Ronald Moore - Fine Arts

Colonel French

This painting has been damaged having dents and holes in it. There is also severe craquelure with cleavage and cupping. This condition often occurs when a canvas is in a high humidity , even for a relatively short time, and the rabbit skin glue size, which seals the bare canvas, becomes softened. It then shrinks on drying out and distorts the paint surface with shallow saucer shaped depressions known as cupping . Craquelure is the name given to the mesh of cracks which covers old oil paintings and which becomes finer and smaller the older the painting. The cellulose in the canvas also expands and contracts as the humidity changes and this causes a general slackness in the canvas as countless changes eventually cause it to expand. The paint surface naturally follows these distortions. There also many other causes of cracking in paint related to supports, mediums techniques and oxidation.
This is greatly simplifying the problem of craquelure and its many causes but in the case of this 19thC painting. simple structural damage and high humidity are the main problems. The case is usually far more complex with earlier pictures.

Painting showing example of the cupped surface,
craquelue and one of several holes in the canvas.

The canvas partially cleaned using a 1:3 mixture
of Isopropyl alcohol and white spirit.

In this case, lining the painting on to a new canvas with a reversible heat activated adhesive is an acceptable solution to the problems given the possible humidity of the castle. Wax resin does imbed its into the canvas and is not always appropriate.
The painting is removed from its stretcher and placed on a new canvas on which the wax resin adhesive has already been melted and evenly spread. Below the lining canvas is a sheet of transparent heat resistant Melinex and another sheet covers the surface. The 7`x5` Willard vacuum table then heats to an even temperature of around 75 degrees and the gentle vacuum pressure on the painting causes the adhesive to be drawn up through the canvas and attach to the lining canvas at the same time. When the process is complete the heat is turned off and a cooling fan switched on.
The now lined canvas is then tacked on to its stretcher with a new natural linen backing .
This again is a simplification of the process.

The canvas has been removed from its stretcher and is on a Willard vacuum lining table. The surface is protected above and below by a layer of Melinex, a transparent material which will withstand the high temperatures .(c. 80 degrees C)

The canvas during lining showing
temperature controls

Once impregnated by the wax resin adhesive, the canvas has been humidified to soften the rabbit skin glue used to prime the canvas and which had distorted the paint to form the shallow dips known as cupping. Once softened by the combination of heat and water vapour, the action of the vacuum will press the canvas flat again and remove the cupping and mitigate the effect of the craquelure. Care has to be taken to ensure that the pressure does not flatten impasto or high areas of paint. If some preventative treatment is not attempted, then in time air born water vapour will access the cracks further until the cupping increases and small flakes of paint will begin to remove from the edges of the cracks.
The canvas is of 12 oz. cotton and the adhesive is 5:3:1/2 bleached beeswax, dammar resin and Ketone Resin N.

Rolling excess wax resin from between the painting and lining canvas.

Stretching the linen backing onto
the stretcher; this is a cosmetic
proceedure so that the new wax is not visible.

Stretching the lined canvas

The lined canvas prior to ironing
down the tacking margin

The completed lining with the three raw materials of the adhesive,
Ketone Resin N, beeswax, dammar resin

Captain James Leatham Painted in 1825

Conservator : Ronald Moore BA (Hons) (Courtauld Institute of Art, London University)
Ronald Moore has started work on many of the paintings and prints including this one of Captain James Leatham Painted in 1825. In the painting you will see that Captain Leatham is wearing his Waterloo Medal.