The application of XANES for the examination of silver, gold, mercury, and sulfur on the daguerreotype surface

Abstract

X-ray absorption near edge structure (XANES) spectroscopy was used to study a freshly prepared reference daguerreotype surface as the first step in devising improved methods for the conservation of these important historic artifacts. The results are consistent with the formation of alloy image particles. Interdiffusion of gold and silver has led to the development of a silver–gold alloy; the composition varies with depth. The amount of gold appeared to be elevated in the highlighted regions of the image, whereas shadow regions have lower levels of gold on the surface. The apparent increase in gold within the highlighted region may be due to the larger surface area presented by an array of small image particles. The mercury used to develop the daguerreian image showed no evidence of oxidation while a mercury–silver alloy was detected. Sulfur-based contaminants are also detected. The implications of these findings are discussed.

Characterizing the Image Forming Particles of Modern Ungilded Daguerreotypes Using XRD and SEM

“…For example, electron microscopy, surface metrology, and spectroscopy have been used to study the structure of the daguerreotype and have revealed micro- and nanometer features, and from this, a chemical pathway for the image making process has been proposed (Ravines et al, 2008, 2010, 2016 a , 2016 b ). Recent XPS and XANES studies show that the surface appears to be a gold-silver bi-metallic alloy (Kozachuk et al, 2017 a , 2017 b ). The deterioration mechanisms have also received attention: Raman spectroscopy identified surface corrosion compounds such as silver chloride (Centeno et al, 2008, 2011); sulfur-induced corrosion was investigated with electron microscopy techniques (Marquis Emmanuelle et al, 2015); and secondary ion mass spectrometry (SIMS) and focused ion beam (FIB) SIMS have been used to characterize the surface of this unique object (McPhail et al, 2009).…”

Exploring tarnished daguerreotypes with synchrotron light: XRF and μ-XANES analysis

“…The goal of the present study is to better understand the origin and composition of the tarnish features. This study is part of an ongoing analysis of the surface chemistry of daguerreotypes [11].…”

“…Previous analysis [1][2][3][4][5][6][7][8][9][10][11] has suggested that one possible source of the tarnish could be the deterioration of the cover glass used to protect the daguerreotypes from chemical and/or atmospheric conditions, dust and debris, or from mechanical damage. For example, Barger [12] suggested that deterioration of the cover glass as well as the geometry and composition of the frame might lead to deterioration of daguerreotypes.…”

Imaging the Surface of a Hand-Colored 19th Century Daguerreotype

“…The gilding step was later added by Fizeau, in which the treatment of the daguerreotype with a gold chloride solution increases the contrast and improves the durability of the final image. 1–3…”