Plaster cast of an arch by José de Trilles y Badenes about 1971 depicting a fragment from the arch from the interior of Santa Maria la Blanca. The original was sculpted in 1250-1300.

Plaster cast of a fragment of an arch from the interior of Santa Maria Blanca synagogue. The main plaster cast also has ceramic tiles applied at the base of the column.

Cast of an arch from the interior of Santa Maria la Blanca synagogue, made in plaster and with ceramic tiles by José de Trilles y Badenes about 1871 and purchased from Juan F. Riaño in 1871 for £147. The original arch was sculpted by an unknown artist in Toledo, Spain in 1250-1300.

Making plaster copies is a centuries-old tradition that reached the height of its popularity during the 19th century. The V&A's casts are of large-scale architectural and sculptural works as well as small scale, jewelled book covers and ivory plaques, these last known as fictile ivories.

The Museum commissioned casts directly from makers and acquired others in exchange. Oronzio Lelli, of Florence was a key overseas supplier while, in London, Giovanni Franchi and Domenico Brucciani upheld a strong Italian tradition as highly-skilled mould-makers, or formatori.

Some casts are highly accurate depictions of original works, whilst others are more selective, replicating the outer surface of the original work, rather than its whole structure. Like a photograph, they record the moment the cast was taken: alterations, repairs and the wear and tear of age are all reproduced in the copies. The plasters can also be re-worked, so that their appearance differs slightly from the original from which they were taken.

To make a plaster cast, a negative mould has to be taken of the original object. The initial mould could be made from one of several ways. A flexible mould could be made by mixing wax with gutta-percha, a rubbery latex product taken from tropical trees. These two substances formed a mould that had a slightly elastic quality, so that it could easily be removed from the original object. Moulds were also made from gelatine, plaster or clay, and could then be used to create a plaster mould to use for casting.
When mixed with water, plaster can be poured into a prepared mould, allowed to set, and can be removed to produce a finished solid form. The moulds are coated with a separating or paring agent to prevent the newly poured plaster sticking to them. The smooth liquid state and slight expansion while setting allowed the quick drying plaster to infill even the most intricate contours of a mould.
Flatter, smaller objects in low relief usually require only one mould to cast the object. For more complex objects, with a raised surface, the mould would have to be made from a number of sections, known as piece-moulds. These pieces are held together in the so-called mother-mould, in order to create a mould of the whole object. Once the object has been cast from this mother-mould, the piece-moulds can be easily removed one by one, to create a cast of the three-dimensional object.

The walls and pillars of Santa María la Blanca reflect the interplay of three different cultures: Christian, Jewish and Islamic. The church was founded as Toledo’s main synagogue, built by the city’s flourishing Jewish population during the culturally tolerant reign of the Christian king, Alfonso X (1252–84). Although Muslim rule in Toledo had ceased in 1085, many Islamic artistic traditions remained popular. The synagogue demonstrates this with horseshoe arches, widely used in the Islamic architecture of Spain, and new materials, such as plaster, introduced by the Muslim Almohad rulers of southern Spain and North Africa.

Juan Facundo Riaño helped the Museum acquire this cast. A Spanish academic, he was a key figure in the production and collection of plaster casts in 19th century Spain. Riaño was also a close colleague of Henry Cole, the Museum’s first director, and advised him about objects in Spain that might be photographed or cast so that their reproductions would be made available for visitors in London to appreciate.

REPRO.1871:2-60