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What Is the Difference Between Phthalo Blue and Prussian Blue? (Explained)

What Is the Difference Between Phthalo Blue and Prussian Blue? (Explained)

Phthalo blue (also known as Thalo blue) refers to paintings that include the pigment Phthalocyanine Blue (PB15). Many watercolor painters have long favored this blue, and it appears to be a popular choice for a watercolor palette.

Each watercolor company creates a variety of Phthalo blue colors, which are usually classified by whether they have a green or red undertone. They’re usually called Phthalo Blue Red Shade (RS) or Phthalo Blue Green Shade (PGS) (GS).

Prussian Blue has a lot of “wow factor” since it was very sensitive to the alkaline environment of wet acrylic paint and hence extremely unstable. Phthalo Blue was included as the standard dark Blue color in all acrylic ranges in the early days of acrylics.

The history of Prussian Blue is lengthy and famous. It was the first synthetic pigment of the modern period. In the ancient world, Egyptian Blue was a similar but weaker color, but production ceased at the end of the Roman Empire, and the recipe for making it was lost.

Phthalo Blue and Prussian Blue
Phthalo Blue and Prussian Blue

Phthalo Blue

Phthalo blue is a color you’ve probably seen a million times but never given a name to — it’s the color of the sea, the sky, and, in the case of Bob Ross, snowy accents in paintings. Artists have been searching for the “perfect blue” throughout history, looking for a shade that captured colors seen – but not available – in nature, such as the color of the ocean.

Phthalo blue, a popular choice among today’s artists, was a viable option. Phthalo blue is an organic blue that has been marketed as “monastral blue” by chemists.

In November 1935, the hue was introduced as a pigment in London. It was hailed as the most significant blue discovery since Prussian blue in 1704 and artificial ultramarine in 1824, with some claiming it to be a superior pigment to both.

Phthalo Blue
Phthalo Blue

Prussian Blue

Matisse Prussian Blue is a color with a lot of “wow factor.” Because Prussian Blue was particularly sensitive to the alkaline environment of wet acrylic paint and thus exceedingly unstable, all acrylic ranges in the early days of acrylics included Phthalo Blue as the standard dark Blue hue.

Prussian Blue was an industry standard, but no development work had been done on the color in almost a century, and that didn’t matter to those who created it because it was still selling well. Prussian Blue began to show its age in the new century. The old color was no longer acceptable for a growing number of applications, and output was declining.

To save the industry, chemists began inventing new color variants that could endure the harsh conditions seen in modern polymers and paints. These new varieties were of exceptional quality and lacked none of the flaws that plagued previous generations of Prussian Blue.

painting
Painting

History

Matisse experimented with new color variants for a long time, and Matisse’s Prussian Blue is the product of his extensive experimentation.

Prussian Blue has a lot of benefits as a dark blue color on the palette, and it has a color that shines in the crystal transparent acrylic medium rather than the more greenish shade it has in oil. It has a new lease on life and even thrives after 200 years.

Prussian Blue has a long and illustrious history. It was the modern era’s first synthetic pigment. Egyptian Blue was a similar but weaker color in the ancient world, but production halted at the end of the Roman Empire, and the recipe for making it was lost.

There was a demand for a low-cost dark blue pigment, and in 1706, Johann Jacob Diesbach, a German paint and dye manufacturer, succeeded where centuries of alchemists had failed. He most likely synthesized for the first time and generated a lovely dark blue with excellent lightfastness that was also inexpensive to produce.

It generated a stir and was instantly dubbed Berlin or Prussian Blue after the city where it was created. Prussian, particularly Blue, was popular enough to spread to the Orient, and the gorgeous dark blue that we commonly associate with Japanese prints was Prussian.

Prussian Blue varies from Phthalo Blue in that it’s a denser mineral hue with more body when painting, and it’s not as greenish. As a general guideline, Phthalo blue should be used where more translucent glazing and watercolor effects are required, and Prussian Blue should be used where more opaque paint is required.

Difference Between Phthalo Blue and Prussian Blue

In acrylics, Phthalo Blue was the only choice for many years because the early versions of Prussian Blue became unstable in acrylic emulsions. However, advances in the technology of Prussian Blue manufacture have made that pigment both reliable to the quality, stable, and therefore viable in acrylic, and the two colors are very complementary.

Prussian Blue has more opacity and isn’t quite so greenish, so each pigment has advantages over the other in various circumstances. Phthalo Blue’s excellent transparency and cleanness of color give the stain a jewel-like quality. It’s the perfect blue for depicting blue and green color glass and for water and other transparent or translucent substances.

Difference
Prussian bluePrussian blue is, like a compound, Ferric hexacyanoferrate.
Phthalo bluePhthalo blue is a copper-phthalocyanine compound that I can’t decisively find a name for. They’re chemically very different from pigments.
Prussian bluePrussian blue is SUPPOSED to be darker, less saturated, and bright
Difference

In the ideal world, if something is called a name, it’s chemically precisely what that name entails down to the shade.
In reality, it depends on the manufacturer. If you buy paints, I advise getting paint chips if you can, because names tell you nothing about the color.

The Blues I Use: Phthalo Ultramarine Prussian Cobalt Cerulean

One company’s phthalo blue can be:

  • Darker
  • Lighter
  • Less or more saturated than another’s

The color on the container sometimes isn’t helpful, either. In manufactured paints, the difference can be null and void because they’re considered synonyms for some odd reason, or it can be night and day.

Final Thoughts

  • Paintings with the pigment Phthalocyanine Blue (also known as Thalo blue) are referred to as Phthalo blue (also known as Thalo blue) (PB15).
  • This blue has long been a favorite of watercolor painters, and it appears to be a standard option for a watercolor palette.
  • Prussian Blue was an industry standard, but there had been no development work on the color in nearly a century, and that didn’t bother those who made it because it was still selling well. In the new century, Prussian Blue began to show its age.
  • The old color was becoming unsuitable for a rising number of applications, and productivity was dwindling.

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