Blue is one of the seven colours into which the rays of light divide themselves when refracted through a glassprism, seen in nature in the clear expanse of the heavens; the term is also applied to a dye or pigment of this hue.
The substances used as blue pigments are of very different natures, and derived from various sources; they are all compound bodies, some being natural and others artificial. They are derived almost entirely from the vegetable and mineral kingdoms. The principal blues used in painting are ultramarine, which was originally prepared from lapis-lazuli or azure-stone - a mineral found in China and other oriental countries - but, as now prepared, it is an artificial compound of china-clay, carbonate of soda, sulphur, and charcoal; Prussian or Berlin blue, which is a compound of cyanogen and iron; blue bice, prepared from carbonate of copper; indigo blue, from the indigo plant. Besides these, there are numerous other blues used in art, as blue-verditer, smalt- and cobalt-blue, from cobalt, lacmus or litmus, etc.
Before the discovery of aniline or coal-tar colours dyers chiefly depended for their blues on woad, archil, indigo, and Prussian blue, but now a series of brilliant blues are obtained from coal-tar, possessing great tinctorial power and various degrees of durability.
Blue as a colour ranges from green-blue (turquoise) through to purple-blue (indigo).
Alice blue - A very light greenish-blue colour.
Aquamarine - A bluish-green colour.
Azure - A deep blue colour reminiscent of the sky.
Aquamarine - A pale greenish-blue colour.
Bice blue - A medium blue colour
Cambridge blue - A light blue colour.
Cobalt blue - A deep blue colour with a greenish-tint. The colour of old blue glass.
Lime blue was originally a term for the pigment copper blue, by the mid-20th century the term applied to a very cheap form of ultramarine blue pigment, made by grinding the lowest grade pigment with terra alba. Research Lime Blue
Ultramarine is a blue pigment derived by grinding the semi-precious stone lapis lazuli. Ultramarine is also produced artificially from a mixture of silica, chinaclay, sulphur and sodaash, subjected to prolonged calcination. Ultramarine is attacked by acids, but has a good resistance to alkalis. Ultramarine has a good staining strength and opacity in water, but poor opacity and only moderate staining strength in oil. Research Ultramarine
Diatomite is a diatomaceous earth generally found underlying peat in various districts of Scotland. In Skye, at Loch Quire, where large supplies of diatomite were discovered in the 19th century, it is found about 45 cm below the surface, and extends downward for about two meters, and in some places to a much greater depth. Diatomite is principally used for the manufacture of dynamite, its value as an absorbent being fully double that of the ordinary German Kieselguhr. It is described also as extremely well adapted for the manufacture of silicate and ultramarine paints, siliceous glazings, porcelain, boiler-coatings, isolating felt, etc. Research Diatomite
Abbreviations
Research Lime Blue
