Canvas is a strong woven fabric, which can be made from linen, cotton, and other materials such as jute or hemp. Canvas became more popular than wood with nineteenth-century painters because canvas did not split or have woodworms. It was also lighter and more easily obtainable. The natural colour of canvas is brown; it could be bought like this with a thin layer of white paint applied (see images below). This layer of white paint was called the ground. It is interesting to note that because Pre-Raphaelite artists wanted to use very white grounds, colourmen, suppliers of art materials, started to make and sell white canvasses.
Millais bought two pieces of canvas (76.2 x 111.8 cm) for Ophelia from the colourman Mr Charles Roberson on 7 June 1851 for 15 shillings (equivalent to £47 today). Roberson’s stamp on the back of the painting is shown in the image below. This type of painting, with two canvasses on a single stretcher (a wooden frame), one directly under the other, was sold by Roberson’s as a double canvas. The second canvas was used to cover the back of the painting to protect it.
Both canvasses were primed. This means they were covered with a glue solution and a ground. Millais used lead white paint as a ground. He then painted a layer of zinc white to make the canvas even brighter. A cross section of paint from Ophelia under UV light shows the layer of zinc white applied by Millais over the lead white ground prepared by Roberson’s. It also shows that the lead white paint has cracked (see image below).
It is possible that at the beginning of each day Millais would mark out the area to be painted that day by covering it with white paint. He would then be working on a wet white ground, and he would finish this area in detail while other parts of the canvas were still bare. In order to make the most of the bright white ground, he would mix colours as little as possible so that they remained pure, and apply the paint in single layers.