Overview
ISO 12040:1997 - "Graphic technology - Prints and printing inks - Assessment of light fastness using filtered xenon arc light" - specifies an accelerated method to assess the light fastness of prints and printing inks using a filtered xenon arc lamp that simulates daylight. The standard applies to all print substrates (paper, board, thin metals, plastic films) and all printing processes. It defines required apparatus, exposure conditions, evaluation scales and reporting items for consistent, reproducible testing.
Key topics and requirements
- Test principle: expose the test print and blue wool references together to filtered xenon arc light and compare deterioration.
- Light source: xenon arc lamp with colour temperature 5 500 K to 6 500 K; air- or water-cooled as per manufacturer.
- Filtering: glass filter that absorbs radiation below 310 nm and is ≥90% transparent from 380–700 nm (simulates sunlight behind window glass).
- Reference scale: eight blue wool references (ratings 1–8) representing increasing light fastness; comparison uses the blue wool reference that changes similarly to the test piece.
- Colour change assessment: use the ISO grey scale (ISO 105-A02) - a “distinct change” is equal to or less than grade 3. Dual ratings (e.g., 6-7) allowed between adjacent references (not below rating 5); append “N” if the sample darkens.
- Temperature control: measure sample temperature with a Black-Panel Thermometer (metal plate ≥45 × 100 mm); samples must not exceed 45 °C.
- Exposure procedure: includes recommended successive covering technique to assess prints with different fastness levels in a single run.
- Inks: inks are tested on standardized prints prepared per ISO 2834 and evaluated as prints.
- Test report: must reference ISO 12040, give light-fastness rating, test conditions (temperature/humidity), instrument model, any light-dark cycling, and whether substrate fastness was tested.
Applications and users
Practical uses:
- Quality control and R&D for ink manufacturers, commercial printers, and packaging printers.
- Color durability testing for publishers, labels, and outdoor/indoor printed material where simulated sunlight exposure is needed.
- Conservation, testing laboratories, and specification writers who require standardized accelerated lightfastness data.
Who benefits:
- QA managers, laboratory technicians, product developers, print buyers, and standards/specification authors.
Related standards
- ISO 105-B02 (Textiles - fading lamp test; xenon arc)
- ISO 105-A02 (Grey scale for assessing change in colour)
- ISO 2834 (Preparation of standardized prints)
- ISO 3664 (Viewing conditions for colour assessment)
Keywords: ISO 12040:1997, light fastness, filtered xenon arc, blue wool references, graphic technology, prints, printing inks, accelerated lightfastness test.
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