Over the period January to April 1989, two paintings by the artist Hortense Gordon, Colour in Space and Hurricane Motifs from the collection of the Chatham Cultural Centre, received conservation treatment at the Canadian Conservation Institute. Although the paintings were similar in style and fabrication, important differences existed in the type of canvas and ground used by the artist, and in the presence or not of a protective varnish layer. It is interesting to examine these differences in relation to the conservation measures required to stabilize the paintings.

The linen canvas of Colour in Space was in much better condition than the cotton canvas of Hurricane Motifs. The cotton fabric was weak, brittle and torn along the edges. It had also suffered several tears within the central portion of the composition. These tears had been repaired with canvas patches at some point in the past. Numerous labels and inscriptions were present on the reverse of both painting (figures 3 and 4).

As part of the treatment, all labels were removed from the reverse of the canvases. Distortions in the canvas supports were relaxed using humidification and slight pressure or tension. Patches and old adhesive on Hurricane Motifs were removed. Tears were rejoined using a special polyvinyl acetate adhesive. It was necessary to remove Hurricane Motifs from its stretcher and to line (back) the damaged tacking margins with a polyester fabric. The fabric was adhered to the reverse of the original canvas with a special "heat-set" vinyl acetate adhesive (figure 5).

Due to the relatively sound condition of Colour in Space, it was not necessary to remove the painting from its stretcher. It was decided, however, to place a rigid honeycomb-core paper panel directly against that part of the canvas visible from the reverse (figure 6 and Diagram 1). This panel was held in place with small plexiglass strips secured to the reverse of the stretcher bars. The panel provided extra support against which the painting could rest. It also acted as an additional barrier to protect the reverse of the canvas from extremes and changes in relative humidity.

Additional support was provided to Hurricane Motifs in the form of a loose lining—a polyester fabric stretched and secured to the original stretcher. The painting was then resecured to the stretcher so that it rested against this polyester fabric (figures 7 and 8 and Diagram 2).

The ground layer in Hurricane Motifs was weak and crumbly. It softened with water, indicating that it probably contained a glue binder. Paint losses that had and were occurring in this painting resulted from a loss of adhesion between the ground and the canvas. All damaged areas were consolidated by introducing a vinyl acetate resin dissolved in an organic solvent. This was followed with the gentle application of heat and pressure using an electrically-heated spatula to lay down and readhere the lifting paint.

The ground layer in Colour in Space appeared to be a combination of white lead and linseed oil. The bond between the canvas and the ground was still very good. No active flaking or lifting paint was discovered. Paint losses that had occurred were a result of separation between the ground and paint layers.

Both paintings contained an extensive system of cracks through the paint and ground layers. The extent of these cracks in Colour in Space became visible when the painting was viewed by transmitted light (figure 9). In this examination technique, light source is placed behind the painting and the painting is viewed from the front. Light passes through the cracks and losses in the paint layer, making these damages very apparent.

During treatment, a varnish layer was discovered on Colour in Space. Analysis of this varnish by CCI's Analytical Research Services Division revealed it to be n-butylmethacrylate (acrylic). The pristine appearance of the paint layer below the varnish suggested that the varnish had been applied early in the life of the painting, possibly by the artist herself. Over the years this varnish had become embedded with a layer of disfiguring surface dirt. Removal of the varnish was therefore necessary to restore the true brilliance of the colours. Fortunately the varnish dissolved readily in a 1:1 mixture of acetone and mineral spirits applied with cotton swabs (figure 10). The change in appearance before and after removal of the dirt-embedded varnish can be seen in figure 11.