Oil painting their fingers. Oil painters traditionally applied paint in layers known as "glazes", a method also simply called "indirect painting". This method was first perfected through an adaptation of the egg tempera painting technique, and was applied by the Flemish painters in Northern Europe with pigments ground in linseed oil. More recently, this approach has been called the "mixed technique" or "mixed method". The first coat (the underpainting) is laid down, often painted with egg tempera or turpentine-thinned paint. This layer helps to "tone" the canvas and to cover the white of the gesso. Many artists use this layer to sketch
Oil production plant Sometimes the produced oil may be "stabilised" (a form of partial distillation) which reduces vapour pressure and sweetens "sour" crude oil by removal of hydrogen sulphide, thereby making the crude oil safer for storage and transport. The production plant is said to begin after the production wing valve on the oil well. The product from each well is piped through the choke valve, which regulates the rate of flow. The flowlines are gathered at the inlet manifold and routed into a separator, which will separate the three components. Once the oil has been separated from the gas and produced water,