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Paintings Conservator in training at SRAL, Maastricht
Masterthesis: Luitsen Kuiper, a conservator's methodology
The conservation treatment practice of Luitsen Kuiper has been researched and is described in this thesis. Luitsen Kuiper (1936-1989) was a Dutch conservator who worked for several collections and museums including the Mauritshuis in The Hague and the Rijksmuseum in Amsterdam. His working practice as a conservator has been reconstructed by researching his treatment reports written by him and by interviews held with his close family members, colleagues and students.
Throughout his working career he carried out some important innovations. He was one of the first conservators who saw the importance of systematical documentation of the performed treatmentssuch as his use of solvents, fillers and retouching media. It was possible to research the products used by Kuiper because the treatment reports written by him have been kept in the archives of the museums in which he worked. These describe both structural and aesthetical treatments carried out by Kuiper at all stages of his career. Later in his career, in the period that he was working for the Rijksmuseum, he championed the use of personal safety equipment whilst working with toxic solvents.
The reports showed that the three solvents mostly used by Kuiper to remove aged varnish and overpaints were ethanol, oil of turpentine and dimethylformamide. Ethanol and oil of turpentine were mostly used for varnish removal while dimethylformamide was used more for the removal of old oil paint retouches. Oil of turpentine was commonly used to neutralise solvents and mixtures. Kuiper thought this could reduce the strong effect of polar solvents like ethanol on the varnish layer and in this way protect the underlaying paint layer against their effects. This was a common practice and it was used also by Helmut Ruhemann, conservator in the National Gallery in London, throughout his career. What they did not know was that a mixture that consists of an aromatic hydrocarbon and a polar solvent can swell the oil paint more than individual solvents used separately. So the neutralising effect of oil of turpentine does not work in this scenario. The reports further show that Kuiper used to line the canvas paintings using wax and resin as an adhesive, the so-called Dutch method. Kuiper continued to use natural productsin the treatment of paintings and stated thatall treatments had to be reversible. He carefully considered the use of synthetic products for this task, which he seldom used. His opinions regarding these are described in a case study about the treatment of a painting by Vincent van Gogh, Selfportrait with a grey hat (1887) belonging to the Van Gogh Museum in Amsterdam . He thought that there was not enough knowledge about the long-term stability and reversibility of synthetic products and thus rejected their use until it was proven that the products were stable enough. Until that point, he would continue to use materials of which he knew were reliable for this treatment practice. International criticism against lining with wax and resin adhesive was known to Kuiper but still he refused to use other products for lining. A second case study, describing the treatment of the Adoration of the Kings (1619) by Hendrick ter Brugghen belonging to the Rijksmuseum, is used to show Kuiper’s respect for the authenticity of a painting and the artist’s intent. It could be concluded that the intention of the artist and thus the removal of all non-original materials to expose the original surface played an important role in his decisionmaking. Old additions, varnish, overpaint and retouchings were fully removed in so far this would not damage the original paint layer. Lacunae in the paint layer would later be retouched integrally. Only large lacunae that were too big to make a reliable reconstruction would not be retouched integrally. This was however not the common practice by Kuiper. According to Cesare Brandi’s theory of restoration the changes that can appear with the aging of apainting become a part of the history of the object and the aesthetic of the artwork and have to remain visible to the viewer. Kuiper and Brandi did not make reconstructions when the conservator is forced to use fantasy to reconstruct missing passages and both accepted differences that derive over time. Only Brandi went further with this than Kuiper, because he proposed that retouches applied should be differentiated from the original paint layer. The practice of his theory is more applicable to fresco’s and early Italian panel paintings. Somebody who had a different ethical approach to Kuiper was John Brealey. According to Brealey the restored painting should appear in balance as the artist’s original intent despite any changes that occur over time. Lighter parts of a painting that darkened less with age than darker passages, were for example toned down or discolored, yellowed varnish was left in the cleaning phase to maintain the tonal balance. As said above Kuiper always removed non-original materials. Both retouched in an integral manner but Brealey went further with this than Kuiper. Kuiper can therefore be placed between the theories of Brandi and Brealey but his approach shows more similarities to that of Brandi.