Where Growth Meets Decay

Fungal pigments stain wood with surprising beauty

Bio-artist Sara Robinson works at intersections, at places where nature, ideas and emotions crisscross and often collide. She revels in the contrasts and contradictions inherent where growth meets decay, science meets art, reverence meets revulsion.

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Pink, green, and yellow stains from several fungal species grace this bowl of curly soft maple, along with “zone lines” and white rot.

For Robinson, an assistant professor in Wood Science and Engineering, all these tensions come together in the wooden bowls she turns on a lathe: gleaming, satiny bowls that are both functional and ornamental, practical and beautiful. Made of hardwoods like curly soft maple, sugar maple, box elder and buckeye oak, the bowls are adorned with pigments made by fungi whose ecological role is, ironically, to decompose wood. For Robinson, it’s the quintessential contradiction.

“Wood is held in high esteem by humans, while fungus is disdained,” she says. “It’s an emotional conflict.”

Reminiscent of watercolor washes, shades of pink, blue and blue-green splash across bowls whose shapes echo the anatomy of the wood. Others have a bleached look after she treats them with white rot fungi. Still others are etched with lines of black and brown, “zone lines” that result from fungal antagonism — two species duking it out for territory. “It’s a war story,” Robinson likes to joke.

Dead Man’s Fingers

As Robinson explains, a bio-artist is one who creates art with living organisms. “Bio-art,” she says, “blurs the lines between science and art.” Her organisms of choice grow secreted in forests, the trees stretching toward the sky, the mushrooms skulking on the ground, their fruiting bodies popping up on the decaying logs they digest with enzymes. The mushrooms’ common names suggest their odd or whimsical shapes: dead man’s fingers (Xylaria polymorpha), green elf cup (Chlorociboria aeruginascens) turkey tail (Trametes versicolor). Machete in hand, Robinson has even hacked through a Peruvian rainforest and battled poisonous tangarana ants to hunt for fungi with fabulous tints. “We found some crazy colors!” she reports.

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While scouring a Peruvian rainforest for specimens, Sara Robinson collected this fungus from the species Xylaria, the genus that contains dead man’s fingers.

The “extracellular” pigments these fungal species produce, possibly to protect themselves from UV damage or incursions by other fungi, create a natural stain in contact with certain wood species. “Because of their role in the environment,” she says, “these colors are very stable, persisting in sun and rain.”

Since the Italian Renaissance, artists and woodworkers have used naturally tinted woods in panels and veneers. Violin and guitar makers have used them in musical instruments. Now, Robinson is helping to lead a resurgence of the art, called “spalting,” which adds value to wood that would otherwise bring little to the marketplace. She regularly advises woodworkers and is among a small group of artists and scientists who are taking spalting to new levels with support from the wood-products industry.

“Spalting is a value-added wood product that can be done to really low-value wood,” she says. “So you can spalt something like aspen, which has no real inherent value as a woodworking wood. Before, it was just firewood. Now, it’s a precious wood that can be sold to woodworkers and wood turners, who are mostly retired people who shop. There’s money to be had here.” Home improvement companies, too, are interested in mass-producing spalted wood for flooring and paneling, Robinson says.

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This detail of an intarsia (wood inlay) is from the pulpit in St. Mary’s Church in Greifswald, North Germany, made by Joachim Mekelenborg in 1587 and stained by Chlorociboria.

Widely known in the woodworking blogosphere as “Dr. Spalting,” Robinson recently was dubbed by a blogger named Cody as “perhaps the foremost authority on spalted wood,” and by Tree Feller as “a bonafide expert on spalting (PhD).” At age 31, with some 25 peer-reviewed articles published in journals like Applied Microbiology and Biotechnology and Wood Science & Technology, she clearly has the academic creds as well as the crafter chops. Her research has ranged from seeking methods of minimizing strength loss while maximizing pigment production, to running experiments on the effects of wood pH and copper sulfate in stimulating pigments. There’s a lot more science that needs to happen, including toxicity testing, before spalting hits the mass market.

Pigment Precision

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The pink stain on this aspen bowl is from Scytalidium cuboideum.

In her lab, Robinson opens drawer after drawer full of petri plates, stacked three or four deep. One by one, she holds the plates up to the light. The fungi growing inside create branching forms in colors from deep violet to bright yellow. On the shelves above are vials of pigments she has extracted from the plate cultures. On the counter sits a series of test strips in wool, cotton and acetate, revealing another direction for fungal pigments: spalted fabric.

“We collect the fungi, culture them in the lab and make pure cultures for inoculation into the wood,” she says. “Our process takes the guesswork out of spalting.” That precision is what will make fungal pigments commercially viable for industry.

Over in the College of Forestry woodshop, blocks called “rough blanks” taken from 22 species of native Northwest trees are being treated with fungal pigments in plastic bins. It takes about three months for the color to infuse the wood. Once the blanks have dried, Robinson will settle in at her lathe, turning bowls in a flurry of sawdust. Her finished bowls are represented by Michigamme Moonshine Art Gallery in Michigan. She exhibits her work worldwide.

Which brings us back to the question, is spalting a science, or is it an art? Robinson challenges the very question and the assumptions that underlie it. To her, science and art are one and the same, both driven by discovery and creativity. “The only difference I can see,” she says, “is that scientists have lab notebooks.”

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See photos and information about spalting workshops on Sara Robinson’s website.

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