Rublev Colours Aqueous Dispersions are pigments dispersed in water ready to be mixed with water-based mediums. These dispersions are especially made for use with traditional painting mediums, such as egg tempera, casein tempera, fresco, watercolors and distemper (glue tempera). They are also ideally suited for use with gesso to make toned grounds for drawing and painting. Pigment dispersions from Rublev Colours contain only naturally-derived ingredients, in addition to pigment and water, making them ideally suited for traditional mediums. Unlike other pigment dispersions that are typically made for acrylic medium, Rublev Colours Aqueous Dispersions do not contain coalescent solvents, artificial dispersing resins and other additives that interfere with natural mediums. Aqueous Dispersions make preparing traditional mediums easy; you do not have to hassle with powders, grinding pigments in medium and calculating binder ratios to make water-based paint. They make adding the right amount of paint binder, such as egg yolk, a no brainer because the right amount of water is already contained in the dispersion, simply add egg yolk.
| Color Names | |
| Common Names: | Dutch: ultramarijnblauw English: ultramarine blue French: bleu outremer German: Ultramarinblau Italian: blu oltremare Spanish: azul ultramarino |
| Alternate Names: | azure blue, azzurrum ultramarine, azzurrum transmarinum, azzuro oltramarino, azur d'Acre, Lazurstein, pierre d'azur |
Origin and History
In 1814, Tassaert observed the spontaneous formation of a blue compound, very similar to ultramarine, if not identical with it, in a lime kiln at St. Gobain, which caused the Societé pour l'Encouragement d'Industrie to offer, in 1824, a prize for the artificial production of the color. Processes tomake the artificial pigment were devised by Jean Baptiste Guimet (1826) and by Christian Gmelin (1828); but while Guimet kept his process a secret, Gmelin published his and thus became the founder of the "artificial ultramarine" industry.
Source
Ultramarine is a blue pigment consisting of a double silicate of aluminum and sodium with sulfide and occurring in nature as a component of lapis lazuli. The Colour Index designation is Pigment Blue 29 and Colour Index number is 77007. Ultramarine is one of the most complex mineral pigments, a sulfur-containing compound of sodium-silicate, essentially a mineralized limestone containing a blue cubic mineral called lazurite (the major component of lapis lazuli). The term ultramarine designates both the natural mineral and the artificial pigment, although today most distinguish the natural mineral by its name lazurite or the rock containing it, lapis lazuli.
Permanence and Compatibility
Ultramarine is a synthetic blue pigment that is rated by the American Society of Testing and Materials (ASTM International) as lightfastness category I, which is the highest lightfastness. It is compatible with all pigments, but is sensitive to acids, so avoid using it with acidic mediums and supports.
Oil Absorption and Grinding
Ultramarine blue absorb a medium amount of oil (38 to 42 grams per 100 grams of pigment), which may slow the drying of oil paint and hence is a moderate drying oil color. It is highly refractive pigment and is difficult to grind in oil, although it easily disperses in water.
Toxicity
Ultramarine blue is not considered toxic, but care should be used in handling the pigment.
Aqueous Pigment Dispersion: Ultramarine Blue (Greenish Shade)
| Pigment Information | |
| Color: | Blue |
| Colour Index: | Pigment Blue 29 (77007) |
| Chemical Name: | Sodium Sulfide Aluminosilicate |
| Chemical Formula: | Na2OSAl2O3SiO2 |
| ASTM Lightfastness Rating | |
| Acrylic: | I |
| Oil: | |
| Watercolor: | I |
| Properties | |
| Specific Gravity: | 2.35 |
| Oil Absorption: | 38-42 g oil / 100 g pigment |
| Median Particle Size: | 2-4 microns |