Week 1- 12th to 16th September – Conservation of Glass Objects with Stephen Koob, Natural History Museum

So to start off my 12 month internship in the conservation of natural history and collections care I went on a week course in glass object conservation. Yes, it was a strange way to start. But I have good reason. The PCU (Palaeontology Conservation Unit at the Natural History Museum) where I am based for the first 3 months is a large and well equipped lab, so is often used to hold courses with practical sessions. As this was my first week, and the course would take up all the lab space and resources I would have been very stunted in my work unless… I went on the course!

So I was a bit unsure at first, I haven’t really worked with glass and it seemed a bit boring – no dead animals, no human tissue but it turned out this is one of the best courses I have been on.  Stephen Koob is a lovely man with a real enthusiasm for glass – hence his work for the Corning Museum of Glass (Corning, New York). There were 11 on the course, including 2 other PCU staff.

Before the course this was the only glass I was interested in

The lectures were limited, the course had a substantial practical element. We learnt about the types of glass and the deterioration of glass – Stephen had lots of excellent examples from his years of work, which was lucky because it was all new to me! We were told about the cleaning of glass – and I am now scared to put any glassware in the dishwasher!

To start off the practical’s we were all given 2 or 3 broken glass objects – some appeared more difficult than others but they all had different problems. We each had one coloured and one clear object.

Coloured glass as given

First task – piece them back together. Starting with my coloured object I thought I had it very easy with only a few pieces, but this was not to be the problematic stage for me. We stuck together what we had with sellotape (everyone had a few pieces missing) – I then used paraloid B-72 on my coloured object as it can be reversed if needed. B-72 will bubble and trap air but this is less visible with coloured glass. I pieced it together quite quickly….

The missing pieces were very frustrating!

… but then came the clear glass object. I stuck it together with small pieces of tape, just doing the bottom section first. We then used an epoxy adhesive (Epotek 301-2) to drip into the fracture lines. The Epotek followed the cracks and filled them until they were near invisible. Epoxy adhesives look much better on clear glass because they don’t trap air like B-72, but they are so strong they can literally pull the glass apart and make it fracture in other places. It’s completely irreversible. It’s also a huge pain to clean up and remove – I would be terrified to us it on anything delicate. Over the first couple of days as I went along trying to piece together the clear vessel until we realised too much of the neck and rim were missing for it to hold its shape, so I could take a mould for the missing pieces… so in the end this object became redundant.

Couldn't go any further with this clear object

However the coloured object was perfect for the job, and threw up an interesting conundrum – how to get the raised pattern of the outer surface. Stephen would usually take a mould from the inside and fill with a resin from the outside – this is easier because of accessibility and having the wider curvature of the object. But Stephen didn’t want any half arsed jobs. So I did it the other way around. I took a mould using silicone of a complete side of the object. I took it from the outside so I got my bumpy raised pattern.

Mold for a fill on a complete side first using silicone

Once dry this would then be fixed to the side with the gap using more silicone. I would then have to mix up a pigment as near to the colouring of the object as possible and add that to the epoxy resin I would be using as a fill. Stephen had loads of tips on what fills, backings and pigments to use to get various finishes one might see on glass.

Filling with epoxy and blue pigment

I did this process for filling twice; the first time the colour was near perfect but the epoxy had escaped slightly from my mould (it is very difficult to get a perfect seal on a textured surface like this); the second was perfect in positioning and texture but the colour was too dark – I had used the same mix of pigment but the pigment has sunk to the bottom in this batch so it was in higher concentration.

First fill

Second Fill

The main problem for me was that the silicone moulds and the acetone used to clean actually lifted off my blue colour which turned out to be just a painted surface (cheap object!), so I ended up with nice blue fills but the object itself being clear in patches!

Stephen also showed us lot of different ways to create fills for rim sections where the mould covered both sides, and for detachable fills made of plaster and stuck in with B-72. Everyone tried different things.

During the week we had a visit to the V&A glass galleries, talks on crizzling and storage, and a trip to the pub – all in all it was a fascinating week and I met some lovely people. But it also helped me get back some of the artistry and dexterity I had lost whilst working in an office – and my sneaky start in the comfort of this group gave me a chance to suss out the museum, department and staff before they could really focus on me. Plus Stephen gave us signed books, our glass objects and any other old equipment to take away if we wanted too!

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