In 1984 during a three week visit to Australia, New York artist, Keith Haring, undertook a number of public art events. In Melbourne these included painting the NGV’s waterwall and completing a mural on the wall of what was then Collingwood Technical School. The NGV’s waterwall project was intended as an ephemeral work and survives through documentation only. The Collingwood mural remains however and is now a much loved and important part of inner Melbourne’s cultural landscape, so much so that in 2004 it was added to the Victorian Heritage Register.
Despite some conservation work that was done during the 1990s the effects of weathering have caused significant deterioration to the mural. In 2010, when management of the Collingwood site was taken on by Arts Victoria, a conservation plan was commissioned. The plan identified the need for urgent conservation work to stabilise the mural and to undertake treatment that would return its visibility and vitality. In 2013, following a tender process, the internationally renowned conservator Antonio Rava was contracted to carry out this work. Now nearing completion I asked Antonio a few questions about his experiences in conserving this iconic work.
DH: The conservation management plan that Arts Victoria commissioned identified consolidation and stabilisation as important parts of the preservation process. What structural issues did you find when you began work on the mural and how did you go about determining the most appropriate course of treatment?
AR: Before cleaning our first priority was to consolidate any areas where the surface was vulnerable. The problems were twofold, one for the red lines which peeled and cracked extensively. It appeared to be a Dulux brand paint, red enamel made with alkyd resins, not suitable to outdoor exposure. The cracking is similar to that which occurs when oil paint is exposed to fluctuations in temperature and relative humidity, which can bring about a rapid deterioration of the paint film. It was necessary in this case to use a nano-phase acrylic emulsion, which was enough for re-cohesion, while for re-adhesion we used a heated spatula set at a moderate temperature of 60 °C, to settle back the peeling fragments of paint.
The second problem was in the lower part of the mural where some flaking areas of plaster showed lack of adhesion to the wall. We treated this by injecting the same nano-acrylic emulsion thickened with clean sand, adding fills at the edges with Gesmonite, a reticular gypsum suitable to exterior exposure. The same material was used for the fills of small losses all over the mural, avoiding any change from the condition of the plaster at the time of Haring paint.
DH: The door, a key piece of the mural which had been missing for almost thirty years, was recently rediscovered. Given that it had effectively been protected from weather damage did it play a part in the conservation process?
AR: The door was a good reference for the change of the yellow of the mural. In fact the door was stolen briefly after the completion of the mural and was kept out of the elements as far as we can detect from its good condition. Therefore we were able to compare, by means of colorimetry the actual colours with those of the mural, which appears slightly paler due to the weathering process. We brought the door to the site to see the final effect of completion of the work where it will eventually be reinstalled. Naturally the chemical analysis showed the same pigments as the mural, and we are sure that it is the original door.
DH: There was a strong push from parts of the community to repaint the mural rather than to conserve it. One of the arguments for repainting was that it was believed that the vibrancy of the original colours had been permanently lost due to exposure to the weather and that conserving the mural would simply stabilise it with little visual or aesthetic benefit. Looking at the mural now that the treatment is near completion I am amazed at how bright and fresh the colours are. Can you describe the process you have used to bring them back to life?
AR: Cleaning of the surface has brought back the vivid colour of the original appearance. Especially the yellow reappeared after the removal of the powdery white surface deposit, which was caused by migration of titanium dioxide. It was possible to clean it mechanically with rubber erasers, gently exposing the original layer of intense yellow. Also the green was improved by cleaning. The red lines were very faded, as one can see from photographic documents, and we glazed these areas using a transparent vivid red paint made of nano-acrylic emulsion and the same synthetic pigment as the original, from Kremer Pigments, Switzerland. Thus we obtained a new balance between the colours regaining the visibility of the paint, but we can still see the brush strokes of the artist under the red transparent glaze. In this way there will be no unevenness in the red, because the glaze was homogeneous over all the red. The reversibility is still theoretically possible because the retouching film has not penetrated into the plaster, since it adheres strictly to the surface, and can be removed with the same rubber erasers, exposing the surface of the paint layer as it was before.
DH: I am aware of the amazing work you did in conserving another of Keith Haring’s murals in Pisa, on the wall of the Chiesa di Sant’Antonio abate. How did the treatment compare with that of the Collingwood mural?
AR: I worked to the Pisa Tuttomondo mural by Keith Haring two years ago with Will Shank, and the main problem was cleaning the surface from the whitening which appeared in that case coming from the calcium carbonate of the plaster, which recrystallized over the surface of Haring’s acrylic colours. This was different from the problem in Melbourne, much more solid and crystalline so we found a special solution with rigid gels of Agar Agar, applied fluid on the surface with the chelating agent EDTA 1% in a water solution. After few minutes the peeled gel contained all the calcium carbonate and the paint layer appeared perfectly cleaned and brilliant.
In Melbourne the white titanium dioxide surface deposit, which was the main component of the chalking surface of the yellow was much looser, but it was similarly insoluble with water or solvents, for the risk of changing the stable condition of the paint. Therefore we opted for a mechanical dry cleaning with erasers which showed to be effective and safe.
DH: Now that you are nearing the completion of the Haring mural what is your next project?
AR: My next project will be the restoration of the Paris Keith Haring mural in the Necker Hospital in Montparnasse, with Will Shank again. It is very damaged and particularly difficult, being painted over a PVA and sand plaster from the sixties, which is peeling and blistering extensively. We still are gathering all the scientific information and we will soon start the first stage of consolidation.