The Preservation of Time

The conservators at the Sherman Fairchild Center for Book Conservation at Watson Library examine almost two thousand new acquisitions of rare and artists’ books each year to assess their long-term preservation needs. Of all those books, The Book End of Time (2013) by British visual artist Tacita Dean, is one of the most astonishing. When we first unwrapped the “salt book,” we immediately started thinking about how exactly the artist transformed this book and how we would address the issues of handling and storage for this delicate object representing frozen, precarious time.

Dean created this sparkly, fragile, salt-encrusted artifact by submerging a paperback copy of J. G. Ballard’s futuristic collection The Voices of Time and Other Stories (1962) in a potash evaporation pond in Utah for six weeks. Dean transformed this book as part of her film, JG (2013). In the film, she counterpoints her own correspondence with Ballard with Robert Smithson’s earthwork sculpture Spiral Jetty (1970) to consider narratives of time—geological time, cosmic time, and nature’s time. Dean decided to document the very fragile and seemingly frozen book in a photograph—a poignant statement about the mutual interactions between humans and nature.

When we first unwrapped it, we noticed pieces of crystal sitting at the bottom of the package. This illustrated to us how easily the book could be damaged and raised questions that couldn’t be answered by simply looking, such as: Can this object be touched or moved? How are those crystals attached? Is the paper hardened by the crystal structure, or is it still somewhat flexible? How are the pages held in place? How do you preserve salt?

The first factor to consider is the object’s physical structure. We decided to make a mock-up so we could flex the paper and tap on the crystals without touching the object at all. My colleague Andrijana Sajic found numerous instructional videos on how to grow crystals on all kinds of objects soaked in supersaturated borax solutions. Potash and borax are both chemical salts (sodium carbonate and sodium tetraborate, respectively) forming similarly shaped crystals in warm water solutions. Since borax is easily available and quicker acting (overnight rather than over several weeks) we were able to make some small models of the “salt book”—which made very nice Christmas ornaments, by the way.

We dropped the model into a borax-saturated warm water bath. The absorption of water caused the paper and binding to swell into the shape of an open book, similar to what the “salt book” exhibits. We left the model in the bath as the water slowly cooled (in the Utah potash pool, the water evaporates). As it cooled, the dissolved salt began to precipitate, or fall, onto the swollen book and form crystals.

Examination of the model revealed that the crystals themselves seem hard, and that the thick crust on the exterior seems to be what keeps the pages in place after the book dries. Because they sit on the surface, the crystals themselves don’t seem to affect the flexibility of the paper too much; if the paper is flexed, however, the crystals fall off. Therefore, generally, flexing the paper or touching the object is more likely to cause the crystals to detach from the paper than from each other. To minimize touching, a rigid support, like a tray, was added to the enclosure so the book can be easily moved.

The second factor to consider was the chemical structure. Salt and paper have somewhat conflicting needs when it comes to optimal atmospheric conditions. Watson Library keeps the ambient environment in the stacks at 70⁰F and 50% relative humidity (RH). This is ideal for paper because it needs a moderate supply of water molecules to retain its flexibility. Potash crystals are hygroscopic, which means they attract water molecules. The crystal structure may be affected by atmospheric humidity, causing it to partially dissolve and weaken. If the humidity gets too low, the salt crystals may get thirsty and borrow water molecules from the paper. Storing the “salt book” with silica gel conditioned to 40% RH (+/- 5%) inside a microchamber will help keep all these factors in balance. I added a compartment for the silica gel under the tray, using a shallow “clamshell” box with holes punched in the side. The box is slightly smaller so the tray can easily be picked up at the edges.

To keep the book from shifting inside the enclosure, I added soft, squishy cushions. I sewed four Tyvek covers, stuffed them with polyester fiber, and attached them to collapsible walls. The walls are held up by a cotton tie, which when loosened allows the walls to fall away. This package will be stored inside a box with a pull-down side, so that it can easily slide in without being lifted. A custom polyethylene bag containing the whole box will act as the microchamber and maintain the environment at 40-45% RH.

Untying the enclosure

All the materials used inside the microchamber have been tested for reactive chemicals and stability over time. There are several material tests used in conservation, but we mainly refer to results from Oddy testing (named after William Andrew Oddy, who first developed the test) when evaluating materials suitable for use inside a sealed environment. The Oddy test is conducted by The Met’s Department of Scientific Research in an accelerated aging oven. Small copper, silver, and lead coupons are sealed in a jar with the material being tested and a measured amount of water to maintain a high humidity. The jar is placed in the oven at 60⁰ C (140⁰F) for about one month. The high humidity and temperature simulate the environmental conditions endured over many years. When the jar is removed, the coupons are examined for signs of corrosion. Corrosion is an indicator that there may be acidic or sulfuric compounds present in the material that are harmful to books or museum objects sealed in a microchamber.

The microchamber itself is simply a sealed bag. I made a custom bag to fit this box using a plastic edge-welding machine because it’s hard to purchase just one bag of any size. Polyethylene was chosen as the material because it is accepted, through material testing, as a clear, impermeable, and stable plastic film. The bag is rolled on one side so the box can be slid out, rather than lifted out from the top, and clipped so it’s easy to reseal after opening. Directions on how to remove the box from the bag, and the object from the box, are be seen through the clear plastic.

When this book is requested at the circulation desk at Watson, there is a note in the record that Conservation staff should assist with unwrapping and rewrapping it for viewing. For now, to the best of our ability, we have stalled time inside this chamber to preserve frozen time for the future.