Sculpture conservation shines a light on the plaster casts

We, the Sculpture studio in Conservation department, are really happy to contribute to the project blog and welcome this initiative taken by Melanie, the assistant curator to the project.

For us in the studio the blog is an experiment and offers, we hope, some possibilities for elements of our work on the project to be shared. We hope to put on the blog some of our working processes and images, some of the observations, questions and lines of enquiry along the way, and dialogues in our decision making which might otherwise remain undocumented and private.

Door to Cast Courts

Door to Cast Courts

Most importantly the blog is a chance for us to shine a light on ‘The plaster cast’. What is it materially and technically? What are we looking at? And how do we best prepare these casts for display?

Our perspective is from that of the sculpture conservator and as fortunate persons charged to handle and work with the object.

The project for the sculpture studio is a collaborative one, so far involving 5 permanent staff, one short-term contract staff, 5 students on placements and 2 interns on work experience programmes.

The project currently includes about 700 plaster casts and electrotypes from the collection,of which half were not previously on public display.

Our first practical ‘hands on’ involvement with the project begins with the ‘Initial Assessment’ phase:

Object lists are fixed and given to us. An in-house ‘technical service team’ facilitate making these objects available to us and provide us with a temporary working space in the ‘balcony store’ above the Cast Courts. Lucky us to have such a lofty location high above the courts.

Balcony store

Balcony store

We begin the documentative process for each of the plaster casts from the ‘Object list’: photographs are taken, dimensions and weights recorded and condition assessed. The information, treatment proposals and estimated hours for the works are recorded.

What became immediately apparent during this initial process was the complexity and variety of surface coatings which had been applied to the majority of the plaster casts at some stage in their life.

The surfaces appeared to mimic those of bronze, ivory, stone, wood and gild and rarely retained the appearance of plaster. Unless you read the text panel for material description or intimately know the sculpture this can be misleading.

As we can see: ‘Spot the plaster cast’ from each pair of images:



Closer examination of the edges, top, underside and back of the casts, and areas where the surface has been abraded or chipped the object begins to expose itself. Drip, brush marks and areas of staining can be seen tracing the application of some coating over the surfaces.

What are these surface coatings?

F.F. Frederick (Plaster casts and how they are made, New York: William T. Cornstock, 1899) suggests a list of possible coatings used at the time of making: Linseed oil, shellac, mastic, gum Arabic, milk, casein, metallic powders, animal size among others.

Analytical processes are now underway. Helped by our colleagues in conservation science, and students on placements with us from UCL and City and Guilds of London Art School, we are exploring these coatings further.

We hope to follow through these questions as the project of refurbishment to the cast courts progresses and our attention and focus moves from the smaller portable casts to the larger free standing sculpture in the Gallery and onto the immense architectural casts.

Watch this space.

[The answers are 1A, 2B]