Summer 2000 Issue 35
Wolbers' Course - A Review
Following on from a suggestion by Senior Furniture Conservator Shayne Rivers, Richard Wolbers was invited to the Museum to give a course on his cleaning methods, funded jointly by the Conservation Department and the RCA/V&A Conservation Course. Richard Wolbers is an Associate Professor on the Winterthur/University of Delaware Program in Art Conservation in the U.S.A. He is also a practising paintings conservator. For the past twenty years or so, Wolbers has been developing cleaning methods that involve making solvent and water-based gels which are engineered to act in a way specific to the problem at hand.
The course was held over five days, from the 6th to the 10th of March inclusive. The morning sessions were held at the V&A and at the RCA and consisted of lectures from Wolbers on the chemistry behind his methods. (Most participants had attended a series of pre-course lectures on basic chemistry and Wolbers' theories, given by RCA/V&A Conservation Director Professor Alan Cummings and Shayne Rivers in February.) These morning sessions were followed by practical sessions at the V&A's off-site store, Blythe House, in the afternoon. Some twenty six people attended Wolbers' morning lectures, with the afternoon practical session limited to twenty. Those attending the practical sessions were asked to bring along objects or mock-ups on which they could try out a variety of what, at first, seemed rather arcane recipes.
The first morning began with Wolbers questioning why conservators from different disciplines use methods and materials which are often thought of as being mutually exclusive. Paper conservators avoid the use of surfactants; textile conservators use them. Are there really valid reasons for these anomalies? The precedent was set - we would be required to think during this course! Wolbers then went on to give a general introduction to the theory of his cleaning gels. An initial and vivid case-study was described involving the treatment of a nineteenth century oil on canvas painting. This object was unvarnished but covered in a heavy layer of surface dirt and grime. Wolbers' approach to this cleaning problem was as instructive as the final choice of reagents.
What is dirt? Answer: mixture of organic and inorganic materials (e.g. carbon, iron oxide etc) of different particle sizes. If the particles are greater than one micron in diameter then water alone is probably sufficient to remove them. If less than one micron, the bonding is not just electrostatic and the dirt is more difficult to remove with water and mechanical action alone. We may need chelating agents and/or surfactants. At what pH should we be working? Oil films can be more readily broken down at alkaline values. Pigments may be affected at acidic values. Therefore we need to buffer the solution in order to control its possible affects. Cleaning can easily leave behind an electrically charged surface which would attract more dirt. So we also need to take into account the conductivity of the materials involved. Ideally surface pH and conductivity readings should be taken before proceeding with the making of the alchemical potion.
As the week progressed and our understanding increased, the reasoning behind the choice of ingredients became much clearer and less mysterious. A typical recipe may consist of a solvent, a buffer, a salt, a surfactant, a chelator and a thickener. The other morning sessions were spent going over, in great detail, the thinking behind each genre of ingredient. Some people found this a little repetitive and felt that more time could have been devoted to practical work. However, most people found that the repetition was actually very useful in grasping the, at times, complicated chemistry.
The afternoon sessions at Blythe House were very useful although the space available proved somewhat inadequate especially considering the number and variety of chemicals that were in use at any one time. At certain times it seemed that everyone was vying for Wolbers' attention concurrently - but he managed to cope with this very well. Most people had the opportunity to make and try out water, solvent and enzyme based gels with varying degrees of success. More importantly the exposure to the Wolbers' methods gave one confidence to try out previously unexplored approaches. Further, the course proved once again the benefits of inter-disciplinary learning. Tomorrow we turn lead into gold…
Wolbers, R., Sterman, N. and Stavroudis, C., Notes for the Workshop on New Methods in the Cleaning of Paintings, Getty Conservation Institute, 1990.
Lang, S., A Review of Literature Published in Response to Wolbers' resin Soaps, Bile Soaps and Solvents Gels, Final Year Research Project, RCA/V&A Joint Course in Conservation, 1998.
Lang, S., Not So New Methods of Cleaning, V&A Conservation Journal, No. 32, pp15-16
Wolbers, R., Aqueous Methods for Cleaning Painted Surfaces, edited by J. Townsend published by Archetype Books, London 2000
I would like to thank participants in the course for their feedback, reflected in this review. Special thanks to Richard Wolbers and to Shayne Rivers, Alison Richmond and Abigail Wright for organising the venues and materials.