PB27

Prussian Blue or Milori Blue. We associate this pigment with a sort of crisp Sea Captain one moment and a drunken sailor the next-- a sort of pigment with many faces. It's a color with a strange backstory, as its discovery involved blood. This is a moody, dark, transparent indigo that lends itself to marine landscapes as well as any darkened middle-to-low-chroma color in the blues.

Prussian Blue's peculiar lightfastness behaviors have been the subject of commentary for over a hundred years. Here we need to relay a big heads-up because this pigment may be listed as ASTM I (meaning excellent) for lightfastness on the back of paint tubes, but that is potentially unintentionally misleading. It may have some strange behavior depending on the mixing white used in oils. Golden's recent lightfastness testing explores some of the issues.

One of the many strange quirks of this color is that some versions can show bronzing where it develops a sheen in masstone. Of the many ways to prepare this color, some yield more bronzing than others, and unfortunately these methods of preparation and variations in quality are not adequately differentiated by the name nor the pigment code. Some older books will ascribe different names to different versions, but unfortunately paint naming is currently a wild west situation, and paint names can't be sufficiently relied upon. Prussian Blue has a lot of related color names which fly under the flag of PB27 such as Antwerp Blue or Paris Blue.

Unfortunately its lightfastness isn't what was once thought, as Prussian Blue is fairly sensitive to the mixing white involved. It's interesting that this was ever listed as ASTM I as certain pigment suppliers now list its performance in tints to be quite low (as low as blue wool scale 2)! The choice of mixing white also matters, and it has displayed some unexpected lightfastness in Lead White, PW1.

One of Prussian Blue's many faces is a creepy one. It is sort of a Nosferatu where in some media it can fade a bit in light, but is said to regain some of its color again when set in the dark. We've never personally noticed this, but we have heard this in reports.

This pigment requires a fairly high amount of oil and yet it is a fast drier. We've heard tales of the paint alligatoring -- where a blob wrinkles up as the paint dries.

Prussian Blue is generally thought of as not really toxic, but we were surprised to hear of unexpected hazards. For toxicity please consult Monona Rossol's work available via her site.