During my last year of the MSc in objects conservation at University College London, I am fortunate to have been granted a placement in the sculpture conservation studio at the Victoria and Albert Museum (V&A) to fulfil the practical portion of my training. Last September, I became involved in the conservation of the V&A plaster cast collection for a major gallery refurbishment, set to re-open in the autumn of 2018.
Within this project, sculpture conservator Lucy Pieri and I were responsible for the treatment of Repro. 1902-17; a plaster cast of a Romanesque stone carved lintel atop a doorway in Collegiate Church of St. Gertrude in Nivelles, Belgium. The lintel was carved between 1000-1050, and survived the bombing of 1940 thanks to a surrounding wall built in the 17th century. The relief carving depicts scenes from the life of Samson, including, in the centre, Samson slaying the lion, Delilah cutting off Samson’s hair on the left, and the Philistines gouging out Samson’s eye on the right. The plaster cast was purchased by the V&A in September 1901 from the Belgian Commission of International Exchanges along with 57 other plaster casts for the combined total of £52 (V&A records).
An interesting challenge in the treatment of the V&A plaster cast collection lies in the varied coatings present on object surfaces. While trends may sometimes be observed in surface coatings on casts produced by the same workshop, and analyses have been conducted since the start of the gallery refurbishment project, a definitive composition for coatings present on each cast is not always clear. These coatings could represent campaigns during manufacture to seal the plaster for protection against moisture, or pigmenting the surfaces to achieve a certain aesthetic appearance, as well as later interventions. This variety in surfaces ensures that each treatment decision is unique and must be carefully considered. Examination under ultraviolet light can inform this process, sometimes suggesting materials present. The level of saturation of the coating may also be indicated by the visibility of plaster fluorescence, which appears dark purple in the presence of ultraviolet light. The intensity of fluorescence colour may also increase with the aging and deterioration of certain materials.
Examination of this object’s surface under ultraviolet fluorescence suggested the presence of linseed oil and/or beeswax when compared to reference samples. The coating present appears to have saturated the plaster surface to a high degree, resulting in a decreased porosity of the plaster and allowing the surface to remain comparatively robust.
After tests were carried out, a cleaning method was chosen using Tiranti Latex as a poultice applied with a silicone brush. The poultice was used to soften the superficial soiling, which was then mechanically removed using vulcanized natural rubber sponges and cleared with deionized water. This type of cleaning allows for ammonia in the latex to be gradually released during a slightly more prolonged contact time with the surface, softening soiling. This chemical cleaning property is accompanied by the mechanical action caused by the latex’s curing, which occurs during the material’s phase change from liquid to solid, and contains some of the dirt. Superficial and ingrained soiling may be removed by the dual action of this method.
Regarding structure, casts in the collection possess a range of interior systems of support. This cast contains squared iron-alloy bars located at all four edges, resulting in the object’s 106 kg overall weight. In initial examination of this object, a large vertical crack was immediately apparent, visible from both front and back. The treatment also involved stabilisation of the crack by injecting a synthetic polymer consolidant. A shelf was designed which would support the entire length of the object for installation and display, to eliminate an undesirable distribution of weight that might add stress to the object’s structural condition.
Losses surrounding the crack were also filled and tinted using a styrene-acrylate based filler and gouache colours to encourage the object’s overall aesthetic cohesion and legibility of the relief. Exposed areas of the iron-alloy armature, visible from the back of the object, were treated with an iron corrosion inhibitor. This is hoped to prevent their dimensional change through rusting due to interaction with environmental humidity, which could eventually lead to more structural instability, loss of surface, or iron corrosion staining of adjacent plaster.