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 platform onshore. Subsea facilities are also easier to expand, with new separators or different modules for different oil types, and are not limited by the fixed floor space of an above-water installation. Offshore oil production involves environmental risks, most notably oil spills from oil tankers or pipelines transporting oil from the platform to onshore facilities, and from leaks and accidents on the platform. Produced water is also generated, which is water brought to the surface along with the oil and gas; it is usually highly saline and may include dissolved or unseparated hydrocarbons. The world's deepest oil platform is the floating