ISO 18937-1:2023

Overview

ISO 18937-1:2023 - "Imaging materials - Methods for measuring indoor light stability of photographic prints - Part 1: General guidance and requirements" is the foundational part of a multi‑part ISO series that establishes general guidance for laboratory measurement of the indoor light stability (lightfastness) of photographic prints and films. It applies to reflection prints (colour and monochrome), transparent/translucent films and backlit display prints, and sets out requirements for selecting methods, conditioning specimens, operating exposure devices, and reporting results. This part does not prescribe specific lamp types (those are in subsequent parts) nor test procedures for physical degradation of supports or binders.

Key topics and technical requirements

• Scope and principle: Defines the purpose of accelerated indoor light stability testing and limitations when extrapolating to real‑world display life.
• Laboratory exposure device requirements: Performance and control requirements for devices that expose specimens to laboratory light sources - including measurement and control of irradiance/illuminance, spectral characteristics, temperature (black‑panel and chamber), humidity, device uniformity, and air quality.
• Test specimens and preparation: Guidance on specimen selection, mounting, conditioning and handling to ensure reproducible results.
• Test conditions and procedure: Requirements for setting and maintaining test set‑points, allowable deviations, exposure duration and consideration of intermittent vs. continuous exposure.
• Reporting requirements: Mandatory data to include in test reports so results are interpretable and comparable (irradiance, spectral data, temperature/humidity, specimen details, device calibration).
• Important phenomena addressed: Explanation of reciprocity failure (non‑linear behaviour when switching between high‑intensity/short‑time and low‑intensity/long‑time exposures) and other limitations of accelerated testing.

Practical applications and users

ISO 18937-1 is used to:

• Support R&D and quality control for photo paper, inks, colorants, films and print media.
• Provide performance requirements and calibration/verification procedures for manufacturers of artificial accelerated lightfastness devices.
• Guide independent testing laboratories and certification bodies in standardized indoor lightfastness measurement.
• Inform conservators, museums and archivists assessing display strategies and expected image stability.
• Help print service providers and OEMs compare material stability across workflows.

Who benefits: material manufacturers, device producers, testing labs, conservation professionals, print manufacturers and product development teams.

Related standards

• ISO 18937-2 (xenon‑arc lamp exposures) and ISO 18937-3 (LED lamp exposures) - specific lamp/test procedures.
• ISO 18930 - outdoor light stability.
• ISO 18913 - imaging permanence vocabulary.
• ISO/TR 18945 - background on light fading considerations.

Keywords: ISO 18937-1, indoor light stability, photographic prints, accelerated lightfastness, irradiance, reciprocity failure, exposure device requirements, test reporting.