http://www.kunsthaus.ch/en/the-collection/conservation/examples-from-the-world-of-art-conservation/beginning-of-the-investigative-phase-and-outlook/?redirect_url=title%3Dper%D0%93%C2%A7age

Kunsthaus Zürich

Progress report:
October 2010 to April 2011

Beginning of the investigative phase

At the beginning of January 2011, the ‘practical control phase’ of the project began, during which the methodology that had been previously developed was tested on eight plaster sculptures. This allowed the workflow to be adjusted and the catalogue of working steps to be extended.

Discussions with plaster specialist Rolf Fritschi and bronze caster Peter Zollinger (Bischofszell, canton St. Gallen) helped to resolve outstanding questions and understand cases where contradictory indications had led to uncertainties of interpretation. Materials analysis will be used from now on to back up hypotheses.

The Cintiq Interactive Pen Display, produced by Wacom, was purchased for the mapping of damage and any conspicuous features relating to the materials or techniques used by the artist, and to simplify and standardize the representation and specification of certain phenomena, but also to distinguish between damage and traces left by the artist – thus enabling appropriate restoration measures to be identified.

A particularly pleasing development occurred at the end of the first six months, when the plaster sculpture Homme Chiavenna 1 (1964) was examined using 3D X-Ray CT at the Empa in Dübendorf. This involved the sculpture being scanned while in its transport crate, i.e. without having to be touched. Using this method to compare the surfaces of two ‘identical’ objects is too expensive. However, in this case the procedure revealed some astonishing details about the inside of this particular work: there was a metal reinforcing rod buried in the plaster, and the nose had broken off during demoulding. Furthermore, the procedure seemed to confirm suspicions that the sculpture had been worked on by the artist after casting. It is now also possible to provide advice about possible weak areas that should be given special attention when handling. As shown in the illustration, there is a metal structural support (blue) inside the sculpture. Knowing the exact position of a structural support enables us to identify weak areas. With the sculpture Chiavenna I, for example, it is clear that internal wires are too close to the surface, i.e. they are not imbedded deeply enough in the plaster and are therefore not fulfilling their stabilizing function in these areas. The area around the nose referred to earlier also conceals an old repair and should be treated with extra special care during handling (see fig. 9).

Figures 9 and 10 show air bubbles in the plaster (coloured greenish and brownish). This provides additional information on the (in)homogeneity of the material, which can be useful for subsequent conservational evaluation. Furthermore, data acquired can also be used in connection with preventative measures, such as the construction of appropriate transport packaging.

The team’s work, as well as meetings with experts and the trip to the Empa in Dübendorf, are being followed by filmmaker Roy Oppenheim, who is documenting the entire project with a film that will be approximately 50-minutes long.

Outlook

The development of the methodological approach and the form of documentation have already been largely determined. Eight objects have now been systematically examined and catalogued. The remaining 70 objects will be gradually examined over the coming one and a half years.

Sifting through the written documentation that is still available should provide further illuminating information regarding the history and production of these plaster works. In individual cases, it would also make sense to make cross-comparisons with bronzes and to carry out materials analysis.

Fig. 6: Front view of the clay model used in a series of experiments. © 2011 Kunsthaus Zurich
Fig. 6: Front view of the clay model used in a series of experiments.
© 2011 Kunsthaus Zurich
Fig. 7: Detail of a test object (head) during demoulding of plaster from plaster. © 2011 Kunsthaus Zurich
Fig. 7: Detail of a test object (head) during demoulding of plaster from plaster.
© 2011 Kunsthaus Zurich
Fig. 8 shows (from left to right): Plaster casting from clay model, 1st and 2nd casting from a gelatine mould. ©2011 Kunsthaus Zurich
Fig. 8 shows (from left to right): Plaster casting from clay model, 1st and 2nd casting from a gelatine mould.
©2011 Kunsthaus Zurich
Fig. 9: Back view showing position of supporting structure (blue) and distribution of air bubbles in the plaster (green, brown). (GS 334 © 2011 EMPA Dübendorf)
Fig. 9: Back view showing position of supporting structure (blue) and distribution of air bubbles in the plaster (green, brown).
(GS 334 © 2011 EMPA Dübendorf)
Fig. 10: Side view from the left showing the structural support (blue) and distribution of the air bubbles in the plaster (green, brown). (GS 334 © 2011 EMPA Dübendorf)
Fig. 10: Side view from the left showing the structural support (blue) and distribution of the air bubbles in the plaster (green, brown).
(GS 334 © 2011 EMPA Dübendorf)