Last summer, we were joined by a Conservation Trainee, Helen. Today, she has written us a follow-up post…
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Four months later…
It has now been four months since I was last in the conservation lab at the DHC, and I can’t believe how quickly the time has flown! I gained an immense amount of experience and confidence during my placement, and I am excited to share how this has been instrumental in my studies so far this year. In particular I have had a lot of experience with gelatine dry plate negatives, which are a type of glass plate negative.
Cleaning Glass Plate Negatives
Glass plate negatives (GPNs) are a type of photographic material commonly found in archive and museum collections. It is from these negatives that positive prints can be made, their preservation is therefore super important as without the negative no more prints can be made, and the image may be lost forever! The glass plates I have worked on at the history centre and during my course consist of a layer of glass (called the support), coated in a gelatin and silver emulsion. The gelatin is really sensitive to moisture, so it’s very important that when cleaning, the emulsion side isn’t exposed to any unnecessary moisture. I got a lot of practice with cleaning these over the summer when cleaning the Hardy plates acquired by the DHC, which I detailed in one of my previous blogs. I cleaned the glass side of these negatives with a slightly damp cotton bud, being careful not to get moisture over the edge of the plate, and only cleaned the emulsion with a soft, dry brush.
As part of my practical projects at Cardiff University, I was given a set of glass plate negatives from Brecknock Museum’s local collection in y Gaer. These had become stuck together due to a film negative sandwiched between them. Cellulose nitrate has been used since the 1880s as an alternative support material to glass for negatives. Unfortunately it is very unstable, highly flammable, and prone to exploding! As it ages the film gets sticky and brown and in this case the film has degraded while sandwiched between glass plate negatives, sticking them together.
I was able to pry them apart without any breakages, but there was a lot of sticky, brown gunk left on the glass of some of the plates which needed cleaning. From my experience at DHC I knew water was safe for cleaning the glass, but unfortunately this wouldn’t remove the gunk! I knew from conversations with Jenny about cleaning, that alcohol could also be used, if necessary, but I had to look into what cellulose nitrate was dissolvable in and then research whether this was suitable for these plates. In the end I settled on acetone, as it dissolves cellulose nitrate, doesn’t degrade the glass and evaporates quickly. It was thanks to my experience with the Hardy plates and Jenny’s knowledge that I had an idea of what to look for and the sort of criteria it needed to fill.
Organising and rehousing
While at the History Centre, I was also tasked with organising and rehousing a large number of new acquisitions of glass plate negatives from around the south-west. I had to try and figure out where each plate was from and organise them into counties so that we could separate the Dorset ones from the non-Dorset ones. To do this I had to again clean some plates that were particularly dirty and research how to safely rehouse this type of glass-based photographic material. This research has already come in very useful during my course as I have to rehouse my now-separated group of glass plates, and I have also been given the responsibility of rehousing the entire collection of photographic materials from the Brecknock Museum at y Gaer! From my research and experience at the DHC I know what materials can be put in what housing (e.g. glass should be wrapped in paper), how to store glass plate negatives without putting them under too much stress, and to make sure there is spacing in boxes to stop them getting too heavy.
Final thoughts…
I cannot thank Jenny enough for all the knowledge and experience she shared with me over the summer. There are so many ways that my time at the History Centre was helpful in building my confidence as a conservator. I’ve used so many techniques and procedures that I learnt at the DHC for photographic materials, and I can’t wait to put my book and paper knowledge into practice with future practical projects over the course of my studies.
Finally, it would be really useful if, having read this blog, you would take just a couple of minutes to complete a short survey please! The survey is completely anonymous and your feedback will help provide data to be used in my academic studies. Thank-you!
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If you’re interested in reading more about what a conservation placement entails you can read my previous blogs here:
Conservation Tales: A Conservation Trainee
Conservation Tales: Glass plates of Thomas Hardy
Thoughts of a Conservation Trainee
And if you’re interested you can find more information about Brecknock Museum and y Gaer at the links below: