When I started Oil Painting there were no ready prepared surfaces for painting. Stretched canvas was of course available but out of the question because of the price. To produce enough painting surfaces to experiment with and try out different techniques you had to produce your own. This was a tedious and time consuming job. Wooden boards like wallboard was a popular painting surface but would ‘buckle’ at larger sizes not to mention the weight. The most critical part of the process was ‘sizing’ or sealing the surface. If the surface is too absorbent the oil in the paint will soak in leaving a dull colour similar to gouache. The beauty of oil painting is the brilliance of colour achieved by keeping the dry powder pigment (from which the paint is made) perpetually wet in oil. The oil then hardens as the painting ‘dries’.
Nowadays, there are prepared surfaces from various manufacturers for oil painting. Most are too absorbent. They are sold as suitable for oil or acrylic painting. Whatever about acrylic these will ‘kill’ an oil painting. I have been experimenting with various ‘sizing’ materials in an attempt to rescue the numerous pads of prepared surfaces I have acquired over the years. PVA, a sealant for concrete prior to painting looks promising. It is resistant to the chemical corrosiveness of cement so the mildly acidic nature of oils should be OK and it dries to a waterproof skin. If Leonardo da Vinci had sealed and protected the paint from the caustic elements of the plaster in his Last Supper mural it would not have deteriorated as quickly as it did. Apparently, in his own lifetime the paint was beginning to flake off. PVA, of course, is a recent invention and obviously not available to Leonardo.
A quick test of the suitability of an oil painting surface is to place a drop of Linseed Oil on the surface and leave it for a few days. It should harden to a glossy patch. If not, it will be because it has soaked in completely, leaving a matt, straw coloured stain. No good for oil painting.
This work of ‘modern art’ is a photo of part of the ‘sizing’ experiment. You can see the difference in the gloss on the paint strips. The piece of canvas was ‘sized’ with increasingly more concentrated PVA (mixed with water) going left to right. At the extreme right is 100% PVA. This part is still ‘wet’ but the rest of the strips are already ‘dry’ due to the absorption of the oil in the paint. What you probably cannot see is the ‘richness’ of the colour in this area. Hopefully it will ‘dry’ (oil harden by oxidation) and still retain this richness of colour.
More about this in the future.