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Proceedings Paper

A versatile microfadometer for lightfastness testing and pigment identification
Author(s): Andrew Lerwill; Joyce H. Townsend; Haida Liang; Stephen Hackney; Jacob Thomas
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Paper Abstract

The design and experimental method for the use of a novel instrument for lightfastness measurements on artwork is presented. The new microfadometer design offers increased durability and portability over the previous, published design, broadening the scope of locations at which data can be acquired. This reduces the need for art handling or transportation in order to gain evidence-based risk assessments for the display of light-sensitive artworks. The instrument focuses a stabilized high powered xenon lamp to a spot 0.25 millimeters (FWHM) while simultaneously monitoring color change. This makes it possible to identify pigments and determine the lightfastness of materials effectively and non-destructively. With 2.59mW or 0.82 lumens (1.7 x107 lux for a 0.25mm focused spot) the instrument is capable of fading Blue Wool 1 to a measured 11 ΔEab value (using CIE standard illuminant D65) in 15 minutes. The temperature increase created by focused radiation was measured to be 3 to 4°C above room temperature. The system was stable within 0.12 ΔEab over 1 hour and 0.31 ΔEab over 7 hours. A safety evaluation of the technique is discussed which concludes that some caution should be employed when fading smooth, uniform areas of artworks. The instrument can also incorporate a linear variable filter. This enables the researcher to identify the active wavebands that cause certain degradation reactions and determine the degree of wavelength dependence of fading. Some preliminary results of fading experiments on Prussian blue samples from the paint box of J. M. W Turner (1755-1851) are presented.

Paper Details

Date Published: 16 July 2007
PDF: 12 pages
Proc. SPIE 6618, O3A: Optics for Arts, Architecture, and Archaeology, 66181G (16 July 2007); doi: 10.1117/12.726029
Show Author Affiliations
Andrew Lerwill, Tate (United Kingdom)
Nottingham Trent Univ. (United Kingdom)
Joyce H. Townsend, Tate (United Kingdom)
Haida Liang, Nottingham Trent Univ. (United Kingdom)
Stephen Hackney, Tate (United Kingdom)
Jacob Thomas, Tate (United Kingdom)

Published in SPIE Proceedings Vol. 6618:
O3A: Optics for Arts, Architecture, and Archaeology
Costas Fotakis; Luca Pezzati; Renzo Salimbeni, Editor(s)

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