Wallace Conservation Lab

Posters, posters, and more posters!

A recent donation of several hundred movie posters (not all are shown above) recently invaded the conservation lab. The posters had been rolled for storage, and while a few unrolled easily, those printed on heavyweight paper didn’t want to be flat.

I knew that trying to humidify and flatten each poster individually would drive me to the brink of insanity (and take a long, long time), so I did some research and found a great article by Stephanie Watkins in the Book and Paper Annual, entitled Practical Considerations for Humidifying and Flattening Paper.

Following the description in the article, I covered our drying rack in plastic sheeting and hooked up our ultrasonic humidifier in the back.  This pumped in cool, moist air.  I placed a thermometer/hygrometer inside the improvised chamber to monitor the temperature and humidity.

Once the posters were nice and relaxed, I removed them from the chamber, and placed them between hollytex and blotter to dry.

Using this method, I was able to humidify and flatten dozens of posters in only a few days - and kept my sanity!

Summer is my favorite time to humidify and flatten books since the relative humidity is usually a bit higher and can help things along.

Many vellum books in our special collections have become badly warped over time.  After flattening, they are boxed to prevent them from becoming warped in the future.

- Bexx

I recently finished conservation of a 6 volume set of vellum bindings.  The covers were badly warped, turning the books into wedge shaped shelving problems. 

Before treatment, the entire set measured 998 millimeters wide.  That’s a lot of shelf space!

After humidification and flattening of the covers, the 6 volume set is a svelte 197 millimeters!  The photos above show just how much space that saved!

- Bexx

Recently, I treated a very large map that was in very bad shape.  It was printed on poor quality paper, and then backed with linen to add strength.  It had been tightly rolled, and was curled and cracking in numerous places.  To make matters worse, it was filthy and had suffered water damage.

After gently unrolling the map, I carefully surface cleaned it.  I wasn’t able to clean it as thoroughly as I would have liked because the paper was flaking away from the backing.  Next, I used our Preservation Pencil to humidify curled or creased areas, repairing and flattening as I went.  Only the worst tears were repaired, and flaking bits were re-adhered with Lascaux 498HV (paste would have caused stains). It was a long an exhausting day’s worth of work!

Finally, I worked with Eric and Autumn to move and encapsulate the map in Mylar.  Since the map is too large to fit into a flat file, it was rolled onto a 6″ tube for storage.

Although the map is still in very poor condition, it can now be used and stored.  safely.

- Bexx

This poor vellum book was severely warped.  Before humidification and flattening, it measured a hefty 113 mm thick - afterwards, a mere 67 mm.

That’s almost 2 inches!

Vellum is a hygroscopic material, which means that it has the ability to attract and hold water molecules from the surrounding environment. 

Vellum will expand in humid conditions, and contract in dry conditions.  Even normal fluctuations in temperature a humidity can cause vellum bindings to warp.  Over time, this book became badly warped.  At it’s thickest, it was a whopping 70 mm (2.75 in) thick.

I gently humidified the front and back covers to help them relax  - you need be careful when exposing vellum to water - too much, and it can turn back into rawhide!

Once the covers had relaxed, I put the book under weight to flatten it out.  I left it that way for about a week - plenty of time to dry and become accustomed to being flat.  After treatment, the book was a mere 46 mm (1.8 in) thick - that’s a reduction of 24 mm (.94 in)!

To help keep the book flat, it has been housed in a custom made box that keeps it under light pressure.

Find this book in our Special Collections here.

~ Bexx