Characterization and Restoration of 19th Century Daguerreotypes

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DOI: 10.1017/S1431927607079627
Microsc Microanal 13(Suppl 2), 2007
Copyright 2007 Microscopy Society of America
Characterization and Restoration of 19th Century Daguerreotypes by SEM,
XEDS and FIB
Elise A Gregory*, Cathy Selvius DeRoo** and John F. Mansfield***
*Department of Chemical Engineering, University of Michigan, 2300 Hayward Street, Ann Arbor,
MI 48109-2136
**Detroit Institute of Art, Detroit, MI
***North Campus Electron Microbeam Analysis Laboratory, University of Michigan
2455 Hayward, Ann Arbor, MI 48109-2143
The daguerreotype was named after the French artist and chemist Louis J.M. Daguerre who, in
collaboration with the inventor Nicéphore Niépce developed this first successful form of
photography in the 1830s [1-3]. Once Daguerre had perfected the process in the early 1840s, this
process became a popular technique for portraiture, until it was replaced by the wet collodion
process towards the end of the nineteenth century [4].
To produce a daguerreotype, a highly polished, silver-clad copper plate is exposed to iodine and
bromine vapor, creating a light-sensitive, mixed silver halide layer. Exposure of the sensitized plate
to light causes a photodecomposition process, resulting in the formation of metallic silver particles
on the plate surface: the latent image. The plate is then developed by exposure to mercury vapor,
which results in the formation of silver mercury amalgam particles. The amalgam particles constitute
the image highlights and are of sufficient size to produce the visible image. The darkest areas on the
developed plate are due to areas of polished silver surface with a low surface density of lightdeflecting amalgam particles The image is fixed with sodium thiosulfate to remove the residual
silver halides, rinsed with water, and subsequently gilded using a solution of gold chloride or gold
thiosulfate. The gilding helped the silver mercury amalgam particles to adhere to the plate and also
improved image contrast.
Unfortunately, daguerreotypes do not age well unless kept in strictly controlled environments, which
most museums now do. The Smithsonian’s National Portrait Gallery, for example, has over 110
daguerreotypes in its collection. However, many of the images have suffered from exposure to the
atmosphere and show varying amounts of discoloration and numerous blemishes. While there have
been a number of attempts to study the chemistry and morphology of the corrosion and tarnish, there
is no systematic study of the various phases and compounds that form on the daguerreotype surface
during aging and how they affect the appearance of the image [5-8]. Additionally, there has been
little study, to date, of the feasibility of selectively removing the corrosion products to restore the
quality of the image.
The aim of this project is to identify the various different corrosion products that exist on
daguerreotypes, and to determine whether they maybe selectively removed by either a focused ion
beam or by ultrafast laser ablation. The sample daguerreotype chosen for study (see Fig. 1), shows a
considerable amount of discoloration across the whole surface. Initial studies focused on the region
of the right eye, as outlined in Fig. 1. Fig. 2 shows the eye at higher magnification. The small black
dots on the optical image, which appear white on the SEM image, are determined to be part of the
brownish cast that is seen in the center of Fig. 1. XEDS maps of these features reveal that they are
copper rich islands (see Fig 3.). The origin of these features is under investigation.
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Microsc Microanal 13(Suppl 2), 2007
References:
[1] daguerreotype. (2007). In Encyclopædia Britannica. Retrieved February 26, 2007, from
Encyclopædia Britannica Online: http://search.eb.com/eb/article-9028530.
[2] Daguerre, Louis-Jacques-Mandé. (2007). In Encyclopædia Britannica. Retrieved
February 26, 2007, from Encyclopædia Britannica Online: http://search.eb.com/eb/article-9028529.
[3] Neblette, C. B. (2007). Daguerreotype. Encyclopedia Americana. Retrieved February 26, 2007,
from Grolier Online http://ea.grolier.com/cgi-bin/article?assetid=0117570-00.
[4] wet collodion process. (2007). In Encyclopædia Britannica. Retrieved February 26, 2007, from
Encyclopædia Britannica Online: http://search.eb.com/eb/article-9076702.
[5]Hogan, D.L., V.V. Golovlev, M.J. Gresalfi, J. A. Chaney, C.S. Feigerle, J.C. Miller, G. Romer,
and P. Messier. Laser ablation mass spectroscopy of nineteenth century daguerreotypes. Applied
Spectroscopy 53 (1999): 1161-1168.
[6] Daffner, L.E., D. Kushel, and J.M. Messinger. Investigation of a surface tarnish found on 19th century daguerreotypes. Journal of the American Institute for Conservation 35 (1996): 9-21.
[7] Barger, S.M., and W. B. White. The daguerreotype: nineteenth century technology and modern
science. Washington, D.C.: Smithsonian Institution Press, 1991.
[8] Swan, A., C.E. Fiori, and K.F.J. Heinrich. Daguerreotypes: A study of the plates and the process.
Scanning Electron Microscopy 1(1979): 411-23.
a.
b.
1.0 mm
9 mm
Fig. 1. Image of whole daguerreotype,
subject unknown. Red box marks
analysis area in subsequent Figs.
BSE
Ag
Fig. 1. Image of right eye. (a) optical,
(b) SEM. Note the lines of features to
the right of the angled line
Cu
100µm
Fig. 3. SE and XEDS images of dark islands near the figure’s eye. Surface
is predominantly silver rich and the islands are copper rich.