Prussian Blue is a deep, moody blue valued for its strength, staining power, and ability to create luminous darks. It is especially prized by watercolor artists for producing transparent near-blacks and dramatic shadow mixtures without the deadening effect of tube blacks.
Understanding Prussian Blue on the Palette
Prussian Blue sits on the cool blue side of the color wheel and leans slightly toward green, though it is more neutralized than high-chroma blues such as Winsor Blue. This subtle neutrality gives it tremendous versatility, particularly in shadow work and dark passages.
Because it is semi-transparent and staining, Prussian Blue excels in layered washes and deep value building. It is not a delicate blue; instead, it is a workhorse pigment used for structure, depth, and atmosphere.
Pigment Information: What Prussian Blue Is Made Of
Prussian Blue is made from Iron Blue (PB27), one of the earliest synthetic pigments.
Typical characteristics include:
- Semi-transparent
- Strong staining behavior
- High tinting strength
- Minimal granulation
- Excellent depth at low dilution
PB27 is known for its ability to create very dark values while remaining transparent, a rare and valuable quality in watercolor.
Handling & Mixing Characteristics
Prussian Blue is known for:
- Rapid value buildup
- Strong staining of paper fibers
- Smooth, even washes
Because of its staining strength:
- It is difficult to lift once dry
- It should be used with a light hand
- Small amounts significantly affect mixtures
It mixes especially well with reds and greens to produce rich, neutral darks.
Why Prussian Blue Works Well in Color Theory Systems
As a cool, dark blue, Prussian Blue:
- Creates strong value contrast
- Produces transparent neutrals instead of flat blacks
- Supports sophisticated shadow mixtures
Its neutrality allows it to function as a darkening agent without overwhelming color relationships.
Use Prussian Blue for Dark Backgrounds
Prussian Blue is similar to Winsor Blue, but it is a neutralized semi-transparent staining watercolor. I mix Prussian Blue with Alizarin Crimson and Viridian to create strong darks for backgrounds and to darken other colors.
This dark mixture is almost black, but is still transparent. I use it instead of black tube paints such as Ivory Black, Neutral Tint, Payne’s Gray, etc. which have an undesirable flat appearance.
Color Schemes Using Prussian Blue
Prussian Blue’s complement on the traditional color wheel is a shade of red-orange, but in watercolor, artists often use warm reds and burnt sienna to neutralize it or create rich, earthy browns and grays, with orange/gold offering vibrant contrast and reds/browns creating sophisticated shadows.
Key Complementary Colors & Uses:
- Cadmium Scarlet: Painting Prussian Blue adjacent to a vibrant red-orange, creates an energetic contrast, making the blue pop.
- Light Red / Burnt Sienna: Mixing Prussian Blue with reds/browns creates beautiful, deep, cool grays and muted browns, perfect for shadows or stormy skies.
- New Gamboge / Cadmium Yellow: Mixing Prussian Blue with warm yellows creates olive greens, while cooler yellows make brighter greens, though these are analogous, not complementary.
Why This Matters for Watercolor:
- Neutralizing: Adding a touch of its complement (like Cadmium Scarlet or Light Red) to Prussian Blue cools it down and dulls its intensity, making sophisticated grays.
- Shadows: Mixing Prussian Blue with its reddish or brownish complement creates realistic, rich shadow colors, as pure blue shadows can look flat.
Prussian Blue Compared to Other Blues
- Prussian Blue: deep, staining, neutralized
- Winsor Blue (Green Shade): high-chroma, very cool, intense
- French Ultramarine: warm, granulating, non-staining
Prussian Blue excels where depth and darkness are needed without sacrificing transparency.
Best Uses for Prussian Blue
Prussian Blue is particularly effective for:
- Dark backgrounds
- Night scenes and stormy skies
- Deep water passages
- Shadow construction
- Neutral dark mixing without black
Limitations of Prussian Blue
Despite its strengths, Prussian Blue:
- Can easily overpower mixtures
- Is difficult to lift due to staining
- Can appear heavy if overused
It benefits from dilution, restraint, and thoughtful pairing with warmer pigments.
A Note on Prussian Blue’s Role on the Palette
Prussian Blue is a structural, atmospheric color rather than a decorative one. Its ability to produce transparent, luminous darks makes it indispensable for artists who want depth and realism without relying on premixed blacks. Used intentionally, it adds sophistication, drama, and control to watercolor palettes.