Oil painting is a process by which a drying oil such as linseed oil is used to bond pigments. The technique is said to have been developed in the 15th Century by Jan Van Eyck. In this process, thin layers of paint are applied to a surface using a brush. To come up with a finished product, however, the artist must follow several steps.
The first step would be preparation of the surface. Many different types of surfaces can be used for oil paintings, historically, surfaces such as wood, canvas, paper or slate have been used. My surface of choice is canvas. For custom size works, I first cut the canvas to the right size for the painting that I am working on. I stretch the canvas over a canvas stretcher and staple it to the sides to create a smooth surface. I prime the canvas by painting it with gesso which gives a clean white surface for me to begin with. For standard sizes, I use pre-stretched, primed canvas.
Essential to the painting process are the brushes and the paints themselves. Brushes can be made of natural or synthetic fibers and their use is really up to the artist. Brushes with natural animal hair such as hogs bristle or squirrel fur are preferable to acrylic brushes because their bristles hold paint in a way that allows the artist control over what is being applied to the canvas. An artist may also use a palette knife to apply and/or remove paint from a canvas.
Traditionally, artists prepared their own paints or pigments. The pigment is the natural substance which brings color to the mixture. Some examples of pigments include sulfur for yellow, cobalt for blue, or carbon for black. These pigments are in powdered form and are mixed with linseed oil to form the paint. Today, for convenience purposes, many artists use tubes of prepared oil paints. While this saves on time, quality oil paints are still relatively costly due to the superiority of the paints and pigments involved.
The paint is then applied in thin layers to the canvas. The first layer is called underpainting. This layer is used to cover the white gesso as well as lightly paint the subject. The underpainting layer uses oil paint, thinned with turpentine, to achieve the lightened look. The next layer used is to apply the dark and light color swatches to the canvas. The colors are blended, but shading and detail are not yet applied and the painting still has a flat look to it. The following layers are used to apply the details, shading, and subtleties to the painting. Once all layers of paint are dried, a glaze is applied to seal the surface of the painting. Oil paints can take months to dry fully, but are usually dry to the touch after about a week.
The oil painting process is an extensive one which requires patience and technique. However, oil paints have lasted for centuries and this permanence makes them an ideal medium to use for formal paintings.