Mixing your own medium
Oil Paints are made of pigment (the raw mineral or other material that provides the colour) and something called medium. The medium is the oils oil, plus a few other ingredients which help the paint to flow and dry as the artist wishes.
The wonderful Joseph Sheppard 's reipie for mixing oils appears in the early pages of his fantastic book "How to paint like the old masters" Watson-Guptill Publications (September, 1983) .
Amazon now display this page on their website for all to read, so take a look and see for yourself wether this is the medium for you. Simply click here