The coloring compounds
Colorings are an important ingredient in oil painting technology.
Colored, dry matter particles are called pigments, or organic (inorganic) carbon, or inorganic, often without very weak permeability or permeability on material surfaces. that they come into contact with. So adhesive is needed to hold them on those surfaces (on paper, canvas, wood, etc.). They are not dissolved in adhesives, but will be dispersed suspended in adhesives. Some colored beans have a source in nature (for example umber and sienna are soil). Other particles are manufactured (eg cadmium colors).
It is necessary to distinguish color grains from dyes. The dye is soluble and permeable. Chemical dyes can be turned into pigments, which separates them from solvents and then brakes them with a colorless inorganic substance (usually metal salts such as barium sulfate, calcium sulfate, aliminium hydroxide, aluminum oxide) so that they do not dissolve. These colored particles are called lakes. For example:
– Indigo (indigo) lake was made in ancient Egypt from the conifer leaf (woad), then imported from India;
– Hong madder lake is taken from the herb (madder). The synthetic color (synthetic) is called Azarin crimson;
– Carmine lake is extracted from dried mealybug carcass (yen chi) (available in tropical, subtropical countries, in South America and Mexico)
The color particles made from dyes often fade.
Organic seeds (organic) are usually mild, clear, high staining (high
tinting strength). Inorganic pigments are usually metallic, opaque compounds
(opaque), heavy, and dense (like cobalt, iron, zinc, …).
– Natural inorganic pigments such as ocher, umber, sienna are present in the soil colored by iron oxide, hydroxides, combined with clay, chalk, and silica.
– The inorganic pigment synthesized in industry is usually metal. There are also synthetic inorganic pigments that replace natural colors such as red mars and yellow mars.
– Organic colored seeds in nature are often extracted from herbs or animals (celestial, ivory, bones, vines)
– Synthetic organic colorants are carbon containing compounds such as quinacridone (red – purple)
The color particles are analyzed according to:
– tinting strength: Tested by mixing color with white in proportion 1:10. Organic pigments, especially synthetic ones, usually have a higher degree of staining than inorganic pigments;
– turbidity – clear: Some organic pigments are completely transparent due to their molecular structure, thus being used as a smooth color;
– light fastness: Some solid colors are strong when drawing solid, but not durable when paint is thin;
– speed of drying: VermiNion (red lipstick, red sand, mercury sulfide HgS) when mixed with oil makes oil dry slower, while cobalt makes oil dry faster.
– Oil absorption: Some colors need more oil. The more oil, the easier it is to crack.
b) Characteristics of oil paint color:
Depends on the manufacturer. So read the instructions on each color tube. Some famous brands: Lefranc & Bourgeois (1720) , Winsor & Newton (1832) , Talens (1899) , Holbein (1900) , Kusakabe (1996), Matsuda.
– Lead white [lead carbonate PbCO3: is the oldest white type, very poisonous, high coverage (opaque), warm colors, and many gradients, dry fast, but black (dead, dirty) over time. Because of toxicity, white lead is rare today, often sold only to painters in small tubes.
– Silvery white: [flake white or Cremnitz white]: lead carbonate + lead hydrate 2PbCO3 • Pb (OH) 2, get black when you have sulfur or smoke. The name “flake white” is derived from the production of lead white particles (See below). Kremnitz or Cremnitz is a place on the Hungarian-Slovakia border where lead mines are located, and Krems is a place in Austria where people make lead carbonate.
– White zinc (zinc oxide ZnO): weak coverage (semi-opaque semi-opaque), not used for drawing, but good for drawing in, or near-air. Pure white zinc is cold, long dry, when dry forms brittle film so it is easy to crack if drawing thick.