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Collection Conservation

Painting Conservation

 

Enzo Cucchi's Il vento dei galli neri

 

Enzo Cucchi Ii vento dei galli neri, 1983, oil on canvas, Collection of the National Gallery of Australia Enzo Cucchi Ii vento dei galli neri, 1983, oil on canvas, Collection of the National Gallery of Australia more detail

In 1983 the National Gallery of Australia acquired Enzo Cucchi’s large, recently completed painting, II vento dei galli neri (The wind of the black rooster). In the years since 1983, the painting has required two conservation treatments to secure flaking and cleaving paint. How can such a recent painting need such regular attention? Work by the Gallery’s paintings conservation section has provided some answers.

Ii vento dei galli neri is painted on a double thickness of canvas — two open-weave linen canvases glued together by the artist with a priming of his own composition. With the canvases pinned to his studio wall, Cucchi applied thick and luscious paint in an energetic manner.

Prior to shipping to Australia, the painting was mounted on a folding stretcher. Artists like Cucchi, with studios located upstairs in buildings and generally with limited access, often use folding stretchers when working on large paintings so that, when completed, the works can be easily removed from the building. Folding stretchers are constructed in two sections and held together with wood or metal plates. To fold the painting, the tacking edges at the top and bottom adjacent to the joined sections of stretcher are released. A cardboard cylinder is positioned across the centre of the painting and one half of the stretcher is swung up and over the other. The two sections are kept apart by cleats fixed to the edge of the stretcher sections. Evidence of the folding of the Cucchi painting can now be seenas fractures and wrinkles in the paint at the centre top and centre bottom edges.

 

detail: paint cleavage, upper left detail: paint cleavage, upper left more detail

detail: paint cleavage, wing of rooster detail: paint cleavage, wing of rooster more detail

On arrival at the National Gallery. II vento dei galli neri was unwrapped and unfolded, and the two sections of the stretcher re-joined. The rich aroma of oil paint emanating from the work confirmed its newness.

While indicative of an energetic approach by the artist, thickly rendered paintings often have characteristic conservation problems. Oil paint dries by a complex process. Initially, solvents, such as turpentine evaporate, leaving the paint touch dry This part of the process was still occurring when II vento dei galli neri arrived at the Gallery A much longer process of oxidation follows the initial drying phase where the oil paint absorbs atmospheric oxygen. One problem with thick oil paint is that the surface layer, with ready access to atmospheric oxygen, completes the drying process relatively quickly. The dry upper paint then retards the process by denying sub-surface layers access to oxygen. The complete drying of thick oil paint may take several years. The unevenness of drying creates stress within the paint structure that can lead to cracking and cleavage where paint peels away from the priming. It is this process that is, in part, now contributing to the need for regular conservation maintenance of II vento dei galli neri

The other key to the deterioration of the paint structure lies with the nature of the priming formulated and applied by Cucchi. The priming has been used both as an adhesive, to bond the two canvases together, and as a preparatory layer for his paint. The priming has been trowelled onto the canvas with a strip of wood and is particularly thick and smooth.

During recent conservation treatment, samples of the priming were collected by David Wise, of the University of Canberra, and subjected to a series of analytical tests including Raman microscopy, where the sample illuminated with a laser and the resulting spectra analysed. The priming was found to be composed of diatomaceous earth and oil. Diatomaceous earth is not actually an earth as ochre is an earth, but fossilised diatoms - microscopic unicellular alga with a siliceous cell wall. Diatoms are found as plankton and form great fossil beds in certain parts of the world. Diatomaceous earth has a high porosity and is widely used as a filler and flattening agent in paint. The problem with using a priming composed solely of diatomaceous earth and oil is that it never solidifies to a hard, cohesive layer. The consequence of this for the Cucchi painting is that the priming is not strong enough to counter the stresses that developed in the paint during the long drying process.

microscopic cross-section of sample taken from edge of painting microscopic cross-section of sample taken from edge of painting  more detail

Close examination of the underside of fragments of cleaving paint on II vento dei galli neri revealed a fine layer of the priming: the flaking and cleaving was occurring within the thick priming and not between the paint and priming layers, When extensive flaking and cleavage occur in oil paintings on canvas, one treatment to stabilise the paint structure and re-adhere the paint layer and priming to a canvas is to infuse an adhesive through the reverse face of the canvas. This process was not an option for II vento dei galli neri as the presence of two canvases and a thick priming would restrict the movement of an adhesive through the subsurface layers. Treatment to stabilise areas of flaking and cleavage on the Cucchi painting is, therefore, limited to localised applications of adhesive.

Conservation work undertaken in 1994 and in 1999 has stabilised areas of deterioration, but the inherent structural fault in the painting means that treatment of II vento dei galli neri will be a regular occurrence.

Prior to the recent treatment, a thorough examination of the painting identified numerous areas requiring attention. These were marked on photographs of the painting for future reference. After some basic testing, it was decided to use an acrylic emulsion adhesive to re-attach the areas of loose paint to the underlying priming. The adhesive bonded well to both the paint and priming and could be applied beneath cleaved fragments of paint with a brush or syringe. To aid the re-positioning of cleaved fragments of paint, modest heat from a hand held hot airgun was used. This treatment, combined with the moisture present in the acrylic emulsion, was successful in allowing areas of paint to be gently pushed back against the intact layer of priming. In some areas, small weighted bags were used to bold paint in position until a secure bond between paint and priming was achieved. The process of re-attaching the cleaved paint took several weeks.

 

microscopic cross-section of sample taken from edge of painting microscopic cross-section of sample taken from edge of painting more detail

Following the consolidation process, our attention was directed towards reducing movement of the canvas support. It was felt that vibration and sagging of the canvas on the stretcher may accelerate the process of paint delamination. Oil paint survives best on a rigid, stable support, so the canvas was tensioned with the stretcher keys. This revealed some inadequacies in the strength ofthe stretcher braces. The tension on the canvas was reduced and strips ofaluminium box section were attached to the stretcher braces to provide additional rigidity to the stretcher. The painting was once again tensioned to the desired firmness. To further reduce vibration of the canvas, padded backboards were fitted to the stretcher. It is anticipated that these procedures will extend the period between future conservation treatments.

The conservation treatment of Enzo Cucchi’s II vento dei galli neri demonstrates how an artist’s technique can impact on the long-term stability of a work of art. It demonstrates, too, that the work itself may impose limits on options of treatment available to conservators. This characteristic, referred to as inherent fault or inherent vice, cannot be corrected, but can be managed by conservation treatment. Artists have always experimented with materials and techniques, sometimes with success, sometimes with adverse consequences to their works. While II vento dei galli nerifalls into the latter category, this does notdiminish our appreciation of the work. The rich, dark imagery of the black rooster rising from the arena will remain, thanks to timely conservation intervention. Staff involved with me in this project were Kim Brunoro, Sheridan Roberts and Greg Howard.

Allan Byrne

 

First published in artonview 20 Summer 1999-2000