Conserving Cartonnage

cartonnage mask detail

The Nicholson Museum’s collection of ancient Egyptian artefacts has many items made from organic and perishable materials such as wood, plant matter, papyrus, linen. Funerary masks made from cartonnage, layers of papyrus or linen stuck and coated with plaster which were then molded to the shape of the body and painted, were commonly found on mummies from the Frist Intermediate period (approximately 2100 BC) through to the late Roman period. The Nicholson’s collection includes several examples of these types of funerary masks, two of which are now on display in the new exhibition Death Magic.

One of these masks, NMR.108, needed extensive conservation work before it was able to be exhibited. A large amount of the plaster material, molded into the facial features on the exterior had been lost and the exposed textiles used to create the interior layers were significantly frayed around the edges, the shape was distorted and had many holes. In addition to its condition, the mask was adhered directly to an old acrylic mount with large patches of shiny adhesive that had been absorbed into the back of the mask.

To prepare the object to go on display our conservator, Alayne Alvis, first needed to remove the mask from the mount. Then the mask needed to be reshaped and given internal structural support.

The old adhesive was removed very gently and slowly by applying small amounts of acetone with a Pasteur pipette. This method enabled Alayne to apply the acetone accurately, and allowed her to regularly check that the acetone was not affecting the front, painted part of the mask.

Having removed as much of the old adhesive as possible, Alayne now needed to provide the mask with support and structure. Following standard conservation practice, the method chosen must be reversible so that in the future any interventions can be removed easily. Alayne adhered mulberry paper to the linen. Mulberry paper, also known as Japanese tissue, is often used in conservation work because it is free of impurities, flexible and has long fibres which give strength. Identifying an adhesive that would connect the paper to the ancient linen required a series of tests. After trying a variety of products at various concentrations the most successful adhesive was a combination of dilute starch paste and carboxymethylcellulose (CMC).

With the mulberry paper adhered, providing a strong internal structure, Alayne was able to start reshaping the mask by placing weights in strategic positions and leaving them in place for a number of days.

The final step was to create a support for the mask. For this process Alayne worked with Kevin Bray, a contracted conservator. After several brain-storming sessions these conservators decided to create plaster and cotton full internal cast, similar to a papier-mâché project. Firstly, a layer of cling wrap was placed over the back of the mask, and strips of cotton were soaked in plaster. Then strips were laid on the cling wrap, overlapping each other to establish a strong cast. The chemical reaction that occurs when plaster is mixed with water is exothermic, meaning that it generates heat. Kevin and Alayne worked slowly to create the plaster support, checking the temperature of the plaster at regular intervals to ensure that the heat from the chemical reaction was not at a level that would damage the object. The end result was a plaster cast that matched the shape of the mask exactly, which provides the rear support of the mask in its display case.

The mask can now be viewed on display in the exhibition Death Magic at the Nicholson Museum.