Same, same but different
Our first proper workday consisted of continuing the consolidation of the paint surfaces of the side wings and the backdrop.
In projects like these, the choice of materials and methods is determined by doing tests and discussing the results. Similar problems might need different solutions.
The backdrop group focused on continuing the consolidation of the powdery paint layer. The stress of the canvas closest to the beam has been most severe, due to rolling of the canvas when lowering and lifting it. Abrasion from the repeated movement has caused the loss of cohesion in the paint layer. The aim is to secure the powdery paint by adhering it to the support with a consolidant.
In conservation it is preferred to introduce as little consolidant (or other new materials) as possible. The size and weight of the object, the flexibility of the canvas and the fact that it is hanging from a beam and might be rolled up and down from time to time, were also factors that needed to be taken into account when choosing the consolidation medium. It was decided to use sturgeon glue applied by airbrush. In this way only a minimum amount of consolidant is introduced and the canvas keeps its flexibility. In addition the mist causes minimum pressure on the paint layer. It is important to practice the technique beforehand, to achieve an even distribution. It is therefore very helpful to try out the airbrush pen filled with coloured water on a sheet of paper first.
For the side wings the choice of consolidant is Methocel A4C applied with brush through Japanese tissue. This method ensures better penetration, and therefore binds the pigment particles better to the canvas, than the airbrush method, but it stiffens the canvas slightly. The side wings consist of canvas mounted on a wooden frame, and do not need to be rolled. Therefore, it can be used in this case.
Cellulose ethers are an established material and used in conservation for about 35 years. Methocel A4C is a rather flexible material and in a dispersion with ethanol, it has good wetting properties. It can also be used as an adhesive, for cleaning and as a bulking media.
Both consolidants were chosen because they are stable and have excellent ageing properties. Two characteristics that are especially appreciated in conservation! Even though we have similar problems, we sometimes need different methods and materials for the various conditions of the objects.