Oil provides artists with a magnificent new type of paint

Easily blended, long lasting, slow drying, and offering a far broader range of colours than had previously been possible, oil paint was one of the cornerstones of the Renaissance artistic revolution.

Artists are as dependent upon the materials they use as they are on their talents, training, and technical skills. Paint is basically tiny particles of colour, the pigment, held together by a binding substance. The two are mixed and applied to a surface when wet then left to dry. Tempera, which is made by mixing pigments with egg yolks or gum, was the main type of paint in use until the fifteenth century. It is easy to imagine the consistency of beaten egg, mixed with coloured powder, and then allowed to dry. It was effective but highly restrictive to use. Colours could not be blended on the picture surface, but were mixed ahead of time, then used swiftly before they dried. The artist had to decide precisely which colour went where, and the speed at which work had to be completed was often achieved only with teams of assistants.

Finding a slower drying, more flexible alternative to the egg was a major challenge. Oil that blended when liquid but hardened when dry seemed the perfect solution. Almond and olive oil proved unsatisfactory because they did not become sufficiently hard. Other oils caused the paint to become too hard and were prone to cracking. Poppy, walnut, and sunflower oil worked reasonably, but linseed oil worked far more effectively than any other. It was easy to blend with pigments, and it dried without direct heat or sunlight to a strong, lasting finish. In addition, colours did not alter significantly when the paint dried. Artists could mix the paint on the surface as they worked, knowing that when they were dry the appearance would be as they intended. This enabled far more creativity, as painters could work with the paint as they applied it.

Oil paint became established first in Northern Europe and was vital to the style of painting that emerged in the Low Countries during this period. Jan Van

12 Portrait of Giovanni Arnolfini and His Wife

Jan van Eyck,1434