TREATMENT on the Great Parchment Book

Part 1

With all the tests we have carried out we are now ready to start to work on the Great Parchment Book!

Surface cleaning

Prior to humidification surface cleaning is being carried out using vulcanised rubber sponges and soft goat hair brushes. The sponge works by picking up and drawing in the dirt when it is placed in contact with the surface of the object to be cleaned. With the Great Parchment Book, ideally, we would like to remove as much surface dirt as possible from the parchment to stop it being drawn into the substrate when it absorbs moisture during humidification. Also, it helps to improve the legibility of the text. However, where flaky media is present, surface cleaning has to be avoided as the sponge will pick this up too.

Area before cleaning

Area after cleaning

The ink on the sample above is very stable and so the area could be cleaned. The sponge was most effective on the area in the middle, where the dirt was sitting loosely on the surface. However, the dirt in the bottom right hand corner of this image was much more ingrained, and so surface cleaning did not improve it.

Treatment trials continued… (part IV)

17^th-century samples with original fire damage

An original sample of heat damaged parchment (not part of the LMA collection) was found, and the magnet drying system was tested again. This was a good sample to test the treatment on as it had similar planar distortions and fragile edges as seen on the Great Parchment Book, which would not withstand having clips attached. (The sample was fully humidified between blotter and Gore-Tex®.)

Before	After
Close-up before	Close-up after

Results

This method worked really well. Stronger, larger magnets were used around the shrunken areas to help hold the creases open, and then weaker, smaller ones were used to hold down the torn, fragile edges. However some tears, that were already present, did become wider and more obvious. This was a natural reaction to the overall plane of the parchment becoming flatter, but should be avoided when treating the Great Parchment Book.

Virtual flattening

Alongside all the conventional conservation work happening on the book, here at UCL we are experimenting with ways to “virtually restore” the book using a mix of imaging, computer vision, and computer graphics techniques.

Our approach is two-fold. First create a virtual 3D model of each page, and second flatten the 3D model into a 2D plane. It sounds fairly simple but is deceptively complex.

Creating detailed models of the pages requires a careful imaging process to try to get inside every crease and fold and capture every letter at as high a resolution as possible. The result is a set of 50 or so high-resolution images (for each page of the book). These are fed into a pipeline of computer programmes which (after a considerable amount of processing time) generates the 3D model.

Before virtual flattening

3D mesh

Then comes the problem of flattening the page in a sensible way. At first glance, it would seem that we want to just “unfold” the page as you would a crumpled piece of paper. However, the way the pages are distorted is not like crumpling a piece of paper and so there is no nice and easy way to “unfold” them. So now the problem becomes “how can we flatten the page into a 2D plane in such a way that the text does not become distorted”, and that is what we are trying to solve at the moment.

After virtual flattening