What is ultramarine? Properties and use of the substance
Ultramarine was popular in the Middle Ages. It was used to create works of art, and the name began to denote a bright blue tint. But what is ultramarine? What does it consist of? Where does it apply? Let's find out.
What is ultramarine: a description of the substance
The name of the substance consists of two Latin words: ultra (above) and marinus (marine). Together, they are interpreted as "oversea", that is, "more blue than the sea." What is ultramarine? It is a colorant created from crushed mineral. Initially, it is a natural material, the basis for which was a semiprecious stone lapis lazuli or lapis lazuli. It really has a rich color, from blue to deep purple hues.
About what is ultramarine, they knew in the Middle Ages. In China, it was used for painting porcelain, in Europe, artists created their canvases with it (Vermeer, Leonardo Da Vinci, etc.).Lapis lazuli for dye was mined in Afghanistan, which was very long and expensive.
In the 18th century, deposits were discovered in the Baikal region, but by that time they had already replaced ultramarine with cheaper and no less bright dyes — Berlin blue and cobalt blue. In the XIX century, blue ultramarine learned to get artificially, using the same components that are present in natural stone. It was much cheaper than the “double”, but practically did not yield to it in quality.
Lapis lazuli stone
Natural material for ultramarine was used as an ornamental stone. Lapis lazulia is considered a semi-precious first-order mineral, along with jade, jasper, labradorite, agate and rock crystal.
The most highly valued stone is dark blue and cornflower-blue flowers, in which white, gray and blue inclusions are absent or unobtrusive. The golden inclusions of pyrite at the same time, on the contrary, give it value.
The mineral is easily processed, has softness and the increased fragility. To make a dye out of it, the stone was ground into powder, cleaned and mixed with drying oil. To give it a richer and clearer shade it was ignited red hot.The main task was not to overdo it, otherwise the mineral lost its color.
Vases and caskets were decorated with blue stone and figurines made of it. Lapis lined with interior details and inlaid mosaics. It can be seen on the columns of St. Isaac's Cathedral in St. Petersburg. Mineral was very popular in ancient Egypt. They were decorated with the tombs of the Pharaohs and inserted into the royal jewelry. In the east, magical properties were attributed to him.
Ultramarine is known as a bright blue mineral paint. It is a powder that does not dissolve in water and organic solvents, it is resistant to light and interaction with alkali. Easily destroyed by acids.
Depending on the composition, it can also be green, red, purple and white. The main components of the substance are sulfur, infusorial earth (amphoraic silica), aluminosilicate and sodium silicate. Formula of natural lapis lazuli mineral - Na6Ca2(AlSiO4)6(SO4, S, Cl)2.When creating an artificial dye, soda, coke and pitch are added.
Sulfur anions, which occupy certain positions in the crystal lattice of a substance, are responsible for the bright blue color of ultramarine.Pyrite impurities in the mineral give the dye a dark and dirty shade, the color of the marble becomes more turbid.
In artificial production, the range of ultramarine colors is wider. Light purple shade and resistant pigment is obtained when roasting at a temperature of 250 degrees. He also has a high hiding power. Strong violet comes out if the usual blue ultramarine is mixed with ammonium chloride and heated to 200 degrees.
Green color gives the dye a mixture of quartz and kaolin with sulfur, sodium sulphate and charcoal. The red pigment is obtained from violet using hydrochloric acid and air oxidation. In a similar way, you can create a pink hue.
The pigment is made in two stages. At the first stage, at high temperatures (first 450, and then 800 degrees) green ultramarine is obtained. Then it is amenable to re-firing at 450 degrees with access to oxygen. After that, excess sulfur is removed.
Ultramarine is used for tinting plastics, paper, paints and textiles. It is needed for dyeing rubber, linoleum. For these purposes, suitable pigment of various shades.But for painting they use mostly blue or purple ultramarine, red and yellow are unsuitable for this.