Art and Nature: The Alchemy of Blue (2 of 2)

In France, the manufacture of paint was controlled by the Academie de St. Luc (the Painters’ Guild of France).  In 1764, this guild seized a local factory making Prussian Blue, claiming that the production of the pigment was not authorized by them.  Then, the factory owners asked the Paris Academy of Sciences to determine the nature of Prussian Blue.  They stressed that they were manufacturing a chemical widely used by various groups such as textile manufactures as well as artists.  Was this synthetic pigment a paint or a chemical?  The French chemist Jean Hellot (1685 - 1715) determined that Prussian Blue was a product of chemistry and not art.  Therefore the painters’ guild had no control over its manufacture.  The factory was allowed to reopen, and to continue manufacture this synthetic pigment.

Because of its unique chemistry, Prussian Blue is used by art experts to detect earlier fakes.  The first painting to use this pigment is “Entombment of Christ” by Pieter van der Werff (Dutch, 1665-1722) in 1709.  (The sky and the Virgin Mary’s veil are Prussian Blue.)Through the use of searching for Prussian Blue in paintings, several fakes were uncovered such as “Entrance to the Cannaregio” purported to be painted by Francesco Guardi (Venice, 1712-1793).

The chemical composition of Prussian Blue is structurally complex.  The synthetic pigment is an iron hexacyanoferrate complex compound called iron ferrocyanide.  The idealized chemical formula for Prussian Blue is Fe7(CN)18.  This pigment is produced by the oxidation of ferrous ferrocyanide.  Since the cyanide of the pigment is tightly bound to the iron, Prussian Blue is nontoxic.  

Because Prussian Blue is so easily produced, it became the preferred blue of artists.  By 1713, this pigment was used by Prussian artists in painting official court portraits.  Later, Picasso (Spanish, 1881-1973) used Prussian Blue extensively during his famous “Blue Period”.

Besides painting, Prussian Blue has other uses.  The color “Midnight Blue” of crayons is made from this pigment.  The blue of blueprints is Prussian Blue.  Meanwhile, pathologists use the pigment to detect iron in biopsies.  In addition, this pigment is effective therapy for people who have ingested thallium.

A success story of alchemy, Prussian Blue became one of the essentials of the modern world.  In the 18^th Century, it became indispensable for color work.  Later Prussian Blue came to be used in textiles, printing, and other manufacturers. Combining art and science, this pigment symbolizes humanity’s ability to invent beauty out of usefulness.  Like the exploration of color, Prussian Blue was at the junction of artistic and useful pursuits.

--------------------------

Works Used:

Bartoll, Jens, “The Early Use of Prussian Blue in Paintings”, paper, International Conference on NDT of Art, Israel, May 2008. http://www.ndt.net/article/art2008/papers/029bartoll.pdf,

Boddy-Evans Marion, “All About Painting”, About.com, http://painting.about.com/,

Copeland, Jessica and Christy Rochelle, “Pigments and Binders: Prussian Blue”, Chemistry and Art, Swanee University, 1998, http://www.sewanee.edu/chem/Chem&Art/Detail_Pages/Pigments/Prussian_Blue,

Douma, Michael, “Pigments through the Ages”, Institute for Dynamic Educational Development, 2008, http://www.webexhibits.org/pigments,

Leland, Nita, “Exploring Color”, North Light Books: Cincinnati, 1998.

Lowengard, Sarah, “The Creation of Color in 18^th Century Europe”, Columbia University Press, 2006, http://www.gutenberg-e.org/lowengard/,

Art and Nature: The Alchemy of Blue (1 of 2)

Prussian blue

The primary color blue was difficult to obtain naturally.  In Ancient Egypt, blue was regarded as a sacred color.  The Egyptians experimented with various elements until they created the first synthetic pigment – Egyptian blue.  This formula for blue pigment was used throughout Europe until the Fall of the Roman Empire in the 5^th Century, when it was lost.

After that, people had several unsatisfactory choices for blue paint.  For example, created from lapis-lazuli that had to be transported from Afghanistan, ultramarine color was more costly than gold.  Meanwhile, the color indigo often turned black with age, and was not very versatile.  Also azurite and other copper-based blues often changed to green.  Creating a useable blue was imperative for painters everywhere. Knowing that the color blue was created once, artists through the ages experimented in search of a replacement formula. 

When Prussian Blue was made available in the early 1700s, it took Europe and later Asia by storm.  The first synthetic pigment of the Modern Era, Prussian Blue became widely used by printers, manufacturers, and others.  In fact, it was the synthetic pigment most widely used from 1708 to 1970, when phthaloryanine blue replaced it.

Prussian Blue was first mentioned in a letter written by Johann Frisch (German, 1666-1743).  He was promoting its virtues to Gottfried Leibniz (German, 1646 – 1716), the president of the Royal Academy of Sciences in Prussia in 1708.  Frisch, the product manager who oversaw the manufacture of Prussian Blue, sent product samples throughout Europe.

The apocryphal story of how Prussian Blue came about centers on the discovery being an accident.  This pigment was created through serendipity. Colormaker (Johann) Diesbach (German) was trying to create a red pigment in his laboratory in 1704.  Diesbach mixed iron sulphate with potash that was accidentally contaminated with blood.  What was created by this accident is the chemical compound of iron ferrocyanide.  Frisch, Diesbach’s supervisor, improved the original formula to make the pigment more stable.

Through Frisch’s active promotion, Prussian Blue became widely used in Europe by 1710.  He named the new color, “Prussian Blue”.  As the use of the pigment spread across Europe, it became also known as “Berlin Blue” and “Parisian Blue”.  Since different manufacturers used local supplies, slightly different hues of this pigment came into being.  Some of these hues were known as “Celestial Blue”, “Haarlem Blue”, and “Hamburg Blue”.  However, the generic name for Prussian Blue is “iron blue”.

The exploration of color in the 18^th Century was more than simply an artistic pursuit.  It was also a scientific and philosophical one as well.  The examination of “color” was the junction of practical and aesthetic pursuits during this time.  For example, the invention of Prussian Blue crossed many disciplines.  Manufacturing the pigment involved colormakers, apothecaries, drysalters, and chemists.  No one group had total control over the process of making the paint.  Conflicts arose prompting the eventual breakdown of traditional guilds, and the rise of modern manufacturing methods.