CIE 157:2004 — Control of damage to museum objects by optical radiation
About this book
CIE Publication 157:2004, Control of Damage to Museum Objects by Optical Radiation, is the primary international technical reference for professionals responsible for the lighting of museum collections, archival materials, and heritage objects. Produced by the International Commission on Illumination (CIE), Technical Committee 4-15, this document synthesises photochemical research on light-induced degradation and translates it into practical recommendations for exhibition and storage environments. The publication opens with an analysis of the photodegradation mechanisms by which optical radiation damages sensitive materials.
It distinguishes between photochemical reactions driven by ultraviolet (UV) radiation (wavelengths below 400 nm), which are particularly aggressive toward organic dyes, paper, and biological specimens, and the lower but non-negligible damage contributed by the visible spectrum, especially the blue-violet component (400–500 nm). Infrared radiation is treated primarily as a thermal risk — causing dimensional changes and cracking in panel paintings and wooden artefacts — rather than a photochemical agent. CIE 157 introduces the concept of damage dose, measured in megalux-hours (Mlx·h) or, when UV content is significant, in microwatts per lumen (μW/lm) as a measure of relative UV content of a light source.
The document presents the widely cited sensitivity classification of museum materials into three groups: most sensitive (textiles, watercolours, documents, natural history specimens), sensitive (oil and tempera paintings, undyed leather, horn), and least sensitive (stone, glass, ceramics, metals). For the most sensitive category, a maximum annual exposure of 150,000 lux-hours is recommended, equating to a 50 lux display illuminance for approximately 3,000 hours per year. The document provides comparative data on the UV emission characteristics of different light source types available at the time of publication — tungsten halogen lamps, metal halide discharge lamps, fluorescent tubes, and early LED modules — together with guidance on UV filtration using acrylic glazing or sleeve filters on fluorescent tubes.
It also addresses the reflective UV component from surfaces within display cases. Practical chapters cover case studies in illuminance measurement, the design of display cases with controlled microenvironments (temperature, RH, O₂ levels) to reduce oxidative degradation in the absence of light, and protocols for monitoring cumulative exposure using UV dosimeters and dataloggers. The role of illuminance meters with cosine-corrected detectors and UV radiometers in routine measurement programmes is explained.
CIE 157:2004 remains a foundational text for museum lighting design, conservation science, and building services specification in heritage buildings, even as LED technology has subsequently transformed the practical landscape by offering near-zero UV emission and adjustable spectral power distributions. Its methodological framework — damage dose, sensitivity classification, lux-hour budgets — is still referenced in subsequent guidance from the Illuminating Engineering Society (IES) and the International Council of Museums (ICOM).