User:Elysewiese/Manganese violet

Manganese violet is a vibrant purple, inorganic pigment generated through a chemical reaction. The commercially available compound is composed of ammonium, manganese, and pyrophosphate. Manganese violet, naturally, is an impure pigment; therefore, oxide impurities cause variations in the pigment's color. Consequently, there has been controversy about the pigment's hue as it has been reported to be both a true violet hue and not a violet hue. Among the artistic community, manganese violet became popular among certain artists. For example, Claude Monet used manganese violet in his Rouen Cathedral series to further his exploration of shadows. Beyond the artistic community, manganese violet has been used in cosmetics to color products like lipstick and eyeshadow.

History
Originally named Nurnberg violet, there is little known about manganese violet's history beyond its creation in 1866 by E. Leykeuf. The first documented production of the pigment was in 1890 by Messers Winsor and Newton (currently known as Winsor & Newton). Throughout color manufacturing history, the manganese violet pigment was described in different manners. In the Winsor & Newton 1982 catalog, both permanent violet and permanent mauve were listed. The two were distinguished by the company in 1986 when permanent mauve was described as phosphate of Manganese (which is another name for manganese violet). In the 1898 Reeves list, permanent violet and permanent mauve were listed as the same color. The differing descriptions of the pigment could be the result of the debate surrounding manganese violet's true hue.

Chemical Characteristics
Manganese violet's chemical formula is. The compound is generated through reacting manganese dioxide, phosphoric acid, and ammonium dihydrogenphosphate. Manganese violet's chemical reactions begins with the production of a compound by combining manganese dioxide and phosphoric acid. After this, the synthesized mass is heated with the ammonium compound, which precipitates manganese hydroxide. Next, this compound is heated in water to produce an insoluble precipitate. After cooling, filtration, and drying, the remaining compound is manganese violet. By various accounts, the pigment is reported as toxic when inhaled.

The compound is soluble in hydrochloric acid, but insoluble in water; therefore, the pigment is stable in low pH conditions, but its stability deteriorates with rising pH. Furthermore, the compound can be decomposed by lyes, producing manganese oxide as the byproduct. The manganese violet pigment remains stable under high heat conditions. The commercially available pigment has two identifiable polymorphs: α- and β-forms. While the polymorphs of manganese violet differs slightly, both α- and β-forms are stable at high temperatures. The optical properties of manganese violet arise from the distorted octahedral sites of the α- and β-forms. The infrared spectroscopy, reflectance spectrum, and fluorescence spectroscopy can be found on ColourLex.

Pigment Characteristics
Manganese violet is reported as a fine, vibrant purple pigment that is synthetically generated. Additionally, the pigment is believed to have exceptional permanence; therefore, the quality of the pigment does not change over time. Manganese violet also has high lightfastness and, hence, the pigment resists color change over exposure to light.

Visual Characteristics
When the pigment is used as a paint, there have been reports that artists tended to shy away from manganese violet because of its dullness. Variances in visual characteristics arises from the pigment's impurities because traces of foreign oxides causes the hue of the pigment to change. Consequently, the visual characteristics of manganese violet remains a great source of contention among the artistic community. Some sources claim that manganese violet is actually a more accurate violet hue than previous pigments like cobalt violet. This is because cobalt violet has a redder tone than manganese violet. Conversely, some sources assert that manganese violet (as well as cobalt violet) should not be categorized as violet according to modern color measurements. By example, manganese violet was reported to have being used in Édouard Manet's The Waitress; however, in this painting, manganese violet was used to create the red or purple colors seen in the painting. Hence, these sources argue that manganese violet should not be classified as violet because neither the scientific evidence nor historical usage of the pigment signifies a violet color.

Artistic Use
The manganese violet pigment is compatible with many artistic techniques; however, there are a few techniques like fresco and stereochromy that are chemically incompatible with this pigment. The pigments' popularity was short lived within the artistic community because of its dullness and poor hiding power.

Beyond its technical use, manganese violet had an impact on the artistic community because it furthered the exploration of shadows. Claude Monet, by example, was an avid proponent of manganese violet's usage for shadows. Monet was quoted saying "I have finally discovered the true color of the atmosphere. It's violet. Fresh air is violet. Three years from now, everyone will work in violet." Following suit of the impressionism movement, violet replaced the usage of black pigments for shadowing because black was not found in nature. In Monet's Rouen Cathedral series, he utilized different colors to display how the perception of the same cathedral changes based on the lighting during different times of the day. In The Rouen, Cathedral, West Facade, Sunlight and The Portal of Rouen Cathedral in the Morning Light, Monet manipulated the shadows through using manganese violet and other pigments to represent different times of the day. Other artists like Georges Seurat also employed manganese violet within their paintings; however, the reasoning for using the pigment different. Instead of using manganese violet broadly within different paintings, Seurat only utilized the pigment when necessary. Seurat centralized his color palette around pure colors, which are colors that have a homogeneous light spectrum. By example, pure colors are cobalt blue, French ultramarine, and lead white. In contrast to pure pigments, manganese violet is not a pure color because of oxide impurities in the pigment; therefore, there can be variances in the color. For many of his works, Seurat would combine other pure pigments to create a violent hue and, consequently, he would only utilize impure pigments like manganese violet for specific purposes. In Seurat's painting Channel of Gravelines, Grand Fort-Philippe, by example, manganese violet was used in the border. There is speculation that Seurat utilized manganese violet in the border because of its low tinting power. In comparison to manganese violet, pure pigments and their mixtures have high tinting powers, which may have been undesirable in this case; therefore, Seurat opted to use manganese violet for this painting.

Cosmetic Use
Beyond the artistic community, manganese violet is used various cosmetics such as lipstick and eye products. By United States government standards, the pigment has been reported as a safe compound for coloration of products used around the eyes. In eyeshadow, for example, manganese violet can be used to produce pleasant violet shades. Additionally, the pigment is often used in lipstick to counter brighter pigments. Yet, in recent years, scientific journals have raised concerns about manganese violet's use (among other metal pigments) in cosmetics. In lipstick, by example, researchers are worried about poisoning through ingestion of metal pigments like manganese violet because of their toxicity.