Five generations of chemists in the Blockx family have been working since 1865 to perfect the Blockx Oil Colors. Today they are still ground on stone rollers and mixed with poppyseed or linseed oil, and no additives or fillers whatsoever.
Color Swatch created using heavy application/medium application/50% tint and was applied on acrylic primed canvas (7 oz) material.
cobalt potassium nitrite
K3[Co(NO2)6] • H2O or CoK3N6O12
Cobalt Yellow is an expensive, transparent, very pure yellow with only fair hiding power. It is reliable in watercolor and makes particularly good tints. However, it must be carefully manufactured in oil form, or it can brown. Cobalt Yellow is known for good mixing quality with all other pigments, and it is useful in glazes and for tinting.
Cobalt Yellow has good permanence and lightfastness, and it can withstand strong sunlight.
Cobalt Yellow is highly toxic by inhalation or ingestion. The ingestion of this pigment has caused cyanosis (low oxygen levels in the blood) due to methemoglobinemia.
Cobalt comes from the Middle High German word kobolt, an underground goblin, because miners thought cobalt harmed silver ores. The discovery of the potassium and cobalt compound used to make Cobalt Yellow is credited to N.W. Fischer in Breslau in 1848. It was not introduced as an artists’ pigment until 4 years later, by Saint-Evre in Paris. During the previous century, it was considered the only color that could reasonably replace Indian Yellow.
Cr2O3 • 2 H2O or Cr2(OH3)
Viridian is the standard green and is stable, powerful, and cold with an emerald green undertone. It has a transparent hue, good tinting strength, a dark masstone that can be almost black at full strength, and a slow drying time in oil form. Viridian is commonly replaced by the darker, more saturated, and staining Phthalo Greens, but its properties make it a necessary part of the palette of an experienced landscape painter.
Viridian has excellent permanence, except in high-temperature work, and is highly valued as a glazing color.
Viridian is slightly toxic.
Viridian’s name comes from the Latin viridis, meaning green. The process for manufacturing Viridian, or Transparent Oxide of Chromium, was patented by Guignet in Paris in 1859. However, it had actually been discovered by Pannetier and Binet in 1838. Viridian replaced Verdigris, which was reactive and unstable, and Emerald Green, which was a poisonous copper aceto-arsenite used as a rat poison in the sewers of Paris.
Emerald Chromium Oxide, Emeraude Green, French Veronese Green, Guignet’s Green, Pannetier's Green, Permanent Green, Smaragd Green, Transparent Oxide of Chromium, Vert Emeraude. Casali's Green and Mittler's Green are varieties of Viridian. Viridian has historically been sold under the name Emerald Green, but they are currently considered to be and are marketed as two different pigments.
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