Arts and sciences

Behind every art is science.

Of course, you can produce beautiful art without knowing any scientific details; the Renaissance masters created gorgeous paintings without knowing the exact chemical composition of their paints.  It's amazing, really, that they accomplished what they did, combining their astonishing talents and aesthetic senses with materials developed using what amounted to trial-and-error.

I wouldn't consider myself an artist, but I do play around with clay, and I've gotten the chance to geek out over the scientific side of pottery -- specifically, glaze chemistry.  Glazes are generally made of four ingredients -- a glass-former (usually some form of silica), a flux (which lowers the melting temperature of the mix and make it flow), a refractory material (to give it stability and viscosity), and a colorant.  One of the first things I learned when I started making pottery, though, is not to assume the final product after firing to 1200 C will be the same color as the raw glaze; in fact, the reverse is usually true.  Here's a kiln load, coated with various raw glazes, before firing:

And the same kiln load after firing:

The changes that occur during firing always strike me as something very like alchemy.  Even knowing a bit about how they work -- and what I know is, honestly, little more than a bit -- there's still an unpredictability about glazes that make them fun, exciting, and occasionally exasperating to work with.

I was reminded of my trials and tribulations -- and occasional triumphs -- with glaze chemistry as I was reading a paper in Proceedings of the National Academy of Sciences - Nexus a couple of days ago.  Called "Marangoni Spreading on Liquid Substrates in New Media Art," and written by San To Chan and Eliot Fried of the Okinawa Institute of Science and Technology, this paper looks at the creation of intricate and beautiful fractal patterns using little more than acrylic ink and paint, water, and rubbing alcohol.

The technique involves applying tiny droplets of thinned acrylic ink onto a painted surface.  The irregularities in the surface draw the liquid away from the point where it is applied, and the design develops as you watch, creating branching patterns resembling snowflakes, neurons, or lightning.  Just as with ceramic glazes, the exact mix of the various ingredients can drastically change the results.  The process works because acrylic paints and inks are thixotropic, meaning that their viscosity changes when they're stirred or shaken (a common thixotropic substance is ketchup -- which is why you have to shake it or it won't pour).  The water and alcohol change the viscosity, and in combining the ingredients there's a sweet spot where the mixture is viscous enough to hold together into threads on the painted surface but not so viscous that it doesn't move.

"In dendritic painting, the droplets made of ink and alcohol experience various forces," said San To Chan, who co-authored the study.  "One of them is surface tension -- the force that makes rain droplets spherical in shape, and allows leaves to float on the surface of a pond.  In particular, as alcohol evaporates faster than water, it alters the surface tension of the droplet.  Fluid molecules tend to be pulled towards the droplet rim, which has higher surface tension compared to its centre.  This is called the Marangoni effect and is the same phenomenon responsible for the formation of wine tears -- the droplets or streaks of wine that form on the inside of a wine glass after swirling or tilting."

"We also showed that the physics behind this dendritic painting technique is similar to how liquid travels in a porous medium, such as soil," said Eliot Fried, the study's other co-author.  "If you were to look at the mix of acrylic paint under the microscope, you would see a network of microscopic structures made of polymer molecules and pigments.  The ink droplet tends to find its way through this underlying network, traveling through paths of least resistance, that leads to the dendritic pattern."

I love knowing the science behind the arts (although I must admit that the mathematics in the paper about dendritic art lost me pretty quickly).  It was great fun, for example, that the fiddler in the band I was in for ten years was a physics professor at Cornell University and taught a class called The Physics of Music -- she more than once told me things about how my instrument worked that I honestly hadn't known (such as why flutes go sharp when they warm up).  

I don't know about you, but knowing the science of how things work enhances my appreciation for their beauty.  I've loved Bach's music ever since I first heard it as a teenager; but now, understanding how fugues and canons are constructed makes my wonderment over pieces like the astonishing A Musical Offering that much more profound.  Likewise, my knowing a little about glaze chemistry enhances my enjoyment of the beauty of the results.

Science itself is beautiful.  And when you combine it with art and music, you have something truly magical.

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