The Conservation of a Pottery Vessel (EC1376)

This blog post is written by Katie Morton, a second year Conservation Practice Masters student at Cardiff University. Katie previously completed her undergraduate in Egyptology at Swansea University. Her main interests are pottery and ceramics, but she is starting to get hands-on with other materials, such as plaster (HARGM10873).

My first encounter with EC1376 was when I was an Egyptology student at Swansea University, completing research for my dissertation into the blue painted pottery held at the Egypt Centre. EC1376 was in a box with one of my study objects. Although it was not included in my dissertation, Dr Ken Griffin and I checked to see if most of the vessel was there, then made a note to have it conserved at Cardiff. Fast forward to the summer of 2024 and Ken came across the vessel again and asked if I wanted to conserve it over the summer holidays. Of course, I accepted!

Fig. 1: Sherds of EC1376

When the vessel first came to Cardiff it was in multiple pieces, with some sherds already stuck together and almost all of them covered in an adhesive from a previous reassembly (fig. 1). When the vessel was dropped off at Cardiff, Ken mentioned the adhesive was most likely animal glue, which was commonly used in the past for sticking together objects in museums and during early excavations in Egypt. One of the properties of animal glue is that it is soluble in warm water, which means that, in theory, it should come off when brushed/soaked in warm water (fig. 2). Due to the amount of adhesive that was present on the sherds, the decision was made to give them a bath overnight. This is where things got complicated!

Fig. 2: Sherds in warm water

 

The next day I came in to find the adhesive had turned grey and hadn’t softened at all (fig. 3). At this point the decision was made to do some investigation as to what the adhesive may be. Prof. Phil Parkes (Cardiff University lecturer) and I did a Fourier Transform Infrared Spectroscopy (FTIR) to look at the chemical composition of the adhesive. Unfortunately, the spectrum was inconclusive, showing aspects of organic as well as synthetic material. Whilst the spectrum did not yield any helpful results, when comparing my sample to those of previous students, there was a match to another vessel from the Egypt Centre. Due to time constraints, there was no time to investigate this further. However, it may make an interesting project in the future.

Fig. 3: Greying adhesive

 

The next step was to try the variety of solvents available in the lab, including acetone, IMS (Industrial Methylated Spirits), toluene, and white spirits, none of which were successful in removing the adhesive. The option of manually trying to remove the adhesive with a sharp tool was considered. However, it was deemed too damaging to the vessel. Finally, Phil suggested we try chloroform as it is a stronger solvent than the others used. Due to chloroform being a volatile liquid with severe side effects from exposure, all work was done in a fume cupboard whilst wearing gloves. We tested it out on one of the smaller sherds and it very quickly became evident that it was softening the adhesive and allowing removal without causing damage to the sherd. We decided to create a chloroform environment, where a small amount of chloroform in a beaker is placed into a sealed Tupperware box with some of the sherds and left overnight. The next morning the adhesive on the sherds was a lot easier to remove. Over the next week, I spent a total of 19 hours carefully removing the adhesive using a hard brush, a sharp tool, and some extra chloroform (fig. 4).

Fig. 4: Removing the adhesive

Once all the sherds were clean and dry, I completed an initial test run of putting the vessel back together to see how much of it was present. This was an important part of the process as some of the sherds ‘floated’ and could not be placed due to the large gaps. After a discussion with Ken, the decision was made not to complete gap fills in the voids as the vessel was structurally stable without them. Knowing all this, the reassembly process began. Due to the porosity of the material of the vessel, a layer of adhesive called Paraloid B72 at 20% was brushed over the joins of the sherds. This creates a barrier, meaning when the main layer of adhesive is applied it does not absorb into the fabric, causing the join to fail. Paraloid B72 was chosen due to its reversibility in acetone, meaning if there are any errors they can be easily rectified. The first few attempts of the initial reassembly failed due to the percentage of the Paraloid not being high enough. Once I made Paraloid B72 at 40% the joins were successful and after 14 hours of reassembly, the vessel was completed, with only one area needing to be redone due to being misaligned (fig. 5).

Fig. 5: EC1376 rim reassembled

What started as a seemingly easy task turned out to be more complicated than we imagined. Despite the issues encountered, the conservation treatment was successful. Over a four-week period, I spent a total of 42 hours working on this vessel, and it is now back at the Egypt Centre. This work means that this vessel can be studied as a complete artefact, being measured accurately, and its shape is now identifiable (fig. 6). It has been really fun working on this vessel and I look forward to working more with the Egypt Centre in the future.

Fig. 6: Completed vessel

Bibliography:

Atria. 2024. What is FTIR. Available at: https://atriainnovation.com/en/blog/what-is-ftir/ [Accessed: 4 November 2024].

Horie, C. V. 2010. Materials for Conservation: Organic Consolidants, Adhesives and Coatings. London: Routledge.

Schellmann, N. C. 2007. Animal glues: a review of their key properties relevant to conservation. Studies in Conservation 52(1), 55–66.

Science Direct. 2024. Adhesives for Packing. Available at: https://www.sciencedirect.com/topics/engineering/animal-glue [Accessed: 4 November 2024]

The Egypt Centre. 2024a. History of the Museum. Available at: https://egypt.swansea.ac.uk/history-of-the-museum/ [Accessed 4 November 2024]

The Egypt Centre. 2024b. EC1376. Available at: https://egyptcentre.abasetcollections.com/Objects/Details/2680?SavedSelections=$Search-EC1376$Page-1 [Accessed: 7 November 2024]

UK Health Security Agency. 2024. Chloroform: General Information. Available at: https://www.gov.uk/government/publications/chloroform-properties-incident-management-and-toxicology/chloroform-general-information [Accessed: 4 November 2024].