JAIC 1996, Volume 35, Number 1, Article 2 (pp. 09 to 21)
INVESTIGATION OF A SURFACE TARNISH FOUND ON 19TH-CENTURY DAGUERREOTYPES
LEE ANN DAFFNER, DAN KUSHEL, & JOHN M. MESSINGER
ABSTRACT—A specific tarnishing pattern was first observed in 1992 in a large collection of daguerreotypes viewed under short-wave ultraviolet illumination. While daguerreotypes have been closely inspected under visible light, there appears to be no report of the use of short-wave ultraviolet illumination, a straightforward examination and documentation technique available to conservators. The scope of this investigation includes preliminary analysis, characterization of the tarnish, and a study of its rate of occurrence on a group of 110 daguerreotype plates. Two methods of instrumental surface analysis were used in this study: scanning electron microscopy and Fourier transform infrared analysis. These useful, nondestructive analytical methods are available to the conservator for examination and documentation and provide both inorganic and organic data. The findings indicate that the presence of this fluorescing tarnish may provide evidence of specific past treatments applied to daguerreotype plates. The fluorescing tarnish can serve as a monitoring guide for measuring the deterioration in daguerreotype plates.