ISO/TS 18950:2021

Overview

ISO/TS 18950:2021 - Imaging materials - Photographic prints - Effect of light sources on degradation under museum conditions - specifies a test method to characterize and compare light-induced degradation of photographic reflection prints displayed in museums. The technical specification applies to analogue and digital colour prints (inkjet, electrophotography, thermal dye transfer, silver‑halide colour paper) but excludes black‑and‑white silver‑halide paper. It addresses typical indoor museum light sources (indoor daylight, LED, incandescent) and the use of optical filters to simulate real display conditions.

Key topics and requirements

• Scope and use profile: Designed for prints displayed framed or unframed, continuously or intermittently, under controlled museum environmental conditions.
• Spectral characterization: Uses relative spectral irradiance (RSI) across 300–800 nm to describe light sources - important for non‑Planckian sources such as LEDs.
• Exposure units and limits: Introduces exposure metrics like Mlx‑h (mega lux hour) and concepts such as limiting exposure and safe display duration for accumulative light exposure.
• Controlled stress factors: Specifies acceptable museum ranges for non‑light stresses - temperature (typical day/night 18 °C–24 °C), relative humidity (30 %–55 %), low ozone (