Oil paints are very popular because they dry slowly, enabling you to work with the paint for quite a while after you have applied it to a canvas or board. Once the paint has dried, it can be over painted without disturbing the original paint. Straight from the tube, oil paint is thick and buttery. It can be diluted with thinners all the way down to a transparent wash.
Oil Paint
Traditional oil paint comes in tubes. Rather buy quality primary colors and perhaps secondary colors than a range of cheap paints. Some manufacturers produce fast-drying oils in tubes, water-mixable oils in tubes and pans (blocks), and oil bars (paint in stick form, not oil pastels).
Thinners or Solvents for Oil Paints
Thinners are used to dilute oil paint and to clean your brushes and palette. The most traditional solvent is turpentine, which maintains the oiliness of oil paint. Adding white or mineral spirits to oil paints makes a watery mixture. Look for low-odor solvents and always use in a well-ventilated room. Solvents sold in hardware stores are not artist''''''''s quality and can cause yellowing.
Mediums for Oil Paints
Mediums are used to dilute color, increase gloss and transparency, reduce drying time, and avoid over thinning. You can buy ready-mixed mediums or use various forms of linseed oil. Read the description on the bottle to see exactly what a medium does. For very thin washes, mix a medium with thinners, otherwise there may not be enough oil to bind the pigment.
Brushes for Oil Painting
Stiff hog-hair brushes are ideal for thick oil paint. Cheap hog brushes work as well as the more expensive ones; they just do not last as long. Use soft sable brushes, or the cheaper synthetic alternatives, for washes where you do not want brush marks to show. Try brushes with both long and short handles and different head shapes to see which you prefer.
Primers for Oil Paint
Canvas and boards must be primed before being used for oil paints. Oil primers must be put over a coat of size. Primers made for acrylic paints can be used for oil paintings. These dry quickly and do not require any sizing underneath. If you are painting on paper, put down a thin layer of acrylic primer.