Prussian blue

Berlin blue was offered under many different names. The designations refer to the names of the inventors or manufacturers, the places of manufacture, the color shades, the applications or the chemical components and processes. The varieties may differ in color cast. All names refer to blue pigments based on the Fe(II)/Fe(III) cyano complex and differ only slightly in composition. The type and amount of alkali metal or ammonium ions used influences the production of certain color shades. Historically, the pigment was marketed as blue salt. In the Colour Index, Berliner Blau is listed as C.I. Pigment Blue 27 by colour and by structure as C. I. 77510 for potassium-doped iron blue and C.I. 77520 for ammonium-sodium iron blue, respectively.

Diesbach blue is named after the actual inventor. Turnbull's blue was developed in 1828 by John Turnbull Jr. and distributed through the Scottish company Turnbull & Ramsay in Glasgow. Turnbull's blue is a blue pigment formed from red blood liquor salt with excess iron(II) ions. It is obtained by reacting ferrous salts with potassium hexacyanidoferrate(III) in aqueous solution. Initially, it was assumed that the dark blue precipitate formed had a different composition from the Berlin blue obtained by reacting ferric salts with potassium hexacyanidoferrate(II) (yellow blood leach salt). However, by means of EPR and Mößbauer spectroscopy, it was found that the reaction products are largely identical, since the following equilibrium exists:

Milori blue refers to cooked varieties of the pigment, which have a somewhat warmer reddish hue and were first produced by the Milori de France company. According to Diesbach, this company had obtained a blue pigment by a different process, which is somewhat weaker in color strength compared to Prussian blue. The name Milori blue has survived to the present day. Vossenblau was named after L. Vossen & Co G.m.b.H. near Düsseldorf, which was the exclusive distributor from 1905.

French blue or Paris blue refers to the company headquarters of A. Milori. Prussian blue, also Prussian blue, as well as Zwickau blue also refer to production locations.

The name bronze blue refers to the bronzing red tint that is evident in various binders. In particular, bronze blue refers to the reddish sheen of the unground, black-blue lumps.

Chinese Blue or China Blue takes its name from decorative porcelain. This production variant of the pigment produces the purest and most brilliant shades with a green tint. It gives the best full tone and the highest opacity, however it has the hardest texture and the highest oil requirement. Saxon blue refers to the color of the uniforms of the Saxon army, which were dyed with Berlin blue. Toner blue or ink blue got this name because of its use to tint the reddish (brown) tint of carbon black.

The names iron blue, iron cyanogen blue, iron hexacyanidoferrate, steel blue, iron cyanogen cyanide, ferrocyanogen blue and ferriferrocyanide blue as well as steel blue are derived from the structure or composition of the pigment. Potash blue refers to the use of potash in its manufacture. Until World War I, the cation of the complex salt was predominantly potassium. When the price of potash rose sharply in the early 20th century, the ammonium salt was produced with equally good properties. Iron blue also refers to an ancient pigment from the mineral vivianite.

Luisenblau, Modeblau, Wasserblau are product names for modified colorants in textile dyeing and may have originated as names for fashion dyes. The reddest pigment is Milori blue, the greenest variant is Chinese blue.

In the Frenchlanguage area the designations Bleu de prusse or Bleu de Milori are common, in the English language area the designations iron blue, toning blue or Prussian blue.

Berlin blue is considered to be the first modern pigment that does not occur naturally in this form. One of the main components, potassium hexacyanidoferrate(II), on the other hand, occurs as the rare mineral kafehydrocyanite.