In 2015 London Stone Conservation completed the cleaning and conservation of the alabaster sgrafitto roundels at St Stephens Church in Hampstead. The works further restored the interior of the early French Gothic building to its former condition, following years of neglect and a long period of dereliction.

Sgafffito is an ancient technique where the surface of the alabaster is scratched or chiselled, before being filled with a tinted contrasting plaster. The surface and filler are then finely polished to create decorative schemes and patterns. The name comes from the Italian, and literally means ‘scratched’.

The 10 roundels at St Stephens depict Saints and religious figures and are situated on each of the spandrels throughout the nave. The alabaster disc is contained within a Bath stone frame, with gilt and polychrome decoration. The roundels had deteriorated significantly over the years, due to exposure to moisture from a leaking roof and broken windows as well as a build-up of atmospheric soiling. Over the years, insensitive cleaning methods had further damaged the painted and gilt surfaces, causing discolouration, abrasion and loss. Many of the roundels had also become loose within the stone and brick framework.

The alabaster surfaces were carefully cleaned using a non-aqueous agent and soft sponges. The Bath stone surround was cleaned using non-ionic detergent to emulsify and remove the heavy build up of dirt and moisture staining. Following analysis of the historic paint layers and site samples, a match was prepared for the original colour and characteristics of the red oxide border. The borders were repainted by hand to the original lines and arrangement and the quatrefoil patterns oil gilt using gold leaf. To further protect the alabaster discs, two layers of microcrystalline wax were applied to the surface.