ISO 18935:2018

Overview

ISO 18935:2018 - Imaging materials - Colour images - Determination of water resistance of printed colour images specifies standardized test procedures to assess the relative water resistance of printed colour images. Applicable to both digital and analogue prints, the standard defines qualitative categories of water resistance and four practical test methods that simulate everyday and catastrophic water exposure (spills, wiping, soaking, edge immersion). It is intended for reproducible, within-laboratory evaluation rather than absolute interlaboratory quantification.

Key topics and requirements

• Scope: Applies to colour prints produced by a variety of imaging processes (inkjet, photographic, etc.).
• Categories of water resistance:
  • Water resistant - not noticeably affected by liquid water.
  • Moderately water resistant - some reversible or minor damage; still usable.
  • Not water resistant - easily damaged by incidental water contact.
• Test specimens & controls: Untreated control specimens are required for visual comparison. All specimens should be dried at ambient conditions for at least 24 hours before testing.
• Test media: Use deionized or distilled water for all tests (pH not controlled unless certified).
• Primary test methods (qualitative assessment):
  • Method 1 - Standing water evaporation: Small water drops placed on colour patches and left to evaporate.
  • Method 2 - Standing water plus wiping: Water placed on prints then removed with a weighted tissue swipe to simulate wiping before drying.
  • Method 3 - Water soak: Immersion for 1 hour followed by vertical drying to model flood-like exposure.
  • Method 4 - Edge immersion: Lower edge immersion (typically 24 hours) to test water penetration from an exposed edge; samples tested with paper grain both parallel and perpendicular to water surface.
• Colour targets: Tests include cyan, magenta, yellow, red, green, blue and black patches (black as produced by user-specified driver settings).
• Evaluation approach: Qualitative visual assessment (bleeding, smearing, gloss changes, delamination, curl) rather than fixed numeric pass/fail thresholds.

Practical applications

• Quality control for print manufacturers, ink and substrate developers, and print service providers evaluating water durability of printed colour images.
• Photo labs, digital print shops and conservation labs using the standard to assess vulnerability of prints to spills, handling, flooding or disaster recovery.
• Archival preservation and disaster-planning teams that need to categorize materials for salvage prioritization after water damage.
• R&D and comparative testing when developing water-resistant coatings, laminates or new inks.

Who uses this standard

• Print manufacturers and materials suppliers (inks, coatings, substrates)
• Imaging laboratories and print service providers
• Conservation professionals and archives
• Product test labs and quality assurance teams in photography and imaging industries

Related standards

• Prepared by ISO/TC 42 (Photography); ISO 18935:2018 sits alongside other ISO photographic/imaging standards covering image permanence, testing methods, and materials characterization. For implementation, consult your national standards body or ISO for the complete technical context.

Keywords: ISO 18935:2018, water resistance testing, printed colour images, imaging materials, inkjet durability, standing water, water soak, edge immersion, photo conservation.