The purpose of conservation work on the Buell Mullen murals in the SFU Theatre lobby was to remove dirt and corrosion products, repair loss and damage to paint layers, and to restore the collage elements to their original settings. The materials and techniques used by the artist as well as major condition issues were described in Part 1 in the previous issue of Preview.
Detail before and after cleaning: top shows clean section, below, dirt and fingerprints remain
The two stainless steel murals were covered in a thick layer of dust and grime and an initial vacuum of the works with a soft brush removed only the surface dust. Aqueous cleaning was necessary to remove decades of food, drink, cigarette smoke and other accretions for which a three-part method of treatment was developed.
During the first step of cleaning, conservators used a mild conservation-grade detergent to dissolve food particles and remove tobacco residue. Next, a 1% diammonium citrate solution was used where areas of red and orange corrosion, caused by water leaking from the ceiling, required a more powerful cleaning method. The two solutions were each applied with a soft cloth in a circular motion and were then rinsed with water
The final step was to use a gel to remove stubborn areas of corrosion and uneven patina. The gel, a low pH solution of hydro-oxycarboxilic acid, was applied with a soft brush and allowed to work overnight under a plastic wrap. A final rinse with warm water and a squeegee left the stainless steel surface sparkling and streak free.
Next, damaged paint was repaired using several layers of a conservation-grade resin called B-72. Several thick layers were applied without pigment to mimic the thick texture of the epoxy resin used by the artist. A final layer of B-72 mixed with Gamblin Conservation Colours was used to match the in-painted areas with the original paint colour.
Finally, the missing collage elements were replaced with new materials sourced at local gem and lapidary suppliers. Before they were applied, areas of old epoxy that had yellowed and become unsightly were removed using a scalpel blade and a solution of ethanol. The new collage elements were then applied using a grade of epoxy resin less likely to become discoloured and to lose adhesiveness.
The results of the conservation work were quite remarkable; both murals looked clean, intact and considering their age, as close as possible to their original condition. Some areas with mild scratching and abrasion marks, where chairs had been placed against the murals, were, unfortunately, the only type of damage for which there was no easy treatment. Once the theatre renovations have been completed, physical barriers will help prevent further damage and keep the newly-restored murals clean for many years to come.
Previously: Theatres of the World: the conservation of two murals in the Simon Fraser University Theatre, Part 1.
Next issue: Richard Wolbers on cleaning