Olduvai Gorge Conservation Project

Anna Funke

This is a slightly different blog post from what we usually talk about. It is supposed to introduce you to a fascinating project that Abby, Jan and I (all MSc Conservation students who you have heard from in the past in previous blog posts) will be involved with this summer. Although our degree has archaeology in the title, you may have noticed that these posts very rarely talk about the adventurous excavations of lost civilisations in foreign lands.

Well that is about to change! The three of us, also known as the GTCT (Greatest Tanzania Conservation Team) will be going to Olduvai Gorge in – you guessed it – Tanzania this summer! We will be in pursuit of some hard-fast evidence about the lives of early man and woman. This famous site is right at the heart of the theory that humanity’s origins are to be found in East Africa.

Olduvai gorge map

The archaeological research at Olduvai focuses on the transition between the Oldowan and the Acheulean. Both these groups are steps in the line of the human biological as well as technical evolution. The archaeologists on site will therefore be looking both for human remains that can give some insight into the biological stages of our development, as well as for ancient stone tools that can shed some light on our early technical developments. The finds from Olduvai Gorge go back as far as 1.7 million years!

Our contribution to these grand questions will be to try to stabilise these fragile finds so that they can safely be studied. We will also try our hands at excavation by helping out with the lifting of particularly fragile finds.

A Tanzanian student in the Laetoli Lab working on a horn core. Photo courtesy of OGAP.

A Tanzanian student in the Laetoli Lab working on a horn core during last year’s excavation. Hopefully, this will be us soon! Photo courtesy of OGAP.

We are now in the final weeks of preparations before the departure of GTCT in early July! We are getting our vaccinations and gathering our tents, travel showers, and tool kits. We can’t wait to jump in and we hope you will stay tuned for updates during the excavation! If you would like us to send you a postcard, we will happily do so in return for a small contribution to our travel fund. We are so close to going but we still need to raise the last of our balance to make this trip a success! You can help by contributing here or by spreading the word about our project. Thank you for any help you can give!

Find out more about the conservation at Olduvai Gorge here.

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A Heavenly Transformation – The Treatment Continues…

Jan Cutajar

Check out the previous posts in the series here, here, and here!

Our last blog post on the treatment of the Norfolk Museums Services angels dealt with some very satisfying flake relaying on Angel A. In this new episode, we shall delve into the treatment of Angel B (shown below in case your memory needs jogging), which had suffered a more severe case of surface delamination than its counterpart. Indeed, the delamination had reached such a severe state that even slights movements of the angel within its packaging resulted in notable loss of gilding!

Angel B, more affectionately known as Gabrielle. Courtesy of Norfolk Museums Service, T1878333.

Angel B, more affectionately known as Gabrielle. Courtesy of Norfolk Museums Service, T1878333.

For this reason, an intensive rescue operation took place earlier this year over three, wintery January days, with the aim of stabilizing the angel so that it may be removed from its packaging and be treated in a similar manner as Angel A. An enthusiastic team comprising of the author, Letty Steer and Dae-Young Yoo was put together and led by a motivating Claire D’Izarny-Gargas.

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The team members hard at work – above, from left to right, Dae-Young Yoo, Letty Steer & Claire D’Izarny-Gargas; below, from left to right, Jan Cutajar, Dae-Young & Letty.

The team members hard at work – above, from left to right, Dae-Young Yoo, Letty Steer & Claire D’Izarny-Gargas; below, from left to right, Jan Cutajar, Dae-Young & Letty.

Given the condition of the angel, it was slightly (if not very!) daunting to actually even consider touching the angel. The first step, therefore, was to develop a method of stabilising very loose flakes. After several initial trials, it was found that the best method, given the time frame we had to work in, was to apply a Japanese tissue paper facing (adhered directly with a 2% w/v solution of Klucel G in isopropanol, a hydroxypropyl cellulose adhesive commonly used with organic materials), which was then heat-activated using the heated spatula. This step allowed the gilding flakes to be slightly re-shaped in the process before relaying. You can see these facings in the pictures above – here are some more detailed shots of the procedure.

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Applying the Japanese tissue facing using 2% w/v Klucel G – where possible, the areas of flaking were cleaned first, as can be seen. Sometimes though, this was not possible and facing was applied directly to severely flaking sections.

Applying the Japanese tissue facing using 2% w/v Klucel G – where possible, the areas of flaking were cleaned first, as can be seen. Sometimes though, this was not possible and facing was applied directly to severely flaking sections.

The same procedure used to relay flakes on Angel A was then used, applying solutions and heating through the paper facing, which was possible due its fibre-thin nature. Once the gelatin (5% w/v in deionised water) had set hard after 5–10 minutes from heat-activation, the facing was removed by first moistening it with lukewarm deionised water and then peeling it off at a 180o angle with a pair of pointed tweezers. Any clean-up of excess gelatin or paper threads could then take place with warm water swabs.

Here’s an example of the complete treatment procedure: (1) flakes before treatment; (2) facing applied; (3) application of 50% IMS and gelatin, followed by heat activation; (4) after setting, the facing is removed with a warm, wet swab; (5) tweezers are used to pull the facing gently off; (6) the area after treatment, success!

Here’s an example of the complete treatment procedure: (1) flakes before treatment; (2) facing applied; (3) application of 50% IMS and gelatin, followed by heat activation; (4) after setting, the facing is removed with a warm, wet swab; (5) tweezers are used to pull the facing gently off; (6) the area after treatment, success!

Once we were confident that this method worked, the angel in its packaging was set on the operating table and the areas identified as most fragile were faced and treated. There definitely was a ‘surgical theatre feel’ to all this, with two conservators each working on each side of the box, passing around spatulae, brushes and adhesive solutions. Everyone fell promptly into their roles and the rhythm of work got going.

Here, Claire and Dae-Young are stabilising the angel, before its removal from its temporary packaging.

Here, Claire and Dae-Young are stabilising the angel, before its removal from its temporary packaging.

The “operating table” so to speak, with different parts of the treatment taking place at the same time.

The “operating table” so to speak, with different parts of the treatment taking place at the same time.

Letty and Young heat activating the Klucel G and gelatin using heated spatulae.

Letty and Young heat activating the Klucel G and gelatin using heated spatulae.

After the first day, the angel was lifted out of its box successfully without any severe loss of gilding. This allowed us to access more surface area on the angel and so the work intensified during the next two consecutive days, as you have seen already in some of the photos. Facings were applied, flakes were relayed and facings taken off. The most challenging areas were the face, wings, chest and feet on the angel due to the undulating surfaces and level of decorative carving. At times, some flakes were broken or damaged during treatment which was heart-wrenching, however, the solution to this was very straightforward: document it and then repair it.

Some stunning work achieved by Claire on the face of the angel.

Some stunning work achieved by Claire on the face of the angel.

Similar successes on the left wing – clearing the facing was particularly tricky here, as it tended to catch on the decorative carvings, lots of care and caution were thus necessary to achieve these results!

Similar successes on the left wing – clearing the facing was particularly tricky here, as it tended to catch on the decorative carvings, lots of care and caution were thus necessary to achieve these results!

At the expiry of the available time, the angel was miraculously looking in much better shape than before, and in turn was also much more stable! Indeed, the success of the treatment allowed us to move the angle from a lying, horizontal position to a standing, vertical one. Advantageously, this then permitted an improved packaging solution to be implemented whilst more work was carried out at a later stage.

The angel after three days solid work – and finally standing whole!

The angel after three days solid work – and finally standing whole!

Yes, despite the advances made at this stage, the treatment was not yet over and further relaying of gilding and paint was necessary. This was completed in part during another similar session in February. In fact, should you wish to know about this session, we will be more than happy to answer your questions in person at this World Archaeology Day Festival at the UCL Institute of Archaeology, come Saturday the 13th June! There’s an even more exciting part though! We shall be working on the angels this Saturday and you will have the opportunity to see how this work is done in real-time. So don’t miss out on this fantastic opportunity to set your eyes on these angelic beauties, we look forward to seeing you!

WE LOOK FORWARD TO SEEING YOU THIS SATURDAY!

WE LOOK FORWARD TO SEEING YOU THIS SATURDAY!

N.B. All photos by Claire D’Izarny-Gargas & Jan Dariusz Cutajar. Permission to post courtesy of the Norfolk Museums Service.

Material Spotlight: Agar Gel

Robert Price

I’m just going to come out and say it – gels are pretty amazing.

Jurassic Park (1993)

Jurassic Park (1993)

No, not this kind…

I mean, sure, Jell-O or Jelly is pretty great too, but I’m talking about the gels used in conservation and my new favorite gel – Agar.

If you’ve done some lab work you’ve probably come across Laponite RD (a synthetic clay), Carbopol (a carbomer resin), or Cellulose Ethers like Methyl Cellulose or Sodium Carboxymethyl Cellulose being converted to gels for cleaning techniques involving water, solvents, or other cleaning agents.

Gels are useful because they minimize the total amount of solvent or water needed for a treatment by slowing the rate of evaporation and maintaining good contact with the surfaces targeted for cleaning – this is good for you, the environment and the object. In some circumstances gels can also have a poulticing effect and are capable of absorbing a portion of the materials they solubilize or soften.

Aside from potential chemical interactions, a big consideration with gels is how easily you can remove them once they have worked their magic – a process known as ‘clearance’. With some gels this might be particularly problematic, especially when used on very rough or porous surfaces. Not all gels are the same though and you need to do some research.

But here’s where my new favorite material comes in – enter, Agar gel.

If you look into the literature you might be surprised to see the wide range of materials it has been used to clean, including: wax sculptures, marble, gypsum plaster, ceramics, wood, and textiles. Anecdotal reports from our peers currently undertaking work placements have also noted its growing use within museums, especially for surface cleaning on limestone.

The beauty of the gel is that it’s capable of slowly releasing water in very small amounts, which means that it can be used to remove or soften water-soluble materials without overly saturating a water sensitive surface. Unlike other commonly used gels, the rigid gel formed by Agar is extremely easy to remove in a single piece and leaves no visible residues behind. This minimizes the amount of mechanical action needed to clear the gel. You should be aware, however, that at least one study has identified trace amounts of polysaccharides within cleaned materials analyzed with GC-MS.

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Comparative clearance tests with commonly used gel concentrations on Melinex

Personally, I have found it to be a promising material for softening and removing proteinaceous glues in situations where excessive amounts of water or heat would be problematic for the object being treated – as is the case for bone and wood.

It’s definitely worth experimenting with, even if you don’t currently have a use for it. While purified agarose can be purchased online, food grade Agar is much cheaper and can be purchased from higher end grocery stores. Even some high profile cleaning projects have gone with this cheaper alternative. I’ve been using Clearspring® Agar Flakes.

Try making a 2% w/v gel by adding 2g of agar flakes to 100ml of boiling water and a allowing the solution to cool within a flat container. The resulting sheet can be cut into whatever shapes you need and will keep in the fridge for a week or more depending on the cleanliness of your equipment and how often you open the container.

A square of Agar gel, roughly 3mm thick.

A square of Agar gel, roughly 3mm thick.

Unfortunately, these tidy little sheets only work well on flat surfaces. As an alternative, the semi-cooled solution can also be placed in a plastic syringe and extruded just before gelation occurs, allowing the gel to better conform to complex surfaces. This takes some practice and familiarity with the material but can be very effective.

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Direct application of the gel near its ‘sol-gel’ transition temperature.

Finally, you can also experiment with forming the gel around other materials as I did with natural fiber strings. The string can be repeatedly dipped in and out of the warm solution until a thick coating is formed around the fibers. Strings with looser twists and greater surface area work best. This gives the gel a support structure and made handling and removal even easier. Possible applications could be for disassembling narrow joins or lying over curvilinear shapes.

Non-dyed, natural fiber strings used as ‘scaffolding’ for the gel

Non-dyed, natural fiber strings used as ‘scaffolding’ for the gel

Hopefully this has been helpful and got you excited about exploring Agar gel further. It might be a good alternative to consider the next time you have to remove proteinaceous glue from a fragile or water sensitive surface.