The front part of the lamp was extremely friable, and a large area of the surface had been lost. Delamination was occurring in the interior of the lamp too, and a collection of fragments has built up inside.
To determine how to consolidate the delaminating clay, loose fragments retrieved from the interior of the lamp were used as test material.
We tested varying percentages of Paraloid B72 (ethyl methacrylate co-polymer) in acetone (organic solvent ketone class).
None of the lower-percentage solutions seemed to adhere the larger flakes to the substrate, so it was decided to use a 5% solution to achieve this. The consolidant solution was inserted beneath the flakes using a hypodermic needle. Any overspill was removed immediately with a small swab dampened with acetone.
When the exterior of the lamp had been satisfactorily consolidated, attention was paid to the interior of the lamp. Any remaining loose fragments were removed and then the interior consolidated primarily with a 1% solution; once the solvent had evaporated, the process was repeated with a 2% solution.