Oil painting describes a painting method that uses oils to bind colours and make them stick to the medium that is to be painted. The paint’s coloured substance is mainly in the form of an organic or mineral-based powder known as pigment. This powder is mixed with drying oils (either linseed, walnut or poppy seed) which act as binding agents. This produces a thick, viscous substance which can be used after adding a thinner to make it a fluid consistency. This can be turpentine, lavender or rosemary oil, or else petroleum distillates such as white spirit. Varying amounts of thinner give translucent coats of paint which can be layered to give a glaze and create the effect of depth.
Oil paint is applied to wood or canvas that has previously been prepared with glue and plaster and then scraped off. The oil makes the paint resistant to water, petrol, and alcohol once it has dried, as it does not evaporate, but instead oxidizes and forms a solid layer. The drying time is lengthy but this also allows the painter to go back to his work and modify it at leisure.
The oil painting method has been well-known since Antiquity, but tempera was preferred until the 15th century, when oil painting was perfected by Flemish masters: oil was no longer used as a final protective coat, but gradually integrated within the technique.
