ISO 18930:2011

Overview

ISO 18930:2011 - "Imaging materials - Pictorial colour reflection prints - Methods for evaluating image stability under outdoor conditions" - defines standardized test equipment, procedures and reporting for assessing the colour stability of pictorial photographic and digitally printed images exposed outdoors. It establishes how to measure image change during outdoor aging (both real-time outdoor weathering and accelerated laboratory simulations) but does not set pass/fail criteria or acceptability limits. Users select test end-points that simulate their intended display application.

Key topics and technical requirements

• Scope of media covered: Prints on coated papers, films, vinyl, polyester, synthetic papers, plastics, laminated or not; dye- and pigment-based inkjet (aqueous, solvent, phase-change, UV-curing); thermal dye transfer, dye sublimation, dye-diffusion-transfer, xerographic and liquid-toner prints, chromogenic and silver dye-bleach, and color direct thermal prints.
• Test types:
  • Accelerated laboratory weathering - simulated exposure combining light, water (spray) and elevated temperature to accelerate degradation. Xenon arc lamps with daylight filters are recommended to simulate the spectral distribution of sunlight.
  • Outdoor weathering - real-time exposure in defined locations; accelerated outdoor weathering (e.g., focused sunlight) is recognized separately.
• Measurement and reporting: Colour changes are monitored instrumentally (optical density and/or CIE Lab* values, ΔE). Critical image-change parameters to report are identified; users document printing system settings so tests are repeatable.
• Limitations and cautions: The standard excludes physical-stability tests (support embrittlement, cracking, delamination). Results from one printer/ink/mode/media combination are not transferable to different combinations.
• Test control and uncertainty: Addresses conditioning, specimen preparation, number of replicates, apparatus, interferences, safety, and reporting protocols to ensure reproducibility.

Practical applications and who uses it

ISO 18930 is used by:

• Print manufacturers and material suppliers validating print longevity, color stability and weather resistance of outdoor signage, posters, window graphics (external), vehicle wraps and outdoor displays.
• Test laboratories performing accelerated weathering and outdoor exposure studies.
• Brand owners, graphic designers and specifiers seeking objective measurements for material selection and durability specifications.

Benefits include consistent, repeatable methods for comparing materials and processes, improving product development, and supporting claims about outdoor color stability.

Related standards

• ISO 18937 (indoor window graphics - sunlight filtered by glass)
• ISO 18941 (ozone testing considerations)
• ISO 4892-1 / ASTM G151 (accelerated weathering device guidance)
• ISO 13655, ISO 11664-4, ISO 5-3, CIE 85 (colorimetric and spectral measurement references)

Keywords: ISO 18930, image stability, outdoor weathering, accelerated weathering, pictorial colour reflection prints, xenon arc, daylight filter, print longevity, color stability testing.