Thursday, September 20, 2012

Desiccant Wheels

As a book conservator I was trained to dis-bind, wash, mend and re-sew books from different points in history.  However, a library's storage environment also plays a crucial role in the longevity of collections.  There's little to be gained from spending hours and hours treating a rare book if you have to send it back to a stacks area that is not up to par.
Facilities staff will always have the primary responsibility for maintaining the air handling systems, but it is important that librarians are engaged and articulate about the systems that take care of their books.  So a significant portion of my training focused on building systems, including heating, ventilating and air-conditioning (HVAC).  We had a final workshop on HVAC systems that reviewed different types of HVAC technology and concluded with a walk through of the air handlers in our classroom building. 

One of the technologies that was new at the time (1998) was using a desiccant wheel for de-humidification.  Have you noticed the little silica packets that come in boxes of shoes or electronics?  They're like that but much, much bigger.   

All of the buildings I've worked in 'til now have been older buildings with older types of HVAC systems.  My current job has been my first opportunity to see a desiccant wheel up close and I must say it was pretty exciting.  You can gete a sense of how big the wheel is from the picture above.  The yellow strap is the drive belt for the wheel, to keep it turning so that the unsaturated section of the wheel is in the airflow from the building while the saturated part is getting dried out. 

The wheels do get changed when they wear out as you can see below.  They're very, very heavy, so it is a good thing they roll.

Thursday, September 13, 2012

Mathew Brady's Civil War photographs

Mathew Brady is probably the most famous photographer associated with the American Civil War.  The UVa Small Special Collections Library has a small collection of the photos, mounted on individual cards.

The photos are kept in climate controlled storage, but the box they were in was a little too big and allowed the photos to warp.

Not good.  But fixable!
First, the photographs are humidified between two layers of Gortex, to relax both the cardboard and photograph layer.
Then it is time for my old favorite technique, the "back and wrap" which is great for stabilizing individual items.  The flattened photograph is placed on a piece of mat board that is slightly larger.  Since each photograph is labeled on the back with the number and title of the photograph, plus Brady's copyright warning, I photocopied the backs of the photographs, cut out the labels and adhered them to the back of the mat board.  I also wrote the call number on each one.

The photo and mat board are placed face down on a piece of Mylar and the corners of the Mylar are trimmed away. 
The Mylar is wrapped around the edges of the board and secured with double stick tape.  A neat package that buffers the photograph from environmental shifts, provides enough stiffness to keep the cardboard from warping, and the Mylar protects the photograph from scratches, fingerprints and dust.

A neat little package that makes it possible to handle the photographs more safely!