Artwatch UK

From the Horse’s Mouth: Seventy years of worthless “science” and reassurances on the safety of picture cleaning solvents

7 February 2014

In our post of 4 February 2014, we challenged the “conservation science” said to have delivered absolute physical safety and absolutely aesthetically and historically correct recoveries of the original condition of pictures during restorations at the Louvre. How could this be so, we countered, when directly comparative photographs recording the pre and post-restoration states of Leonardo’s “The Virgin with Child and St. Anne” showed such clear evidence of injuries? At the time of that controversial 2011 restoration (which prompted resignations by two leading authorities from the restoration’s own advisory committee) we were assured that the Louvre’s varnish removal techniques were so advanced and precise that an imperceptible microns-thin film of original varnish had been left in place. How, therefore, it was asked, could the restorers possibly have damaged the painting? This is a common ploy and we were no more persuaded by it than we had been twenty-five years earlier when restorers of Michelangelo’s Sistine Chapel ceiling claimed to have left a thin protective layer of “original patina” on the ceiling.

To the contrary, we held that when claimed “science” conflicts with the evidence of our eyes, the eyes should have it:

“The currency with which artists work is values and the relationships between values. Through these they work by eye to produce artefacts which fix and carry their intentions, so that they might subsequently be optically apprehended by others. In the production of a painting, every last feature is a product of thought. But every judgement, evaluation and adjustment is transmitted exclusively through human sight, and not, as techno-conservationists might prefer, through sub-atomic particles of matter, complex chemical formulations or other mystifying hi-tech red herrings.”

We reminded viewers of the butchery – no other word suffices – witnessed during the cleaning and repainting of a Veronese head at the Louvre. When that “restoration” was challenged, the Louvre’s restorers made a second (this time secret and unrecorded) attempt to put matters right. They failed and grossly compounded the original blunder (see the lower sequence of photographs at Fig. 3). On such a track record, we suggested, it was surely provocative of the museum to announce not only another Leonardo restoration (his “La Belle Ferronnière”), but even a desire to restore the desperately fragile “Mona Lisa” (details of the mouth of which we show at Figs. 1 and 2).

Yesterday evidence came in that suggests that some restorers may now be doubting their own earlier propaganda. The new (January 2014) issue of the IIC’s journal Studies in Conservation – which describes itself as “the premier international peer-reviewed journal for the conservation of historic and artistic works” – is devoted to “paintings…a subject that has been discussed in publications over many years and frequently”. Indeed it has – and this issue contains a bombshell for much of that earlier research and its implicit reassurances.

It is contained in an article titled “Parametrization of the solvent action on modern artists’ paint systems”. For long-term students of such “Technical Art History” studies, the article begins with what can only be considered a professional confession:

“Effective and responsible use of solvents is an essential skill of a conservator or restorer. The complexity of the solvent processes in the field of conservation/restoration arises from the intent to selectively remove surficial components of a paint build-up without affecting underlying strata. High demands are thus set on the restorer/conservator with respect to specific knowledge on the dissolving properties of a wide range of materials. Owing to the complexity of the solvation and dissolving processes several approaches have been made to simplify solvent action and deliver some selection criteria to the restorer. The ternary ‘Teas chart’ (Teas, 1968) is the most widely applied solvent classification scheme in conservation…even though the system does not permit the prediction of material solubility. With the ternary Teas chart it is not possible to map the solvent action quantitatively…This is due to the fact that the system ignores important intermolecular intereactions. With this simplification, the relation of the individual paramaters to the total strength of interaction is lost. In addition, while this system describes the solvents’ properties, it does not deliver information on material solubility.” (Emphases added.)

Well, so much for that Great White Hope of restorers over the last forty-odd years. In conservation’s technical literature, confessions are delivered only when fresh technical hopes and promises are to hand (as in Fig. 8). And, thus, here we find: “It is a first step towards the development of a systematic tool aimed at the responsible and reliable use of solvents in the field of conservation/restoration.” A bit late in the day for a “first step” towards responsible and safe practice?

Michael Daley

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Above, Figs. 1 and 2: Details of the mouth of Leonardo’s “Mona Lisa” showing the badly fractured “topography” of the paint and varnish layers. In view of the results shown below of the recent cleaning of Leonardo’s “The Virgin and St. Anne”, it is impossible to consider the prospect of a restoration of this painting with anything other than absolute dread. By what means might an attempt be made to separate the infinitely subtle brown modelling of the mouth from the ancient varnishes in which they are presently incorporated?
Fig 3: The cover of the Artwatch UK members’ journal which discussed recent botched restorations at the Prado and the Louvre
Above, Figs. 4, 5, 6 and 7: Comparative details of St Anne in Leonardo’s “The Virgin and St Anne” showing the head before and after its recent “cleaning” and “restoration”. In each pairing, we see more substance, more shading, more modelling before the “technically advanced treatment”.
Above, Fig. 8: Above: an advertisement in Studies in Conservation, the journal of The International Institute for Conservation of Historic and Artistic Works, Volume 42, Number 4, 1997.
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