Flemish painter Jan van Eyck (1390-1441) is credited as being the first painter to use the technique of oil painting in his work. His 1434 wedding portrait of Giovanni Arnolfini and his wife, which is now in the National Gallery in London, is accepted by historians as the first and best sample of an oil painting. After him, Antonello da Messina, Leonardo da Vinci, and several others improved the technique to aid faster drying and improve its richness and flexibility. Among the most famous oil paintings are Leonardo da Vinci’s Mona Lisa, which is an oil on a poplar wood panel, and Raphael’s La Donna Velata, also on a wood panel.
Artists who paint with oil use brushes made of different materials to express varying degrees of intensity in their paintings. Eyck used a brush made with a hog’s bristle when he wanted his strokes to appear bold. He used a brush made of squirrel fur when he wanted to paint finer, softer strokes. He used what was called a filbert, or a pointed brush, for detailed work, and a fan brush when he wanted to apply large swaths of paint. Sometimes he even used his fingers.
While each painter’s brushes varied depending on the character and intensity of their paintings, most artists painted in layers while making an oil painting. They first laid the background and left it to dry. Next, they painted the main characters in rough tones. When this second layer dried, the artists brightened the painting with bolder colors, shadows and light effects. In the end, they coated the painting with varnish, which served as a sort of seal that held everything together.
A classical painting took months to complete, but today the process is much faster, what with improved oils with drying agents that firm up paintings in days, not weeks.