Manganese violet
Composition and Properties of Manganese Violet
Manganese violet is ammonium manganese-(III) pyrophosphate with the formula of MnNH4P2O7. The pigment is destroyed by strong acids and alkalis. It is resistant to heat up to 250 °C and has excellent stability to light.
Names
Nuernberg violetPV 16, CI 77742As the name of a black mineral, oxide of manganese (used from ancient times in glassmaking for removing coloring matter), from French manganèse, from Italian manganese, alteration or corruption of Medieval Latin magnesia.From Online Etymology Dictionary
Preparation
The pigment can be prepared by heating a mixture of manganese oxide, phosphoric acid, and ammonium dihydrogen phosphate at 120 °C for 4 hours and subsequently at 300 °C for a further 1 hour. Finally, water is added to the hot reaction mixture and it is boiled for a further 4 hours. The resulting product is then washed and dried (1).
History of Use
The pigment was discovered in 1868 but was not used frequently in oil painting due to its low tinting strength.
