The Lining of Calle de la Moreria
Calle de la Moreria
You may remember this painting - owned by Flux Art Conservation - from our previous blog about Documentation. As a refresher, this oil painting by Spanish artist Fermin Santos (1909-1997) was painted with thick impasto over a gray ground and was executed on a thin, open-weave canvas stretched to a 4-membered stretcher with tacks around the edges. The surface is unvarnished and the paint is matte, very dry, and crunchy. The canvas was crispy with minimal flexibility and several tears around the turnover edges, and the tacks were beginning to corrode. The paint suffered from cracking, delamination, and scattered losses of paint and ground layers. All of these factors combined made it a good candidate for a full lining treatment.
Fig. 2 detail, before treatment, raking light
To line or not to line?
Lining, or relining, is the process of attaching a new support, typically linen or other fabric but could also be a hard support such as a panel, to the back of a painting on canvas. Lining was a common practice for conservators prior to the 1974 Greenwich Conference on Comparative Lining Techniques, which marked a major shift in opinion. During this conference, conversations about lining techniques and materials led to discussions about ethical concerns and the irreversible damage that can occur from lining. Methods involving high temperatures and pressure can flatten original brush strokes or impart canvas weave texture into a thin paint film. Impregnation of the lining adhesive such as wax-resin can change the colors of the painting, impact the solubility of the paint, and affect the movement of the canvas. The conference concluded with conservators declaring a moratorium on lining. Today, the decision to line a painting is not taken lightly and conservators will explore every other possibility before proceeding.
Preparation and Treatment
The decision to line Calle de la Moreria was driven by the amount and severity of the tears around the perimeter, the fragility of the paint, and the degree to which the canvas had degraded.
Since the paint was brittle and actively flaking, we decided to start by consolidating what we could using a diluted adhesive followed by a full facing to limit the risk of losing paint flakes during the process. We faced the painting by brushing a weak aqueous adhesive through pieces of tissue, materials that were chosen for their reversibility, flexibility, and ability to introduce moisture into the paint system and help relax the canvas and paint. The blue sky and signature were not faced due to concerns about water sensitivity (fig. 3). Following consolidation and facing, the painting was unstretched and the verso was dry cleaned before it was placed in a custom humidification chamber constructed with PVC pipes and nylon film (fig. 4). The humidification process is meant to relax the canvas and brittle paint allowing it to lay flatter without forming new cracks.
After humidification, the painting was placed face up on a heated suction table sandwiched between silicone-coated paper and Mylar. A twill tape border around the painting under the upper layer of Mylar facilitated even vacuum suction (fig. 5). The warm table and gentle pressure from the vacuum set down canvas deformations and helped to secure the flaking paint.
After the heat treatment, we sized the back of the canvas with a conservation-grade adhesive to aid in the lining process and further consolidate the flaking and friable paint layer (fig.6). Next, we removed the tissue facing with water which also aided in cleaning surface dirt and resulted in a brighter picture overall.
Prepping the lining canvas
Before a painting can be lined, the lining canvas must also undergo extensive preparation. Linen, cut a few inches larger than the original canvas, was stretched on a temporary stretcher with special care taken to ensure the warp and weft were straight. The stretched linen was then wetted, taken off the stretcher, stretched again, and sized with an aqueous adhesive. This process is done to introduce moisture to the linen so that future fluctuations in humidity will have less of an effect on the fibers. Once sized, we used a heated spatula to smooth and flatten the fibers.
The adhesive we chose to bond the two canvases together is a modern, thermoplastic resin designed specifically for paintings conservators. It’s activated by heat at a low enough temperature that won’t damage traditional oil paint and can be reversed in mild solvents that are generally safe for paint. We traced and cut the adhesive film to the exact size and shape of our painting and ironed it onto the center of our prepared lining canvas.
Lining and Stretching
It was now time to line the painting! The hot table was set up the same way as the heat treatment (see fig. 5) and adjusted to the ideal temperature and pressure determined by previous tests.
With the adhesive film adhered to the center of the lining canvas, the painting was placed face up on top of the film. Silicone-coated paper was placed between the tacking edge and the adhesive film to prevent adherence of the lining canvas to the original tacking edges. This technique was employed to allow the delicate original edges to be turned and secured separate from the lining canvas. (fig. 7)
Once the lining process was complete the lining canvas was cut from the stretcher (fig. 8) and placed face up on the original stretcher. The tacking edges of the lining canvas were tacked down in the position most similar to the original orientation (fig. 9 and fig. 10). The original tacking edges were then gently relaxed with low heat and also tacked to the stretcher. Heat was then used to attach the original tacking edge to the lining tacking edge. Blued steel tacks with blotter paper barriers were used to secure the painting to the original stretcher.
Stay tuned for the rest of the treatment!
