Oct 4, 2010

The Crazy History of Blue

If you're like me, you take colors for granted. You want to draw or paint? Go to your local art store and pick up a tube of whatever color you want. You can even get strange modern colors like hot pink or fluorescent yellow.

But, as it turns out, most colors were not particularly easy to find as long-lasting, quality pigments. So each one has a long history of botched attempts, less-than-adequate results, and intrigue.

Such is the story of blue!

In its long history, the color blue has been used for decorating temples, displaying wealth, creaing the Smurfs, and offering human sacrifices. The recipes for its pigment have been discovered across cultures, lost, rediscovered, and synthetically created.

Both the ancient Egyptians and the ancient Mayans discovered blue pigments. So did the ancient Chinese. Interestingly, in Egypt and China the artisans used early chemistry, baking and and mixing and reacting compounds of quartz, a copper compound, and calcium carbonate (in the case of Egypt) and quartz, a copper compound, and a barium compound (in the case of China). The similarity of the two colors' chemical formulas (CaCuSi4O10 vs. BaCuSi4O10) has caused some to posit that Chinese blue ('Han blue') is descended from the earlier Egyptian blue. However, there is nothing conclusive to prove this.

Anyone familiar with high school chemistry knows of copper ions' bluish tinge, so it makes sense that the chemical pigments would have that ion hanging about (see the 'Cu' in the formula). Mayan blue, however, was a bit more cagey. Even today scientist's aren't sure exactly what they used, though they believe it was a mixture of naturally occurring indigo plants and a clay called palygorskite. Though different in their makeup, each of the compounds has lasted for centuries: you can still see blue paint on Egyptian friezes and sculptures, ancient Chinese porcelain, and Mayan sacrificial sites. That's right: in times of drought, in order to bring the 'blue' rain, Mayans would cover someone in the blue dye and toss them into a sacrificial well. Even today, there are wells found with over ten feet of hardened blue dye on the bottom.

By the Middle Ages of Europe, however, the Egyptian insight to blue pigment had been lost. While Chinese blue objects made it to the West through trade, their pigments rarely did. Instead, Europeans would use the elusive lapis lazuli, an intensely blue stone found--at the time--only in modern Afghanistan. Needless to say, the distance and labor involved in the mining process made the stone incredibly valuable, more so than gold, in fact. Painters who couldn't afford the pigment would use azurite, a different stone that yielded a greenish-blue, which was clearly not what the artists desired.

It wasn't until the eighteenth century that a strong, resolute synthetic blue was created. And even then, it was an accident. A Berliner, named Diesbach, was seeking to create a red hue by using iron sulfate and potash. However, the potash was contaminated, so the more he added, the less red the pigment became. Before he knew it, the reaction he caused created a deep blue hue. Though he didn't figure it out, others eventually did: animal oil from animal blood had gotten into the mixture, causing a reaction that formed potassium ferrocyanide, today known as 'Prussian blue'. Artists began gobbling up the stuff, because it was relatively cheap and easy. Soon after, cerulean and cobalt blue were discovered. By the 1930's, phthalo blue had been added to the roll.

As an unintended side-effect of Prussian blue's discovery, by the 1800's, lapis lazuli, the blue stone that had been so precious to medieval and Renaissance aristocrats, was shunted aside. If anyone could have blue, they figured, why would they even bother?

Even today new blues are being synthesized, continuing a chain from ancient times to now.

And fun fact, ever notice that 'cyanide' has the word 'cyan' in it? Cyan is a derivative of the Greek κύανoς, meaning--go figure--blue. The resultant Prussian blue compound, made from iron, was called 'ferrocyanide', meaning 'iron-blue'. Chemists eventually determined that a molecule of bonded carbon and nitrogen had joined with iron; CN, therefore, became a 'cyano' group, and as an ion, 'cyanide'.

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