Preserving Our Treasures

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The Museum’s conservators have rehoused its two prized daguerreotypes by Southworth & Hawes. [Two women posed with a chair], going on view this June, and [Child, asleep, with one arm raised] (both ca. 1850) were acquired in 1999. They came to the museum each in a modern displayable package that consisted of glass glazing, a mat board spacer, the daguerreotype, and mat board backing; a package in which they were housed until recently.

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Rehousing the daguerreotypes gave Sylvie Pénichon (Photograph Conservator) and Tatiana Cole (Fellow in Photographs Conservation) the opportunity to fully examine and document the condition of the bare daguerreotype plates under different types of illumination and under magnification. Some of which are described below.

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Coaxial illumination (above left) allows for imaging of surface characteristics of a daguerreotype (above right) without distracting reflections from its mirror-like surface. Illumination with ultraviolet light can sometimes reveal residual chemistry, for example from initial processing of the image or previous treatment, and it can also show the presence of degradation products. However, examination under ultraviolet light revealed none of the above on the Museum’s two daguerreotypes.

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Photomicrographs, i.e. images taken under magnification (as shown above), allow conservators to closely monitor any possible changes experienced by the delicate image material of the daguerreotype, which is composed of microscopic silver and mercury amalgam particles often coated with gold. One common type of degradation is characterized by a nucleus surrounded by a white haze (below left). Fingerprints perhaps belonging to the photographer himself may also be found (below right).

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Photomicrographs also help to record hallmarks, which are blind stamps that identify the plate manufacturer or photographic supply house, and hold extremely useful information for researchers. A number, such as the “40” shown below, refers to the amount of silver to copper present in the daguerreotype plate. The particular hallmark shown below (from [Child, asleep, with one arm raised]) also identifies the plate as one of the most widely used French plates available between ca. 1850-1858.

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After detailed documentation and imaging, the daguerreotypes were safely rehoused between two plates of highly stable and optically clear borosilicate glass, with a polyester tray that borders the daguerreotype plate (below left). The tray acts as a spacer that prevents direct contact between the delicate image surface and the glass. The glass on both sides gives researchers visual access to both the front and back of the daguerreotype plate. It also minimizes the amount of hygroscopic (moisture loving) materials, such as mat board, present within the package. Lastly, special tape is used to bind the new package components together. A schematic diagram shows a cross-section of the new housing (below right).

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With new sealed packages, proper exhibition and storage conditions, and close monitoring by conservators, Southworth & Hawes’ exquisite images will be preserved for generations to come. Be sure to come see [Two women posed with a chair] on view this coming June.

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