Head to toes: the treatment undergoes

In Part 2 of this special AM blog series, Melissa Holt tells us about the treatment process for two of the Egyptian cartonnage objects which includes x-ray analysis and tear repairs!

Welcome to the second blog of this 4-part series, where I take you through the treatment process of four cartonnage objects. In the last AM blog, I explained what cartonnage is and discussed what the goals and plans are for the conservation treatment.

Since the then, lockdown in Sydney has ended, which means the treatment for these fascinating objects can finally begin. In this part I will detail some of the steps during a conservation treatment and discuss some of the hurdles that we have faced so far.

Step 1: Investigations

Before treating an object, we need to learn as much as possible about the object. One way we’re attempting to gain more in-depth knowledge about the objects is through radiocarbon dating. We sent samples of the cartonnage off for testing which will provide us a more accurate age of the object. We were able to get clean samples from three cartonnage objects (E019000, E021583-006 and E021583-006), but this wasn’t the case for one of the cartonnage masks (E019001), due to the extent of modern repairs. We are currently waiting with bated breath to find out the results. We also decided to X-ray the objects, in the hopes of capturing an anomaly with the cartonnage – and we have had some success on this front. The X-ray of E019001 shows a large dark area at the top of the head which suggests that there is no linen in this area. That means that the entire area on the forehead is reinforced from the modern repairs, which are more extensive than we originally thought. We also performed FTIR on E019001. FTIR (Fourier-transform infrared spectroscopy) utilises infrared light to detect different molecules within a sample and produce a spectrum. This spectrum is then compared with spectra of known materials to identify what it is. From this we learnt that the glue that was used in the past is an animal based glue and the paper repairs are cotton based.

Step 2: Observing the difficulties

The next step is to acknowledge what is going to be difficult to treat and how to tackle it. As mentioned in the previous blog, E019001 has extensive historic repair. It is likely that these repairs were completed before the object entered the collection in 1910 because we have no records or images of the mask looking any different than what it does today. If we are correct, this means that these repairs are over 100 years old, and therefore have become part of the history of the object. Due to the age and working properties of animal based glue, treating the historic repairs has proved difficult as you will see below.

Step 3: Getting into shape

Before you can start fixing tears or cracking in an object, you need to make sure all the pieces of the puzzle line up. To do this, we need to slowly reshape the object using local humidification. Blotting paper is dampened with distilled water which is then placed between a layer of spun polyester and thin acrylic sheeting, and then placed in the area you wish to humidify. The polyester acts as a barrier between the object and the water and the thin acrylic keeps the blotter from drying out. By weighting this ‘sandwich’ down, I was able to flatten the modern paper on E019001. However, within hours of removing the weights, the paper had curled back up again. The animal glue tends to shrink as it ages, which caused the paper to curl up. Unfortunately, although the glue will soften and allow the paper to relax, the memory in the bonds of the glue means that when it dries, it curls up again. (We had a discussion about removing the paper, but we believe this will be too damaging and could lead to the loss of original material).

Reshaping E021583-006 however was much easier. Pegs and weights were used to hold the humidification sandwiches in place and allowed me successfully to realign all the fragments.

Step 4: Stay where you are

During the humidification of E019001, I saw that areas of the linen and modern materials were softening which could lead to the loss of material. To prevent this, it was decided to consolidate the inner surface. I used both 1% and 4% methylcellulose in water. In the video below, you can see that I alternate between brushes. Before applying my adhesive, I was applying a small amount of ethanol. The ethanol helps to pull the adhesive in to the object and when it evaporates it helps to bond the adhesive to the object with greater strength.

Step 5: It’s time to come together

After reshaping, it was time to begin repairing the front edge of E021583-006.There were several tears and loose fragments along the front edge. To repair this, Japanese tissue paper was used as a backing layer on the inside of the covering to add strength to the splits. Japanese tissue paper is an archival material commonly used in paper conservation to repair splits and tears. In the video below, you can see that I apply the adhesive both to the paper and to the linen before sticking them together. Once in place, spun polyester and a piece of dry blotter is weighted in place. This was to draw out excess moisture and ensure strong contact with the object. These repairs brought all the loose fragments together and added great strength to the originally weak front edge.

Please join me for part 3 in this blog series, where we will begin to work on the front painted surfaces of the objects!

Melissa Holt, Project Conservator, Collection Care and Conservation, Australian Museum.