Clean dirt
As published in Material Intelligence, October, 2024
Sand is hard to resist. Adults associate its pliant, fluffy texture with the white beaches of a tropical vacation. Kids immediately jump in to play with sand wherever they find it. The sandbox, both in its physical form and as a metaphorical space for working through ideas, unites people of all ages in experimental experience. Like water and air, sand is at once transient and eternal. It’s continually swallowed up and thrown ashore by the movements of the ocean. Its colors—pink in Bermuda, ochre in Malta’s Ramla Bay, black in Hawai’i and Iceland—are evidence of the rocks, lava, coral, and shells from which it is made. Like clay, sand can be made into nearly any form, even one that’s satisfyingly precise, when damp. But unlike clay, sand isn’t sticky; it holds its shape, then releases it without a fight. A sand mandala is designed to be ritually destroyed in a moment, while the sand in a Japanese rock garden may be repeatedly raked into forms that will vanish with wind, weather, and passing footsteps. It can make a mess but doesn’t leave stains, and it’s relatively easy to tidy up. We might call it “clean dirt.”
Children in a Sandbox at the Perkins School for the Blind, Watertown, MA, 1916. Courtesy Perkins School for the Blind.
Given all this, it’s little wonder that sand is the world’s play material of choice. (It was inducted into the National Toy Hall of Fame in 2021.) Children presumably began playing with it at a moment deep in the prehistory of our species. But sandboxes as we know them are comparatively recent, originating within the kindergarten movement in mid-19th century Germany; educator Friedrich Froebel created sand gardens in Berlin’s public parks starting in 1850.
The social reformer Kate Gannett Wells, head of the Massachusetts Emergency and Hygiene Association in Boston, said “playing in the dirt is the royalty of childhood,” but noted that while farm kids had plenty of access to the stuff, the urban poor had nothing but unsuitable grime. Together with a group of other Boston philanthropists, Wells arranged for a big pile of sand to be dumped in a chapel yard on Parmenter in the city’s North End neighborhood, and the first American sandbox was born. Sandboxes soon proliferated, becoming standard features of playgrounds and nursery schools across the United States. Froebel’s imprimatur gave them a certain pedagogical credibility; implicitly, this was a civilized way to have fun, in contrast with wallowing around in the mud.
Today, sand has left the box and become a discrete plaything in its own right. One innovation is hydrophobic or“magic” sand. Originally developed to help clean up oil spills, this is just ordinary sand that has been coated in a water-repellent substance called trimethylhydroxysilane. Underwater, magic sand can be sculpted into shapes, just as ordinary sand can on dry land. When removed from the water, the magic sand sculpture will disintegrate. The idea goes back a ways: in 1915, an article about “magic sand” was published in “The Boy Mechanic, Book 2: Things for Boys to Do,” published by Popular Mechanics. Under the unfortunately retrograde name of the “Hindoo Sand Trick,” the recipe was presented as a recently uncovered secret of the exotic east. “It consists of placing ordinary sand in a basin full of water, stirring the water and taking out the sand in handfuls perfectly dry,” wrote the submitter, based in Oshkosh, Wisconsin. “It need scarcely be said that without previous preparation, it is impossible to do so.” In fact, the process was hardly an international mystery; it simply involved placing sand in a frying pan, heating it with a piece of grease or wax, incorporating it thoroughly and allowing it to cool. In nature, magic sand can sometimes be found in the wake of a forest fire during which organic material coats soil particles, making them hydrophobic.
Unlike magic sand, Kinetic Sand, which comes in an array of vibrant colors, is entirely human-made. Kinetic Sand is ordinary beach sand coated in polydimethylsiloxane, and it’s also hydrophobic, but holds its shape in and out of water, so sculptural creations can be preserved indefinitely. It also doesn’t shed granules, making it clean even by sand standards. But Kinetic sand lacks the one quality that makes ordinary and even magic sand so perfectly suited to play, experimentation and brainstorming: the luxurious guarantee of impermanence. In an hourglass sand makes time visible, streaming at the merciless pace dictated by gravity. But contained within its symmetrical form is the promise of a new start: whenever time has run out, it can simply be turned over for another go. Play, similarly, is always an open-ended experiment. We would not necessarily wish every single one of our unpolished ideas to be scrutinized. That a sandcastle will inevitably be washed away, no matter how opulent or ornate its architectural features, is its bittersweet essence. The ocean consumes our working draft. Only the clams will know.