The oil painting technique was to become dominant in the 15th and 16th centuries, it has remained as the artists favorite medium only being challenged in the latter years of the twentieth century by the advent of acrylic paint.
Artists working in tempera found that their colours lacked the covering power of oils while the fresco painter was unable to make alterations to his work. Oil provided a versatile medium in which the artist was allowed the freedom to change the composition of his painting.
Because the colour saturation of the paint was enhanced by the use of oil, no other medium could reproduce it's range of both transparency and opacity.
The methods of applying oil paints to a surface have become varied in the extreme; from the traditional use of brushes and pallete knives; to the use of hands and feet; or the splattering of paint direct from tubes and cans; in the modern era it seems that just about anything is used by artists to achieve the desired effect.
During the early renaissance period oil painting was used first by the Netherlandish painters and was eventually taken up by their counterparts in Italy.
The Northern painters preparation was consistent, they used oak panels (or other timbers) with smooth, white chalk grounds. A detailed under drawing was then added and usually made none absorbent by the application of a drying oil.
15th Century Oil Technique circa:-1436. (Northern Art)