Recovering Past Reflections: X-ray Fluorescence Imaging of Electrocleaned 19th Century Daguerreotypes

Abstract

The first commercially viable photographic image, the daguerreotype, captured images for a span of approximately 20 years . DeDterioration now disfigures many of these valuable images. One proposed restoration method is an electrochemical process. However, its safety and effectiveness are still under debate within the conservation community as the effects of this treatment, and its physical and chemical impact on the daguerreotype image, have not yet been analyzed in depth. This study used synchrotron-based micro-X-ray fluorescence to map the elemental distribution pre-and post-electrocleaning on 19th century daguerreotypes using both soft and hard incident X-rays. X-ray absorption spectroscopy was used to probe local chemistry before and after cleaning. Two different electro-treatment methods were compared: the original method proposed by Barger and a second put forward by Wei. When used correctly, both processes significantly reduced the S and Cl surface contamination without dulling the surface. However, both electrochemical methods used in this study resulted in a loss of Hg and Au from the surface. In all cases, the Hg distribution tracks with image particle density allowing the retrieval of full portraits from entirely corroded daguerreotypes, suggesting that Hg concentration may be a useful proxy for the original image.

The Degradation of Daguerreotypes and the Relationship with Their Multi-Material Structure: A Multimodal Investigation

“…Other vibrational sensing, through attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), has limited applicability due to the required sampling or direct contact with the material [19]. Imaging methods, such as technical photography (ultraviolet (UV) and visible) hyperspectral reflectance and XRF mapping, focus mainly on the daguerreotype plate [10,17,18,20] to register its characteristics [11,[21][22][23]. In this respect, we propose a comprehensive non-invasive, multi-sensorial protocol to examine the complete multi-material structure of daguerreotypes at a microscale, with special regard to the corrosion products.…”

Exploring the Dzi Bead with Synchrotron Light: XRD, XRF Imaging and μ-XANES Analysis

“…Using a micro-X-ray beam, we can conduct microscopy and microanalysis of the different patterns of the specimen. We have gained considerable experience over the years in the research and development of these techniques [9] and are encouraged by our recent success in retrieving high-resolution images from badly tarnished daguerreotypes [10][11][12], the first public photographs in human history. The applications of X-rays from synchrotrons in art and archaeology have also been reviewed recently [13].…”