Contrôle des effets détériorants de la lumière sur les objets de musée = Control of deteriorating effects of light upon museum objects

Abstract

This journal article documents the effects of light on museum materials. Theories of light energy, photochemical activity, color temperature, black body (Planckian) radiators are discussed. Both ultraviolet and visible radiation are harmful. At equal levels of intensity, zenith skylight is most hazardous, followed by fluorescent lamps and incadescent. Degradation characteristics include fading, yellowing and embrittlement. Extent of deterioration depends upon radiation intensity, exposure time, spectral characteristics of radiation sources and absorption capabilities of radiant energy by certain materials. High temperatures, moisture content of materials, Rh and the presence of oxygen increase the rate of deterioration. Reduce illumination and exposure time. Eliminate ultraviolet (UV) by using blinds, UV absorbing filters, or reflecting light from surfaces containing zinc oxide or titanium white. Yellow filters eliminate photochemically potent wavelengths of visible light. Generally accepted levels of illumination are: 50 lux for light sensitive materials (silk, newsprint, watercolors), 150 lux for moderately sensitive materials and 300 lux for materials of little sensitivity. 1 foot candle = 10.764 lux. The article is illustrated with numerous charts, tables and photographs. References (1888-1964) are included.