The sculpture of St Catherine of Alexandria came to the workshop after it had suffered impact damage resulting in several losses and fractures to the structure. In addition, the gilded surface was in a poor state, much of the gold leaf had been lost and a cracked and poorly applied priming layer was obscuring the carved surface. Samples of the surface were taken and examined under the microscope, revealing multiple layers of oil gilding beneath the present scheme.
It was decided that in addition to structural repairs, the present degraded decorative layer should be removed and a full re-gild be undertaken.
Following consolidation and reintegration of broken pieces, losses were modelled up in gesso putty. The cracked degraded layer was carefully mechanically removed, and the surface was prepared with an oil priming layer matched in colour to the earliest such layer seen in the microscopic analysis.
The sculpture was then re-gilded. It was decided to match the finish of the sculpture to her original splendour when first placed on the ceremonial barge for which she was made in 1656.