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BLUE
Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when observing light with a dominant wavelength between approximately 450 and 495 nanometres. Most blues contain a slight mixture of other colours; azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called Tyndall effect explains blue eyes. Distant objects appear more blue because of another optical effect called aerial perspective. Blue has been an important colour in art and decoration since ancient times. The semi-precious stone lapis lazuli was used in ancient Egypt for jewellery and ornament and later, in the Renaissance, to make the pigment ultramarine, the most expensive of all pigments. In the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue And White Porcelain
"Blue and white pottery" () covers a wide range of white pottery and porcelain decorated under the glaze with a blue pigment, generally cobalt oxide. The decoration is commonly applied by hand, originally by brush painting, but nowadays by stencilling or by transfer-printing, though other methods of application have also been used. The cobalt pigment is one of the very few that can withstand the highest firing temperatures that are required, in particular for porcelain, which partly accounts for its long-lasting popularity. Historically, many other colours required overglaze decoration and then a second firing at a lower temperature to fix that. The origin of the blue glazes thought to lie in Iraq, when craftsmen in Basra sought to imitate imported white Chinese stoneware with their own tin-glazed, white pottery and added decorative motifs in blue glazes. Such Abbasid-era pieces have been found in present-day Iraq dating to the 9th century A.D., decades after the opening of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
