Yellow Ocher Light Dispersion

Yellow Ocher Light is from the ocher deposits in the French quarries of Gargas and Rustrel, nestled in a 12-mile-long enclave in the heart of the Luberon Massif, the ocher country. Ocher is a symphony of colors ranging from pale yellow through the orange range to intense red. It has two major characteristics: it never fades in daylight, and the color is highly concentrated.

Rublev Colours Aqueous Dispersions are pigments dispersed in water ready to be mixed with water-based mediums. These dispersions are specially 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, pigment, and water, making them ideally suited for traditional mediums. Unlike other pigment dispersions 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.

Rublev Colours Yellow Ocher Light Dispersion

Origin and History

Known since antiquity, ocher (okhra, Greek) occurs naturally as yellow ocher (limonite) or as red ocher (hematite). Ocher has been used as a pigment since prehistoric times and is perhaps the most widely used pigment for artists' paints.

Source

Yellow ocher is a natural earth containing clay tinted by hydrous forms of iron oxide, such as goethite, and traces of gypsum or manganese carbonate. Historically, yellow ocher was designated by the mineral name limonite. Limonite is not a true mineral but a general term to describe all forms of hydrated iron oxide minerals (α-FeOOH) that occur as natural earth. Limonite includes the minerals goethite, akaganeite, and lepidocrocite. Iron oxide content must not be less than 12% to be considered an ocher, with varying amounts of kaolin and quartz. Depending upon the hydrated iron oxide's content, the ocher's color varies from light yellow to golden. Like red iron oxides (hematite), they are found worldwide and have been used as pigments since prehistory. French ocher, historically one of the best grades of ocher, contains about 20% iron oxide and is high in silica.

Ocher grades into sienna, a yellow-brown pigment containing more iron ore than ocher and some manganese dioxide. Sienna grades into umber, which is darker brown and contains a higher percentage of manganese dioxide. Burnt sienna is brown or bright red, and burnt umber is a darker brown than umber.

Ocher is not naturally usable as a pigment and, therefore, needs to undergo several critical processes, such as:

• Extract ore from the quarries.
• Separate ocher from sand using water and centripetal force.
• Blend different ocher extracted from diverse veins to obtain the selected colors.
• Grind to 50 microns and pack.

Permanence and Compatibility

Ocher is among the most permanent colors in the artist's palette. It is compatible with all other pigments and can be used with good results in all mediums.

Oil Absorption and Grinding

Ocher absorbs a moderately high amount of oil. The oil absorption ratio is 30–35 parts by weight of linseed oil to 100 parts by weight of pigment. If the measurement were grams, this pigment would require 30-35 grams of pigment to grind 100 grams of linseed oil to form a stiff paste. It slows the drying of oil paint but forms a good film.

Toxicity

Ocher is not considered toxic, but care should be taken when handling the dry powder pigment to avoid inhaling the dust.