A now ubiquitous pigment squeezed out in gobs on every art student’s palette used to be so expensive that Michelangelo left a painting unfinished for want of the mineral. For centuries the scarcity made the color the most precious of the palette, so it was reserved for the garments of the most sacred figure. You’d think that would be Jesus, but throughout art history he has a well documented sartorial deficit. So the blue falls to the next holiest, his mom, Mary. Here she isn’t in the lower righthand corner of Michelangelo’s The Entombment.
A quick unpacking of the name ‘ultramarine’ can give you an idea why it was more precious than gold to artists. Its latin form (ultramarinus) means “beyond the sea.” Originally created by grinding up lapis lazuli, a mineral found almost exclusively at the Sar-i-sang mines in Afghanistan. The long journey over land and sea gave it its name and contributed greatly to its high price. Not helping one bit, turning raw lapis lazuli to an natural ultramarine pigment is labor intensive, requiring a blue-fingered craftsman to add the crushed mineral to a host of chemicals (linseed oil, rosin, resin, wax, turpentine, mastic) making a paste, and, as a contemporary recipe describes it, “suffer it to digest for a month.” The blue crystals then wash out in warm water, and the process should be repeated several times to increase the purity of vibrant pigment.
Luckily for painters and other people with eyes, the Societé pour l’Encouragement d’Industrie (a real, not at all made up institute) funded a contest in 1824 that would award a whole mess of francs to whoever could produce a formula for a synthetic version. In 1828 a French chemist and a German chemist both submitted processes that produced slightly different variants of the newly synthetic pigment.
Jean Baptiste Guimet and Christian Gottlob Gmelin (I think you can figure out who’s from where) submitted slightly different variations of a process within a month of each other. Guimet claimed to have discovered the process in 1826 but kept it secret and the Societé pour l’Encouragement d’Industrie awarded their fellow countrymen the prize (quelle surprise!) which explains the occasional labeling of the paint French Ultramarine. By 1830 each mans countries was home to a factory producing the synthetic pigment. Occasionally Guimet Blue and Gmelin Blue still appear on tubes of Ultramarine Blue paint. Dropping the price by an order of magnitude brought the color to ubiquity with half a century to spare before the invention of impressionism.
So how’s it made and what’s the difference from the natural version?
The composition of the synthetic and natural ultramarines are remarkably similar, and the difference comes from the natural’s impurity. When viewed under the microscope (pictured at top) the synthetic ultramarine has a smaller and more regular pigment size than the natural version which is uneven and speckled with white impurities that extend the color and make it more transparent. I did not get actual lapis lazuli to view under the microscope because Afghanistan is still a hard place from which to source materials.
Here’s the difference, synthetic on the left, natural right. They hardly look like related colors at all. The natural ultramarine required underpainting plus multiple layers to achieve its rich and deep blue in art historical examples.
The process of production sounds complicated but can be simplified to heating a list of ingredients in a closed furnace, then cooling and washing. If you had a working knowledge of chemistry your ingredient list would look like this: Kaolinite, Sodium Carbonate, Anhydrous Sodium Silicate, Anhydrous Aluminum Silicate, Sulfur
And in English : china clay, soda ash, coal, charcoal, quartz, sulfur.
And if you want to dumb it down a shade: a particular type of clay, water softener, burned wood, a very particular type of salt, a very particular but different type of salt, and sulfur.
You’ll notice sulfur does not simplify, that’s because it’s an element, and elements do not get simpler, they are fundamental. That’s pretty important. Side note: Sulfur is awesome, really, really awesome. Most elements are just hunks of grey metal. Not sulfur. In its solid form it is bright yellow, when melted it turns red, and when burned its flame is blue!
So you heat all this stuff up in a closed furnace for an hour, remove the brick and wash it in pure water and you get a quantity of a mineral that can be dried and ground into the pigment. The final product bears a marked similarity to lazurite, the compound in lapis lazuli that gives the historical ultramarine its blueness. The standard notation has it looking something like this: Na8-10Al6Si6O24S2-4
Does this complex sulfur-containing sodium silicate look complicated? Well by most accounts ultramarine is the most complicated of all the mineral pigments, so well done sticking out so far.
A fun vocabulary note from this, the word ‘anhydrous’ means without water, but it doesn’t mean just dry. If you add water to salt, say, then let it dry out until it didn’t look wet anymore, it would nevertheless still have water in it. The structure of the salt crystals that formed would contain water, and in a reaction those pesky hydrogens and oxygens would royally screw up the royalist of blues. Beware of oxygen, it will ruin anything.
Explaining what makes ultramarine pigment blue is not simple. The shortest and easiest way to say it is probably “the sulfur does it.” More technically it is a particular ion of sulphur that does it (an ion being an atom with unequal positive and negative parts, so it carries an electric charge). Normally those ions are unstable, but in this case they are contained in a cage made from all the other letters in that formula above which keeps it stable over time. If you add anything to ultramarine pigment that breaks down that cage, the sulfur will bond to oxygen (most likely scenario on Earth) and will fade like it did in this Vermeer painting. In Vermeer’s time the cushion of the chair was brilliant pure ultramarine – today it has a faded grey patina.
Speaking of Vermeer, time for an art history tour! Archaeological evidence at the Afghan mines suggests mining of the blue rock began at least 6,000 years ago. Lapis lazuli adorns artifacts from all over the ancient world. It’s mentioned several times as a measure of wealth in the Epic of Gilgamesh from Mesopotamia. When the Old Testament mentions sapphire, the authors are likely referring to lapis lazuli, as sapphire was not seen in the area before the Roman empire. Ancient Egyptians, Mughals, and Persians all worked the stone and left examples that have time traveled through centuries to us today.
The first known use of lapis lazuli turned into ultramarine painting pigment are in Zoroastrian and Buddhist temples in Afghanistan near the sites where the blue stone is mined. The best example used to be the Bamiyan Buddhas, which were giant statues carved into the side of a mountain with paintings decorating the grottos they inhabit, but they were destroyed by people who have a ridiculous problem with pictures of sentient beings (even the made up ones).
This is by far my favorite example:
Around 1000-1100 AD the ultramarine paint which can be traced back to the mines in Afghanistan, starts showing up in Anglo-Saxon and Norman illuminated manuscripts, as well as Chinese and Indian paintings in their distinctive styles (which seems to be scroll vs. mural, respectively). Then the Renaissance happens across Europe. It was pretty great art-wise, and most of the lapis lazuli-turned ultramarine of the time traveled through Venice.
Closer to our own time, art history types love to cite Yves Klein in reverential tones because he patented his own blue, creatively named Yves Klein International Blue.
The pigment is entirely synthetic ultramarine. The distinguishing characteristic is the binding agent, which keeps the paint looking as much like a pure pigment as possible. I’ve seen it, and works made with this blue have a peculiar effect in person. They seem to create space, or make the space seem more dense, as if this part of reality is operating by a different set of fundamental rules. They do not translate well to pixels, so I won’t put an example here, it wouldn’t do any good. I highly recommend setting eyes on one, it’s rewarding experience. France is a good place to look.
The binding agent is a Polyvinyl Acetate, a complicated salad of sounds that acts as a deterrent to understanding. Two examples from this group of thermosoftening plastics are better known by their more common names, Wood Glue and Elmer’s Glue. So Yves Klein mixed glue with blue. Well done.
Klein developed the blue with a pharmaceutical firm Rhône-Poulenc, which later developed Chlorpromazine, an antipsychotic medication that is used to treat disorders such as schizophrenia and bipolar disorder. Good on them for helping out more artists than just Mr. Klein.
And I’ll end this on a fun dystopic digression. The production of synthetic ultramarine produces sulfur dioxide that is vented into the atmosphere. That same molecule spews out of erupting volcanoes and has been shown to be remarkably efficient at cooling the earth by reflecting away a larger percent of sunlight (with the added side effect of influencing artists [Turner] with its increased light scattering, as in the 1815 eruption of Mount Tambora which produced dazzling sunsets with its stratospheric deposits). Natural calamity seems to inspire a plethora of weird and dangerous climate engineering ideas to offset global warming. One such idea is to release vast amounts of sulfur dioxide into the high atmosphere to reflect sunlight. Basically an artificial volcano could cool the earth temporarily, bringing with it a sulfur rich atmosphere that can scatter more sunlight which could more intensely color the skies. Our climate engineered future might have the heavens inspired by Titian.