Schmincke Soft Pastel - Prussian Blue 066D

Pigment Information

This color contains the following pigments:

PB27-Prussian Blue

PB66-Indigo

PB29-Ultramarine [Blue]

Pigment Name

PB27-Prussian Blue

Pigment Type

inorganic

Chemical Name

ferric ferrocyanide/iron(III)-hexacyanoferrate(II)

Chemical Formula

Fe7(CN)18(H2O)x or C6FeN6H4N

Properties

Prussian Blue is a semi-transparent, deep cyan-blue with a greenish undertone and a very high tinting strength unequaled by most pigments. It is similar to Phthalo Blue unless mixed with white, when it gives up intensity and becomes smoky. It can behave erratically and less reliably in oil and watercolor form depending on its manufacture. For permanent painting Phthalo Blue is considered a more reliable choice.

Permanence

Prussian Blue is lightfast and permanent in all techniques except for fresco. When mixed with Zinc White in watercolor or tempera form, it fades upon exposure to light and completely regains its chromatic strength in the dark. Modern manufacturing techniques have made this tendency less of an issue in recent years

Toxicity

Prussian Blue is moderately toxic if ingested. It will emit toxic hydrogen cyanide gas if heated, exposed to ultraviolet radiation, or treated with acid.

History

"The first of the modern pigments," Prussian Blue is the first artificial pigment with a known history. It was discovered by accident in 1704 by the Berlin color maker Heinrich Diesbach, who was trying to create a pigment with a red hue by mixing iron sulfate and potash. The potash Diesbach purchased from a local laboratory had been contaminated by animal oil and blood during previous experimentation. The resulting mixture yielded a very pale red that changed to purple and then deep blue when he tried to concentrate it. Since previous blue pigments came from lapis lazuli, an expensive stone, Diesbach’s discovery was extremely important for artists of the time.

Pigment Name

PB66-Indigo

Pigment Type

synthetic, organic

Chemical Name

2,2’-Bis(2,3-dihydro-3- oxoindolyliden)

Chemical Formula

C16H10N2O2

Properties

Indigo is a deep blue pigment, almost violet dye that can be laked as a pigment.

Permanence

Indigo is fugitive. Indigoid Blue is the famous blue dye used in many blue jeans and other denim products, famous for the way it fades! Although a few paint manufacturers offer a genuine indigo color based on PB66, it should be used only for applications that are not permanent, or where the color is required for historic reasons. Most paint manufacturers replicate this historic hue with other more permanent pigments.

Toxicity

Although natural indigo is known to be mildly toxic, its toxicity is believed to be the result of other natural alkoids found in plant sources, not of the indigo dye itself. The acute and chronic toxicity of synthetic indigo dyes has been studied and has

History

Indigoid Blue is a synthetic version of Indigo, a famous dye and laked pigment that has been used since ancient times. The chemical compound that constitutes the indigo dye is called indigotin. More than 30 species of plants, found in many parts of the world, can be used to produce indigo dye. Indigo dye became the rage in Europe during the late Middle Ages. Although genuine indigo from plant sources is available, only the synthetic version is now used in commercial dye and pigment products. Genuine Indigo is designated NB1 (Natural Blue 1). The synthetic dye molecule was first synthesized by Bäyer in 1878, and it later became available as a commercial dye, quickly replacing natural sources.

Pigment Name

PB29-Ultramarine [Blue]

Pigment Type

inorganic

Chemical Name

complex silicate of sodium and aluminum with sulfur

Chemical Formula

Na8-10Al6Si6O24S2-4 or Na6-8Al6Si6O24S2-4

Properties

Ultramarine is the standard warm blue, a brilliant blue pigment that has the most purple and least green in its undertone. It has a moderate to high tinting strength and a beautiful transparency. Synthetic Ultramarine is not as vivid a blue as natural Ultramarine. Ultramarine dries slowly in oil and tends to produce clean, though granular, washes in watercolor. French Ultramarine mixes well with Alizarin colors in oil and watercolor form to create a range of purples and violets. It can dull when mixed with white in acrylic form, but mixes well with other colors. The shade varies based on manufacturer. Considered a great color for glazes, it is not suitable for frescoing.

Permanence

Ultramarine has excellent permanence, although synthetic Ultramarine is not as permanent as natural Ultramarine. It may discolor if exposed to acid because of its sulfuric content.

Toxicity

Ultramarine has no significant hazards.

History

The name for this pigment comes from the Middle Latin ultra, meaning beyond, and mare, meaning sea, because it was imported from Asia to Europe by sea. It is a prominent component of lapis lazuli and was used on Asian temples starting in the 6th century. It was one of the most expensive pigments in 16th century Europe, worth twice its weight in gold, and so was used sparingly and when commissions were larger. Ultramarine is currently imitated by a process invented in France in 1826 by Jean Baptiste Guimet, making blue affordable to artists and extending the range of colors on their palettes.