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 shale per year. It would produce 290,000 tonnes of shale oil and 75 million cubic meters of oil shale gas per year. The cost of the new oil plant is approximately 3 billion Estonian kroons (€191.7 million, US$264.2 million). The construction was launched in the second half of 2009, and the new Enefit280 plant was commissioned in 2012. The first barrel of shale oil was produced in the new plant on 20 December 2012. 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