Science Interviews

Interview

Tue, 19th Nov 2013

There's something fishy in the library

Lucy Cheng, Rebecca Goldie and Mary French, Cambridge University Library.

Listen Now    Download as mp3 from the show Restore, repair, retain!

Restoring a 40-year old film is one thing, but what about documents that are Vellum Manuscripthundreds of thousands of years old? Matt Burnett went to the Cambridge University library to see how they repair ancient documents. Rebecca Goldie told him how they categorise the fragility of the manuscripts when they arrived.

Rebecca - The collection that I'm working on actually arrives more in fragments. As you can see, they're kind of torn up. They've been eaten by insects. They've still got dirt on them from Ė well, some of them were found in cemeteries...

Matt - They're all kind of falling apart in their various states. Some of them just have little holes and other ones are literally being stuck back together. How do you determine what kind of work needs to be done on each of the fragments?

Rebecca - We need to assess the stability of the inks, seeing as what the text says is what's most important for researchers. In order to do that, we look at the inks under a linen tester which is like a tiny microscope and we give it a category of 1 to 3 where one is a stable ink and 3 is a really bad one. This is an example of one which is category 1 where we place the linen tester over the ink and use a sable hair brush over it. As you look through, you will see the ink doesnít move.

Matt - I'm looking through what's basically like a mini microscope. I can see that as Rebecca brushes over it, a bit of the dust is being removed, but the letters are sticking onto the paper just fine. So, that's a level 1.

Rebecca - That's 1. We donít need to worry about that, we can go through conservation without worrying that weíre going to destroy it. Category 3, if we just gently brush across it, we might actually brush away some of the ink and that means that the rest of the conservation process could potentially damage the fragment.

Matt - What methods can you use to conserve this without damaging the writing?

Rebecca - First of all, we would try to see if it was possible to clean it under magnification. However, if this just seems like itís not going to work and is going to cause further damage then we put the fragment aside for ink consolidation.

Matt - Ink consolidation makes sure the writing remain stuck to the most delicate level 3 manuscripts. Lucy Cheng has been working on a method to conserve these fragile letters.

Lucy - We have researched into various consolidant and the result reveals that isinglass might be one of the possible solutions. Isinglass is an adhesive and in a lower concentration, it could be used as a consolidant. Itís known to be tacky. It works at a lower viscosity. What we like about it is that itís also chemically inert with the pH value of 6 to 7.

Matt - So, I can see here on your desk, you've got a funny looking packet full of Ė well, it looks like some exotic food. Is this isinglass?

Lucy - This is isinglass. So, isinglass is basically made from the bladder of a sturgeon. Basically, the fish were prepared in such a way that the bladder is separated, cleaned and dried. This is what you see in front of you.

Matt - You've got a big jar of little glass discs.

Lucy - Our plan is to run the solution through an ultrasonic mister and mist a solution onto the text area. The hope is that the tackiness of the solution would help the ink resettle onto the paper.

Matt - Okay, so you're basically spraying this very gentle adhesive over the old manuscripts and itíll stick the words down to the paper and then at that point, you can further clean them all or repair the manuscript if needs to be.

Lucy - Exactly.

Matt - Even after sticking the ink back down, there's often further work that needs to be done. For example, folds in the parchment can make the text illegible. Mary French explained how these folds can be ironed out without damaging the fragments.

Lucy - One thing that we do typically, especially where the folds obscure text is that we can humidify them and then unfurl them and press them flat, so, the text can be revealed and the objects can lie flat. One way in which we do that is with the use of agar. Itís derived from marine vegetable, itís usually red algae.

Matt - Itís just the same stuff that I used in my microbiology degree.

Lucy - Yeah. One the interesting things about conservation is that we are able to use materials that come from a variety of disciplines Ė I guess the word would be. So, this piece right here was initially folded over. These at some point have been humidified and then press flat, and certain areas have been folded over remained that way once it had been pressed. It was probably about 100 years ago.

Matt - This is a pretty large fragment that weíre looking and itís got some impressive holes in. What was the state of this when you first got your hands on it?

Lucy -  So, the interesting thing about these holes is that they were actually there when the scribe first wrote the manuscripts. There were defects in the parchment itself during the manufacturing process. So, these were probably tiny, tiny holes to begin with when the skin was fresh and unstretched. But as they stretched them during the parchment making process, the holes expanded. Sometimes you'll see areas where the parchment has been stitched up prior to stretching, in an attempt to avoid that.

So anyway, with the folds, what I do is I take a piece of agar and then I put it on top of the fold like so. Just in the area where the fold is, so itís very targeted and very precise. And then I let it sit there and wait, usually, itís weighed down just on the sides to make sure that it has even contact with the surface of the parchment. Once it has reached the level of optimum humidification, it just gets folded back over, pressed flat with silicon release paper to prevent sticking and then some blotter to help wick away the moisture.

Matt - Itís kind of like a fancy way of steam ironing. Like I used to do this with my homework if it got too folded up, you can just whack it up under the steam iron and then the moisture and the steam would help to flatten it out.

Lucy - Yeah, itís like that without the heat and itís less aggressive as a form of conveying moisture.

Matt - Gentle ironing.

Lucy - Yeah, very gentle.

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