I recently attended a one-day workshop at the RCAHMS conservation studio regarding the preservation and conservation of glass plate negatives. The day was split roughly into two parts, with the first half of the day dedicated to lectures in digitising glass plate negative collections, preservation, identification of damage and the conservation and stabilisation techniques available for broken negatives. Practical sessions were conducted by ICON intern, Marta Garcia-Celma during the second part of the day when the group were given a practical demonstration of the cleaning procedures of glass plate negatives, gelatine consolidation, and a stabilisation technique for cracked and broken negatives called the sink mount with pressure binding technique. This system of encapsulation uses blotter to create a tight fitting frame-mount and two pieces of clean glass to sandwich the broken glass plate negative within, allowing the plate to be safely handled, digitised and stored. I shall discuss how to make this enclosure in more detail during this blog post as I had never undertaken such a procedure before, finding the experience insightful, rewarding, and very fiddly! First of all though, chaps, you need to find yourself a broken glass plate negative. Here’s one I prepared earlier! Cue Blue Peter theme tune…
Once you have completed surface cleaning the glass side of the pieces of broken plate using a very soft squirrel hair brush and dampened cotton wool, you may begin to create your flush repair. You start by wiping the surface of two new pieces of glass with IMS (industrial methylated spirit), which should be cut slightly larger than your glass plate negative. Next, you should place your broken glass plate negative emulsion side down onto a piece of blotter (about 1cm larger than your plate and the same size as your new pieces of glass) and splint the broken pieces back together using filmoplast p90 tape. This is a delicate and time consuming process, however the key thing to remember is to avoid sticking the splints down too much, otherwise you’ll have a real job of pulling them off again later!
To create a tight fit within the blotter sink mount, you should carefully score around the edge of the negative using a scalpel blade then cut out the centre of the blotter and discard – you only need the outer rim to act as a frame-mount for your glass plate negative. Your glass plate negative should now fit snugly in the newly cut centre of the blotter. This part of the process is probably the trickiest, as it is very important for the mount to fit tightly and perfectly around the glass to avoid movement – a saggy mount will not do! Then once you have placed your newly mounted glass plate negative on to your clean sheet of glass and removed your splints you can begin the procedure of binding your glass sandwich together!
With your broken glass plate negative snugly within its blotter mount and now sandwiched between two new sheets of glass you can bind the edges together using a pasted out strip of silver safe photographic paper; roll your glass plate along the pasted paper and secure as you go. This part is also fiddly mainly because the pasted out strip is damp and weak. So don’t be namby-pamby about it, you don’t want to lose grip of your sandwich whilst smoothing down the binding paper! Once the whole glass sandwich is bound you can snip and fold the corners to make them neat and pretty.
And voilà! Your broken glass plate negative is now easy to handle and store, which is quite jolly considering its prior sorry shattered state and always worth a shot if you ask me….
Post by Samantha Cawson, Conservation Intern
Terrific post. This certainly makes our job of capturing a good quality image a lot less fraught. Plus less intervention work needed from us to deliver a presentable image.