The binder in oil paint is oil. Oil is a substance which can be thick or thinned down using a thinner such as turpentine. So, adding turps to oil paint thins it down from a thick textured paint to a free flowing wash which may be applied easily.
The surface to be used must be prepared properly to achieve lasting results. Canvas must be sized and primed with two to three coats of primer to prevent oil bleeding through to the back of the panting causing the canvas to possibly rot or grow mould over time.
One of the basic rules of oil painting to avoid cracking over time is the ‘fat over lean’ principle. Thin oil washes are applied to surface before progressively thicker paint is applied. If thin, fast drying paint is applied over slower drying, thick ‘fat’ paint, cracks will appear in the painting.
Some artists choose to apply paint thickly with a palette knife directly from the tube, others will paint more fluidly working paint wet into wet. Brushes and even fingers may be used to apply paint. It is possible to paint from lush thick strokes on rough surfaces to fine fluid detail on smooth surfaces.
Transparent glazes and coloured tints are features achievable using oil paints with very effective results.
It takes a minimum of six months for an oil painting to be dry enough to be given a protective coat of varnish and this depends on the thickness of the applied paint and the humidity if the air surrounding the painting. It is usually recommended that a painting be left for twelve months before varnishing.
