Oil paint considered drying, those with an iodine number of 115-130 are semi-drying, and those with an iodine number of less than 115 are non-drying. Linseed oil, the most prevalent vehicle for artists' oil paints, is a drying oil. When exposed to air, oils do not undergo the same evaporative process that water does. Instead, they polymerize into a dry semisolid. This rate of process can be very slow, depending on the oil. The advantage of the slow-drying quality of oil paint is that an artist can develop a painting gradually. Earlier media such as egg tempera dried quickly, which prevented the
Narva Oil Plant Narva Oil Plant Narva Oil Plant (), a subsidiary of Eesti Energia, is a producer of shale oil from oil shale. It operates a commercial scale shale oil retorting plant, located in Auvere near Narva, Estonia. The oil shale retorting plant (the UTT-3000 refinery) was built in the late 1970s next to the Eesti Power Plant to provide shale oil as a start-up fuel for the power plants. The plant was commissioned in 1980. Since the beginning of the 1990s, the oil plant operated as a part of the Narva Power Plants. In September 2007, the oil plant was separated