The weekend just gone was Heritage Open Weekend (Journées du patrimoine) and as part of it the Chapelle de tous les saints in Preuilly was open to visitors. On the Saturday the two wall paintings conservators gave presentations inside the chapel to tell people about their work there. Sabine de Freitas did the morning presentation, talking primarily about the iconography of the decoration, including the painted oak vault that has been conserved and the danse macabre on the interior walls that we have yet to raise the funds to conserve.
Corinne presenting the conservation work to the public.
I went down for the afternoon session, presented by Corinne Tual. This was much more technical information about the materials used, both originally and to effect the stabilisation and restoration of the paintings. There was quite a lot of chemistry as Corinne told the twenty or so assembled in the little chapel about the types of pigments used and how lime in various guises is used to repair gaps and holes. In typical fashion for the era c. 1500 the main pigments are red and yellow ochre, which can additionally be mixed with each other to produce orange, or with the lime to produce pink.
She made the point, as professional wall paintings conservators always do, that our chapel is not decorated with frescoes, but with with wall paintings ie, painted on dry plaster, not wet, and therefore less well adhered to the walls. All painted wall decoration of the 15th and 16th centuries in this area is painted on dry plaster. No one is sure why local artists switched from mostly working in the true fresco technique in the 12th and 13th centuries to exclusively painting on dry walls a couple of centuries later. Perhaps the techniques of true fresco were lost, but that seems unlikely, and fresco reappears in the 17th and 18th centuries.
Even with conservation the old water damage to the vault is obvious.
For the moment the danse macabre has been gently dusted and any really fragile bits have been covered with Japanese paper. Later, once funds have been raised, these areas will be injected with a glue made from casein that will bind to lime. Importantly, this process is reversible, so that if a better technique is developed it can be applied without risk to the artefact.
Japanese paper holding a portion of wall painting on.
Corinne's presentation was really good. The visitors were really impressed by the technical details and how patient and thorough the conservators have to be. Afterwards she was surrounded by a group with eager questions -- how do the conservators decide what to do in areas where the decoration is missing? are they expecting to find further paintings under the render? does the moisture in the lime mortar used to fill in holes affect the original pigments? (Answers: every little area is treated on a case by case basis, looking carefully at faint traces and remains and at similar areas on other parts of the wall, the aim being to improve 'readability' of the decoration, without making anything up; no; no.)
For now we don't have the funds to conserve the danse macabre any further, but it is protected and can sit as it is indefinitely. Corinne says that it is a couple of months work to conserve once the funds are available. So if you would like to donate to the cause, please get in touch and we will let you know how you can currently contribute.