Apr 302015
 

 

This spring, the Northwestern University Library Preservation Department curated the exhibit “Beyond the Book: The Changing Nature of Library Collections,” which highlights some of the Library’s rare and interesting objects that have received conservation attention in the past few years. In celebration of Preservation Week (April 26 – May 2, 2015), the blog will feature daily posts highlighting exhibit objects that posed some of the more complex research questions and interesting treatment decisions.

When this animation cel from Walt Disney’s 1939 The Ugly Duckling was brought to the attention of the Preservation Department, the duckling (spoiler alert: cygnet) and frog characters had detached from the background illustration and were floating loose behind a layer of warped and yellowed plastic.  The cel packet was taped to the signed mat using both water soluble and pressure sensitive (sticky) tapes.

An investigation of the materials used for animation cels reads like a horror novel to a conservator. Recent research about animation cels done by the Getty Conservation Institute and the Disney Animation Research Library has shown that the plastic films from this time period are most likely cellulose nitrate or cellulose diacetate.   Both of these films yellow, distort and become brittle as they age. The uneven shrinkage is especially bad because the inks attached to the films do not shrink at the same rate, often resulting in the media flaking off of the film. The watercolor background was painted on an acidic board and the adhesives used to attach the duck and frog have failed and discolored. In other words, treatment options to repair the object that involve water, solvents, heat or pressure are prohibitively risky due to the likelihood of paint and ink bleeding or flaking and the plastic film fogging, dissolving or cracking.

Conservation treatment recommendations have not yet been well established for these materials, so a very cautious approach was taken. In order to preserve the look of the original art with minimal disturbance to these fragile materials, Special Collections Conservator Susan Russick encapsulated the duckling and frog characters between two sheets of polyester film. The characters are positioned properly in relation to the background and held in place with microdots created using an ultrasonic welder.

Ultrasonically produced microdots seal the two layers of polyester film together in several spots surrounding the duck.  Two dots are visible on either side of its neck and a third is seen between the wing and the foot.

Ultrasonically produced microdots seal the two layers of polyester film together in several spots surrounding the duck. Two dots are visible on either side of its neck and a third is seen between the wing and the foot.

Ultrasonically produced microdots seal the two layers of polyester film together in several spots surrounding the duck. Two dots are visible on either side of its neck and a third is seen between the wing and the foot.

The encapsulated characters were placed in a window mat that holds them relatively flat but will allow some movement of the brittle film as deterioration continues. This non-adhesive window mat sits invisibly between the original signed Disney mat and the background illustration. The polyester film provides some level of protection to reduce interaction between the acidic background and the degrading film. No solvents, moisture, heat or pressure were used and the appearance of the object is similar to the original.

Like all conservation treatments, the decision to proceed with this one was made after careful consideration of the risks and benefits by the Special Collections Curator and the conservator. This solution is not perfect. Polyester film carries a static charge which could exacerbate paint flaking and the object format was significantly altered. While some risks remain, the many restrictions dictated by the materials of the object made this the preferred and most cautious choice in our efforts to slow degradation and preserve the object.   Although our duckling (cygnet) may never turn into a swan, we hope to prevent it from turning into a toad.

 

Apr 282015
 

 

This spring, the Northwestern University Library Preservation Department curated the exhibit “Beyond the Book: The Changing Nature of Library Collections,” which highlights some of the Library’s rare and interesting objects that have received conservation attention in the past few years. In celebration of Preservation Week (April 26 – May 2, 2015), the blog will feature daily posts highlighting exhibit objects that posed some of the more complex research questions and interesting treatment decisions.

Cuneiform script is one of the earliest known systems of writing, first developed in Mesopotamia c. 3400 BCE. A blunt reed was used as a stylus to press wedge-shaped marks into clay tablets. The Library’s collection of 17 cuneiform tablets, available in the Charles Deering McCormick Library of Special Collections is frequently shown to students as examples of early writing technology, but until recently little was known about these particular tablets.

Cuneiform tablets must be viewed in raking light to read the text.

Cuneiform tablets must be viewed in raking light to read the text.

There is little provenance available related to these tablets and at least two different incomplete and overlapping numbering systems were previously used. In order to establish authority over the collection, a new numbering system was developed. The new numbering system needed to be distinct from the old numbers, but without obscuring either the old numbers or any of the cuneiform writing. It needed to be small, legible, easy to apply to a bumpy surface, and not damaging to the tablets.

Two tablets marked “5” in the previous numbering systems.

Two tablets marked “5” in the previous numbering systems.

NUL Special Collections Conservator Susan Russick, while specializing in book and paper conservation, has some experience with archeological materials. As a summer intern, she worked with ceramic materials of a similar age at the Gordion Archeological site in Turkey. After some consideration, each tablet was given a tiny paper label. Labels were laser printed on archival paper and adhered using Acryloid-B72, a method described by Thomas Braun, who was also at Gordion that summer.

Tablets in box

A box with foam sockets and removable trays was constructed, allowing the tablets to be viewed and passed around the classroom without being directly handled.

Tablet in box with label

The individually labeled sockets aid in security of the tablets.

Digital images of the tablets were submitted to the Cuneiform Digital Library Initiative, an international group of Assyriologists, curators, historians, and librarians working to make available online over 500,00 cuneiform tablets. Northwestern’s participation in this effort will allow our collection of tablets to be viewed, studied, and translated by scholars around the world. As an initial result of this collaboration, we have learned that the majority of our tablets are accounts from the 21st century BCE and a few are neo-Babylonian texts.