Stone Carvers • Stone Masons • Stone Conservators

sketch of boss for westminster abbey

Westminster Abbey Plaster Boss 2001

Repair to plaster ceiling boss

The plaster casts of art schools, often dating back to the nineteenth century, were once considered an essential means of training by the intensive study of form: they were the subject of formal still life; their underlying geometry was explored; they were copied in clay maquettes; they were then carved in stone.

In the 1960’s, the large majority of the plaster casts were lost to a wave of ideological iconoclasm. They were broken, thrown away, sometimes hidden. Since then, their value as aids to study has reasserted itself. What few that remain require careful conservation.

This particular cast had suffered damage and loss over the years; attention was due.
Little was known of its background.


Affectionately called ‘The Helicopter’, much of its top tier of foliage had disappeared.
After considerable research under the direction of the late John Roberts (sculptor), it was identified as a copy of one of a series of bosses in the Chapter House vestibule of Westminster Abbey. These bosses were exceptionally fine Victorian reproductions of the Gothic style by Gilbert Scott’s carvers in the 1860’s. Each boss slightly varies, according to the individual carver’s temperament, as would have been the case with the replaced Gothic originals. Photographs of the stone bosses in the vestibule were taken, although close access for measurements was denied for Health and Safety reasons.

John Roberts suspected that ‘The Helicopter’ was a plaster cast of a clay mould, as there are traces of clay texture on its base, and the top of the rib vaulting is flattened out, as can be seen in the geometrical studies. This theory, however, could not take account of the complex casting and fine plasterwork of the ‘rotary blades’ of the top section, particularly as there was no evidence of a later plaster-to-plaster join between the rib-vaulted base and the florid upper sections of ornament.
A careful study of the geometry of the piece was conducted by a series of scale drawings. It was discovered that the piece expressed the golden section in a three-dimensional plane throughout the proportions of its elements. This would further explain the overall harmony across the various renditions of Gothic style bosses that Gilbert Scott’s carvers achieved in their day.

Looser drawings were also made, in order to focus an appreciation of the movement of the forms, gain a feeling for the work.

Under close supervision of the Conservation Department at City & Guilds of London Art School, it was decided to replace the lost fragments and a method was subsequently agreed upon.

The method required the principle of reversibility, so that the new replacements could be removed if required, without causing harm to the original cast.

Therefore, the broken sections of the original cast were sealed (reversibly) before commencing clay modeling, in order that the clay would not create damage by damp or staining.
The new sections were modeled in situ in clay, then removed once hardened out, and cast into plaster using Alginate (a waste mould method).

Once re-worked with rifflers and files, the new sections were attached to the original cast using a paraloid adhesive (reversible).

The results have favourably endured.



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Stone Carvers • Stone Masons • Stone Conservators

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