Oil painting is the process of (1) painting with pigments with a medium of (2) drying oil as the binder. Commonly (3) used drying oils include linseed oil, poppy seed oil, walnut oil, and safflower oil. The choice of oil imparts a range of properties to the oil paint, such as the amount of yellowing or (4) drying time. Certain differences, depending on the oil, are also visible in the sheen of the paints. An artist might use several different oils in the same painting depending on specific pigments and effects desired. The paints themselves also develop a particular consistency depending on the medium. The oil may be boiled with a resin, such as pine resin or frankincense, (5) to create a varnish prized for its body and gloss. The technique of (6) binding pigments in oil was known in Europe by at least the 12th century.