation: small water drops (applied to multi-colour test blocks) are allowed to stand and dry to simulate spills left to evaporate.
  • Method 2 - Standing water plus wiping effects: evaluates physical integrity of the image layer by applying a drop, waiting 1 minute, then wiping with laboratory tissue under controlled pressure and speed to simulate touching while wet.
  • Method 3 - Water soak: immersion of individual samples in water for 1 hour, then vertical drying, to mimic catastrophic exposure (flood scenarios).
  • Method 4 - Edge immersion: immersing the lower edge of a print for 24 hours (with grain direction considerations) to test capillary penetration from an exposed edge.
• Test pattern and colour requirements
  • Tests use patches of multiple colours (cyan, magenta, yellow, black, red, green, blue); prints must be dried at ambient conditions for at least 24 hours prior to testing.
• Reporting and annexes
  • The standard prescribes what to include in test reports and contains informative annexes (e.g., water emergency scenarios with inkjet prints and resistance to other liquids).

Applications and who should use it

• Print manufacturers and ink/medias developers - for R&D and product comparison of water resistance.
• Quality control laboratories - to assess batch performance and acceptance criteria within a facility.
• Conservators, archivists, museums and libraries - to evaluate salvageability and formulate disaster recovery procedures for colour prints.
• Commercial print service providers and professional photographers - to choose substrates and coatings suitable for end-use environments.
• Disaster response planners - to understand potential damage modes and mitigation for water exposure.

Related standards (if applicable)

• ISO 18935:2025 is part of the ISO imaging materials series (prepared by ISO/TC 42). Users may consult adjacent ISO photographic and imaging-material standards for broader durability, colorimetric and conservation protocols.

Keywords: ISO 18935:2025, water resistance testing, imaging materials, colour images, inkjet prints, standing water evaporation, water soak, edge immersion, print conservation, quality control.