Lewis M. Rutherfurd, Detail of Moon, 4 March 1865. Albumen silver print, 57.3 x 44.2 cm. Purchased 1999. National Gallery of Canada, Ottawa Photo: NGC

Dark Side of the Moon: Forensic Analysis of Lewis M. Rutherfurd's "Moon"

Lewis M. Rutherfurd’s Moon is an albumen silver print that the pioneering astrophotographer produced in 1865 by attaching his photographic apparatus to a telescope in order to capture the surface of the moon. The work was possible because of the recent development of the dry plate process which enabled the faster capture of an image. In 1872 he presented the resulting set of impressively sized and detailed albumen silver prints to the Académie des sciences in Paris in an effort to persuade the academicians of the effectiveness of using photography to record the planets. Moon is an important example of the use of the photographic medium for scientific purposes and, acquired by the National Gallery of Canada in 1999, is currently on view in the Canadian Photography Institute’s exhibition The Extended Moment: Fifty Years of Collecting Photographs.

Lewis M. Rutherfurd, Moon, 4 March 1865. Albumen silver print, 57.3 x 44.2 cm. Purchased 1999. National Gallery of Canada, Ottawa Photo: NGC

As part of the standard preparation for an exhibition, Rutherfurd's photograph needed to be examined by the Restoration and Conservation team in the Gallery's Prints, Drawings and Photography conservation laboratory. For an exhibition of this magnitude – which includes 175 artworks from all eras of photography in the Institute’s extensive and diverse collection – the range of conservation requirements can vary as much as the artworks themselves. The role of the Photographs Conservator is to prescribe and execute appropriate treatments such as repairs and surface cleaning, while the Conservation Technician carries out preventative conservation and maintenance. Both have the same objective: the safe and appropriate display method for every object in the exhibition.

Rutherford's Moon - the left image was taken under studio lighting, and, on right, under ultraviolet light. The left image shows the object as it was previously mounted using two linen tape T-hinges along the top and two corner mounts at the bottom; the right image shows the object lifted up and out of its corner mounts. Photos NGC


As is typical for the albumen photographic process – by which an egg white mixture is fixed onto a very thin, high-quality paper and made light sensitive with a silver nitrate solution – the finished print is adhered to a larger and thicker paper support to help protect the print against distortions and handling damage. These two elements – the print and the support – make up Rutherfurd’s Moon, also referred to as the ‘object’ or ‘artwork’. During our assessment of Moon’s conservation needs, we noted that the print itself is in very good condition, especially considering its age: Aside from some characteristic yellowing, silver mirroring and small surface abrasions, nothing about its condition is out of the ordinary. However, we also noted some damage on the back of the support that had been the result of the artwork’s display history prior to acquisition.

The support of the object , showing fingerprint, yellowing and moisture damage. Photo NGC


Some of the alterations to the support, such as the fingerprints, overall yellowing and moisture damage are quite common in 19th century photographic collections. What was unusual were the woodgrain-like patterns of acid damage over the back of the support, as well as the line of skinning caused by insects having eaten away at the surface.

The back of the support seen under studio lighting at left and, at right, under ultraviolet light. Photo NGC


The artwork's condition had been meticulously documented and photographed throughout its time in the collection and the damage to the back of the support had been noted initially in August 1997, when the work was examined before being acquired by the Gallery. In his treatment recommendations, the then Photographs Conservator suggested the print could remain attached to the support as the overall object was stable despite the observed acid and pest damage. In our latest assessment, we ascertained that at some point in its lifetime, this object was in direct contact with a piece of wood for an extended period of time. The most likely scenario is that a sheet of wood was used as a backing board in a display frame. Over time, and exacerbated by a humid environment, acid from areas of the wood that were in direct contact with the back of the object migrated into the support’s paper fibers, and the resulting deterioration caused a ghost-like wood-grain pattern of discolouration.

Close-up of acidic migration damage on the support. Photo NGC


The insect damage is undoubtedly the work of silverfish (Lepisma Saccharina), a small, wingless species that thrives in damp environments. Subsisting predominantly on a variety of plant-based materials, silverfish love to eat paper. They do so by grazing haphazardly, anywhere that they can conveniently access the paper surface, leaving behind a very characteristic pattern of damage. In this case, because the damage is localized along a single horizontal line, we can assume that something was restricting the silverfish from having full access to the support at the time of the infestation.

It is likely that the backing board was actually made up of two separate pieces of wood and it was the gap between them that allowed the insects to eat away at the support. Given the evidence that the silverfish were eating fibers already darkened by acidic migration, we can assume that the infestation happened after the discoloration had started. Since Silverfish thrive in a damp environment, we know that the infestation happened while the work was housed in a place with no humidity control systems.

Close-up of Silverfish damage on the support. Photo NGC


The inherent danger to the artwork – both the support and the print – was eliminated when the wood backing was removed and the infestation was dealt with. As the paper support is fairly thick and the acid and pest damage on the back is only a few fiber layers deep, neither of these deteriorations affected the print on the front. The object continues to be stable and the condition of the print itself is very good. Since its acquisition, Moon has been kept in an acid-free enclosure in a temperature- and humidity-controlled storage vault with environmental and pest monitoring. This is why the Gallery's conservators have continued to come to the same conclusion: removing the print from its support is possible, but not necessary.

As a rule, any treatment or repair that a work of art undergoes must be reversible, but there are occasional exceptions. The decision to separate the print from its support would be weighed carefully, as this kind of treatment is not considered 100% reversible. The support is a part of the artist’s original work of art, and despite the damage, the object’s overall condition does not warrant any intervention at present. This may change at some point in the future, however, which is why this work of art will continue to undergo regular examinations in order to monitor and document any changes to its condition.

Rutherfurd’s photograph is a good example of why preventive conservation is a critical practice in collections care: it is a big part of why objects can last for so long, even after sustaining certain forms of irreversible damage. The Gallery has environmental controls that regulate temperature and relative humidity throughout the exhibition spaces, storage vaults and work areas. We use stable, acid-free materials for all storage enclosures and, as part of lending to exhibitions, we use materials and techniques that safeguard works of art against the mechanical stresses and environmental changes of installation and transit.

Installation view of the Extended Moment exhibition, showing Lewis M. Rutherfurd's Moon; as well as Wilson A. Bentley, Snow Crystal No. 3070, 6 February 1918; Snow Crystal No. 4271, 2 February 1924; Snow Crystal No. 2010, 31 March 1911 and Snow Crystal No. 3837, 17 December 1922. All gelatin silver print. Purchaed 1996. National Gallery of Canada, Ottawa Photo; and Eadweard Muybridge, Jumping, Running, Straight High Jump, c. June 1885–11 May 1886, printed November 1887. Collotype. Gift of Mrs Virginia P. Moore, Ottawa, 1981. Photo NGC


Rutherfurd’s Moon – housed at the Gallery in an ideal environment away from acidic materials, pests and dirty fingertips – is stable. Moon now hangs among the 175 photographs on view in The Extended Moment, marking its significance in the evolution of photography from its very beginnings to today.


The Extended Moment: Fifty Years of Collecting Photographs, organized by the Canadian Photography Institute of the National Gallery of Canada, is on view until September 16, 2018. The accompanying fully-illustrated catalogue is available at the Gallery's online Shop at  ShopNGC.ca. To share this article, please click on the arrow at the top right hand of the page. Subscribe to our newsletters to stay up-to-date on the latest Gallery news, and to learn more about art in Canada.​

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