Prussian Blue was discovered by accident in 1704. According to the most widely accepted account, a Berlin pigment maker named Johann Jacob Diesbach was trying to make a red pigment when he unknowingly used potash contaminated with animal blood. Instead of red, the mixture produced a deep blue colour.
The contamination came from the pharmacist Johann Konrad Dippel, who realized what had happened and saw the commercial potential of the new pigment. Together, he and Diesbach refined the process and sold the colour as Berlin Blue. The formula remained secret until 1724, when it was reverse-engineered and published by an English chemist.
Despite its strange beginnings, Prussian Blue was a major breakthrough. It was the first synthetic blue pigment since ancient Egyptian Blue, and it transformed painting. No comparable blue pigments appeared for over a century, until the development of Cobalt Blue and synthetic Ultramarine.
Why Does Pigment PB27 Rarely Appear in Acrylic Ranges?
Prussian Blue (PB27) is common in oil and watercolour ranges and is widely used in relief printmaking inks, reflecting its historic role in woodblock printing. However, genuine Prussian Blue is notably rare in acrylic paint ranges.
This is due to the pigment’s sensitivity to alkaline environments. Prussian Blue requires a binder with a pH of 7 or lower. Both linseed oil and gum arabic—the binders used in oil and watercolour paints—are mildly acidic. Acrylic polymer emulsion, by contrast, is alkaline, which can destabilize the pigment.
As a result, most acrylic manufacturers recreate the colour using mixtures of more stable pigments.
How Permanent Is Prussian Blue?
Although Prussian Blue works well in oil and watercolour, it has a mixed reputation. Early on, artists noticed that it could fade over time, especially when exposed to strong light or mixed with alkaline pigments.
Because manufacturing quality varied, its reliability was inconsistent. When Phthalo Blue became available in the mid-20th century, many artists switched to it because it offered similar strength and range but much better lightfastness. Phthalo Blue is brighter and more intense, while Prussian Blue remains darker and more subdued.
Modern production has improved the stability of Prussian Blue, but its permanence can still vary. While manufacturers often rate it as highly lightfast, real-world results don’t always match lab testing.
One unusual feature is that Prussian Blue can regain its colour after being kept in dark, well-ventilated conditions. Because of this, some museums rotate artworks containing Prussian Blue to help preserve them.
Colour Mixing with Prussian Blue
Prussian Blue is an exceptional mixing colour. When combined with Lemon Yellow, it produces intensely bright, almost fluorescent greens—unnatural, vivid hues reminiscent of artificial light. When paired with Nickel Azo Yellow, it yields a range of deep, muted greens well suited to landscape painting.
Its pronounced green undertone also makes it a compelling partner for reds. Mixed with Indian Red, Prussian Blue creates a rich chromatic black—ideal for artists who prefer to avoid true black pigments while retaining depth and complexity.
These mixtures highlight Prussian Blue’s versatility and expressive range. Despite its challenges, it remains one of the most characterful pigments available.
How do you use Prussian Blue in your own work?
