This blog post is part of a series of observations about the London “Gels in Conservation” conference co-hosted by the Tate and IAP (International Academic Projects, Ltd). In mid-October, over the course of three days, some 41 authors presented research, techniques and ideas on gels in conservation. The talks were excellent, and I’ve focused on four that were notable for the wide range of materials treated and challenges faced. They ranged from coating/grime removal from a giant sequoia tree cross section, to dirt and varnish removal from Delacroix wall paintings, to removal of repairs from a fragile felt hat from a 18th century ship wreck, and an experiment comparing residues left behind by various gels on paper.
In the second of four talks, Alina Moskalik-Detalle presented “Conservation of murals by Eugene Delacroix at Saint Sulpice, Paris.” The talk was interesting for its scale and challenges. Because I’ve gone to see these murals many times over the years, the talk was also personally interesting. Each time I visited, I left somewhat disappointed by the darkened, flat, dull murals. As luck would have it, I was scheduled to travel to Paris a week after attending the gels conference. What I saw when I visited Ste. Sulpice was truly remarkable—color, depth, and drama. The cleaning had totally transformed these murals. Naturally, I couldn’t help myself, I actively looked for shiny patches—the results from this treatment were remarkable. This multi-year project involved numerous conservators including collaboration with Richard Wolbers. Some of the treatment challenges included flaking paint, complex paint layers, multiple restorations, rising damp in the walls, carbon based grime, and, if that wasn’t enough, the paint was very sensitive to organic solvents. The conservators wanted to limit penetration of their solvent gels without leaving a residue or tide line behind. They wanted good contact between the gels and the substrate, control of the action of water, and to create mixtures of solvents that would clean effectively without damaging the paint layers. After cleaning tests were performed, a treatment protocol emerged: by pre-saturation of the areas being treated with cyclomethicone followed by the application of silicone solvents gels to the mural’s surfaces, tide lines were avoided, grime could be removed, the gels could be cleared, and residue was limited. The D4 was a slow evaporator which allowed about a 30 minute working time for the application of the gel and subsequent grime removal without harming the paint layer.
The gels were made and applied in a paste-like consistency for maximum control of where the material was placed. It clung to the vertical walls and horizontal ceiling long enough to be effective. Using D4 based emulsions to clean the mural’s paint surfaces allowed the removal of surface soil without stripping wax or oily components from the paint films themselves. Because the emulsions were surfactant free, it was easier to clear them from the treated surfaces. Analysis of samples didn’t show residue left behind on the surface, but when the conservators tried to consolidate flaking areas of paint, they had trouble with adhesion, it is unclear why. It will be interesting to see how these murals age over time and if further treatment is needed in future, how re-treatable it is.
This blog series is a result of receiving the FAIC Carolyn Horton grant to help me attend the conference. I would like to gratefully acknowledge the FAIC for helping make it possible for me to attend this important conference.