Bill Martin's Guide to Oil Painting
When You Need the Paint to Flow More
Medium is a term used to describe the liquid that is mixed with the pigment. Oil and pigment make oil paint. If more liquid is added to a color it will flow more smoothly and become more translucent. In most cases the paint consistency right out of the tube is perfect. Small detail, line work and sharp edges, however, are easier with a little additional medium.
Adding linseed oil alone to a color will increase the flow but won't give the sharpest edges. Adding thinner alone gives sharp edges but a chalky appearance. A medium of HALF CITRUS THINNER AND HALF LINSEED OIL is best for most situations.