The Versatility of Oil Paint
Oil paint was not suddenly discovered but instead evolved through the 15th century. Previously, painters had known that it was possible to obtain a greater softness of transition in handling from the egg-bound tempera paints they used by adding small amounts of walnut oil. As the century progressed, first Flemish artists, such as Jan Van Eyck, and then Italian, such as Antonello da Messina, made this addition routine to make their paints capable of capturing the richness and variety of a developing artistic sensibility.
The pre-eminence of oil paint amongst artist paints since then is explained mainly by its susceptibility to so many different modes of application and combination, from the glazes of the 15th century to the striated impasto of late Titian to the thin stain-like veils of Goya.
1. Choose the Support Carefully
A support is whatever material onto which the paint of an artwork, including the primer, is applied. Slate, marble, copper, aluminium, glass, and paper have all been used with some success as supports for oil paint. The most used materials for the last 500 years have been wood and canvas.
Generally speaking, a good support should have three characteristics:
- Absorbency - it should microscopically draw in a slight amount of the liquid binder of the paint.
- Tooth - it should have a slightly rough surface to allow the binder, when dry, to lock into it.
- Stability - in its dried state, it should be subject to no more movement than the paint it supports.
2. Prepare the Support to Suit the Priming
The priming can be defined as the liquid application that, when dry, to some extent isolates paint layers from the support. There are three kinds of primer in everyday use for oil painting:
Oil-Based: Essentially a layer or two of oil paint made more matt than tube colours. A preliminary layer of size is always needed when applying an oil primer to an absorbent support.
Gesso: A size-bound white paint often applied in three or more layers to rigid supports such as wood. Gesso requires a preliminary layer of sealant size.
Acrylic: The most recently devised of the standard primers. Acrylic primer should NOT rest on a size layer; such a coating would damage the primer's adhesion to the support. Remember that whilst an acrylic primer can be overpainted with oil paint, acrylic paints CANNOT be applied successfully to an oil primer.
2.5 Preparing Sealant Size
A semi-absorbent layer of size is necessary for both oil and gesso primings. The dry size is generally added to water in the ratio 8 parts water to 1 part size and allowed to soak overnight.