PV23—Dioxazine Violet

Pigment Type

organic

Chemical Name

carbazole dioxazine

Chemical Formula

C₃₄H₂₂Cl₂N₄O₂

Properties

Dioxazine Violet is transparent and has very high tinting strength. It is a staining pigment, very dark valued when it is used at full strength. Concentrated, it paints out nearly black, but it mixes with Titanium White to form bright, opaque tints of purple. PV23 produces slightly redder shades than PV37. Because the hue can vary with the conditions of preparation and grinding, it may be offered in red shade, blue shade, and so forth.

Permanence

Dioxazine Violet has good lightfastness. There may be some concern about it fading or shifting in color in tints and washes. Some artists have reported that PV37, a molecular variant, is more lightfast than PV23.

Toxicity

n/a

History

Two molecular variants of Dioxazine Violet, PV23 and PV37, are available. They have similar properties, but mix slightly differently.

Alternate Names

Dioxazine Purple, Chromothal Violet, Mauve, Carbazole Violet.

PR122—Quinacridone Magenta

Pigment Type

organic, quinacridone

Chemical Name

n/a

Chemical Formula

C₂₂H₁₆N₂O₂

Properties

Quinacridone Magenta is a semi-transparent and powerful bluish red with an impressive mixing range. It makes an excellent glazing color and is one of the bluest of the Quinacridone colors. The pigment's properties vary considerably, depending on how it is ground. Quinacridone pigments have relatively low tinting strength in general. For this reason, quinacridone colors are often expensive, because more pigment is required in the formulation.

Permanence

Quinacridone Magenta offers very good lightfastness in most media, but some have argued that it is less lightfast in watercolor form. Although Quinacridone Magenta received only a passing grade of "fair" under ASTM test protocols, other test results have rated the pigment very good to excellent. Transparent reddish violet pigments in general have more problems with lightfastness than any other range of colors. PR122 is often used as the Magenta of CMYK (four color) process printing because it offers a better tradeoff between tinting strength and lightfastness than other pigments in its class.

Toxicity

Quinacridone Magenta has no acute hazards. Overexposure to quinacridone pigments may cause skin irritation. Quinicridone pigments contain a compound found to be a skin, eye, and respiratory irritant.

History

Quinacridone Magenta came from a red violet aniline dye that was first produced in 1858 by Natanson. It was called Magenta to commemorate a battle in Magenta, Italy. Over time, Magenta became the standard color name for a deep, violet red. Although quinacridone compounds became known in the late 19th century, methods of manufacturing so as to make them practical for use as commercial pigments did not begin until the 1950s. PR122 has become particularly popular in the formulation of Magenta for CMYK process printing.

Alternate Names

Acra Red, Quinacridone Violet (PV19), Thalo Red Rose.

PB73—Cobalt Blue Deep

Pigment Type

inorganic

Chemical Name

cobalt silicate blue olivine

Chemical Formula

Properties

Cobalt silicate blue olivine is a transparent blue pigment with low tinting strength.

Permanence

Cobalt silicate blue olivine is permanent and lightfast. Its stability at high temperatures has made it a favorite in coloring glassware and ceramics.

Toxicity

Cobalt silicate blue olivine is mildly toxic and a respiratory irritant, but less toxic than some of the other cobalt salts used as pigments. In liquid form it is not considered hazardous.

History

Cobalt silicate blue olivine is a cobalt salt that is frequently used as a colorant in glass and ceramics. It has been used in natural mineral forms since ancient times. Techniques for manufacturing Cobalt Blue, a chemically pure salt of cobalt and aluminum oxide, were developed in 1802. Synthetic processes for other cobalt salts, including cobalt silicate blue olivine, were developed in the 19th century.

Alternate Names

Smalt Blue, Cobalt Silicate.