Apr 272015
 

 

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.

Dr. Dale T. Mortensen (1939-2014) won the 2010 Nobel Prize for economics and is known for his work on labor economics and frictional unemployment. He taught at Northwestern from 1965 to 2011. After Dr. Mortensen’s death in 2014, his chalkboard was removed from the wall of his office on campus. It is included in his archive – along with documents, correspondence, computer files, and other personal effects – as a physical manifestation of his process.

Dale Mortensen's chalkboard awaits treatment in the conservation lab after having been removed from his campus office.

Dale Mortensen’s chalkboard awaits treatment in the conservation lab after having been removed from his campus office.

Before the chalkboard could be stored in University Archives, a method needed to be devised to affix the chalk to the board so that the unbound media would not dust off. Special Collections Conservator Susan Russick researched various adhesives and application methods to determine the best one to keep the chalk in place. Funori, an adhesive made from Japanese seaweed, was chosen based on its good aging properties and the fact that it dries matte, thus retaining the visual aesthetic of the chalkboard.

Funori in three forms: dried seaweed, purified as a film, and rehydrated in solution.

Funori in three forms: dried seaweed, purified as a film, and rehydrated in solution.

To prepare the funori, 6 g of dried seaweed was rinsed and then soaked in 200 ml water overnight. The funori-water mixture was heated to just below simmer for about 90 minutes and strained through a silkscreen fabric. The resulting viscous liquid was dried on silicone coated Mylar, resulting in a translucent film. The funori film was stored dry and later reconstituted to a 0.5% solution by warming in deionized water.

A John Bunn Neb-U-lite EV™ machine, normally used for delivering medicine for respiratory ailments, was used to apply warm funori as a mist to the chalkboard. This very delicate application method was the only one found that did not disturb the fingerprints, erasure marks and smears of chalk.

In this brief video, Susan applies a layer of funori to one chalked letter using the nebulizer.

 

After treatment, Dr. Mortensen’s fingerprints and smudges are still visible on the surface of the chalkboard.

After treatment, Dr. Mortensen’s fingerprints and smudges are still visible on the surface of the chalkboard.

Multiple coats of funori were applied as a mist, each taking up to 15 hours to apply. The chalk still looks like just chalk – not shiny or slick – and without drip or brush marks. The chalk could still be removed if directly rubbed, but is now well adhered enough to tolerate the vibrations of being placed on a cart and moved for storage.

Mortensen_AT23

Chalkboard in custom-made box.

 

Mortensen_AT26

Detail of fall-away walls.

To prevent the chalk surface from being touched in storage, a special box was fabricated using Tycore® board, foam and cloth. The box grips the chalkboard around the aluminum edges using fold-away “load bearing” walls. Even if the lid warps a bit, it will not touch the surface of the chalkboard and Dr. Mortensen’s notes will remain intact for future scholars.