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The Fine Art of Decay

A woodworker becomes a scientist in seeking out the perfect fungal pigments

Sara C. Robinson

The Art History of Spalting

2014-05RobinsonFp209.jpgClick to Enlarge ImageAs I discovered several years later, however, pigmented wood was not unknown to the art world. There are a plethora of examples of the green-stained Chlorociboria-infected wood in European intarsia (wood inlay that uses tiny pieces of wood to make a larger picture). The blue-green wood of Chlorociboria was commonly utilized as color for grass or water, and was a prized find by many crafters. An easily accessible example is the pulpit intarsia in St. Mary’s Church in Greifswald, Germany, by Joachim Mekelenborg. In addition to blue-stained wood (common in sky areas), wood marked with zone lines was also used in intarsia. There wasn’t a technical name for such wood (“Pilz-Pigmente,” as it was called in German, literally just means fungus pigment), but artisans saw its value as a way to avoid harsh dyes and sought it out for use in their works.

2014-05RobinsonFp210botleft.jpgClick to Enlarge ImageUnfortunately, the Industrial Revolution, when handmade craft gave way to machine-manufactured products, played a large role in the decreasing interest in intarsia and naturally pigmented wood, and by the early 1900s, the use of spalted wood in wood crafts was down to a trickle. Even the arts and crafts movement, designed to raise awareness of hand-made craft, keep old techniques alive, and value the craft over machine-based products, didn’t keep this colored wood in use.

But like any beautiful thing, colored wood couldn’t stay hidden for long. In the 1970s Mel and Mark Lindquist, a father–son duo, were making waves in the craft and art scene with their use of found zone-lined wood for wood turnings. They 2014-05RobinsonFp210botmiddle.jpgClick to Enlarge Imagegained a great deal of media attention after they authored several articles about spalted wood in Fine Woodworking, the premier wood magazine of that time. These two gentlemen turned the word spalting into a name to describe zone-lined wood (its definition was later broadened by my own research). Although this reemergence of spalted wood as a craft and art tool brought naturally colored wood back into the forefront of public consciousness, the pigments were left forgotten, and zone-lined wood was hailed as the new design trend in woodturning.

Due to the emphasis on zone lines by spalted wood users, my own wood research 2014-05RobinsonFp210botright.jpgClick to Enlarge Imagein the mid-2000s began heavily focused within this area. But I also experimented with blue stains, because the fungi that produce such color are numerous. Initial experiments attempting to induce zone lines in clear lumber led to more research and more reading, and it became quickly apparent to me that spalting encompassed a much wider definition than simply black lines—even zone lines could occur in different colors. So when I began publishing my results on how to induce spalting under controlled conditions and began naming fungi that could reliably produce spalting, even though I was primarily working with zone lines at the time, I reset the definition: Spalting was any color on wood caused by a fungus.

2014-05RobinsonFp210topleft.jpgClick to Enlarge ImageWoodturners, the group most interested in spalted wood, were ravenous for information about how to improve and expand their craft. It was broadly understood that fungi were at least partially responsible for spalting, but which fungi and how best to get said fungi in the wood was still a mystery. Conjecture had ruled the gossip chain and Internet for so long that once artisans had actual fungi to experiment with, the topic exploded. With the release of my research, 2014-05RobinsonFp210topright.jpgClick to Enlarge Imageattempts to induce spalting in workshops was no longer a practice in luck, patience, and variable mixtures of leaves, wood chips, and beer (and various other amusing spalting recipes). Lab-derived directions for speeding up growth and getting a reliable result were finally available. Interest grew, along with commercial demand. So my research kept going. Eventually I became bored with zone line research, because wood with black zone lines is exceptionally easy to find in the forest. It is also easy to induce in a lab or garage, because the production of such wood only requires a log and two irritable white rot fungi. I wanted color. I turned my focus back to the pigments, notably the greens and pinks.

2014-05RobinsonFp211.jpgClick to Enlarge ImageThis turned out to be a trickier endeavor. In nature, the brighter pigments, whether in zone-line or full-coverage form, are hard to locate. True wood-inhabiting fungi will be inside the log, not growing on the surface (Penicilliums and Trichodermas, common airborne molds that only discolor the surface of wood, need not apply). If you want pigmented wood, you’re going to have to dig for it. These fungi also tend to be slower growers without any real decay ability (with one species called Scytalidium cuboideum being a glaring exception). They are usually found on logs that are already well colonized by basidiomycete fungi like white or brown rots. This means that the wood is soft, punky, and generally unusable unless you want to do historic intarsia, or to sink about $20 worth of plastic stabilizer into the wood.

2014-05RobinsonFp212.jpgClick to Enlarge ImageIt also means that color-producing fungi can be difficult to grow in a lab, where the majority of my work was taking place in plastic tubs and Petri plates. I found that Chlorociboria species are especially tricky, because isolates can take months to grow to adequate sizes and do not perform well under wood inoculation conditions. While doing postdoctoral research at the University of Toronto, my research took off in this direction: how to encourage pigment fungi to grow and produce their colors under controlled conditions. They obviously weren’t going to be motivated by money or a new car, so we had to get creative. It turned out that a simple addition of white-rotted wood, finely chipped, sterilized, and added to our standard malt agar media, was enough to get our target fungi to rapidly secrete pigment. What once took months for substandard results now took 10 days with amazing results.

2014-05RobinsonFp213.jpgClick to Enlarge ImageWe ended up with hundreds of sheets of wood fiber in the lab, pigmented with green, blue, red, pink, orange, and yellow. We were awash in a rainbow of colors we never expected to have in any sufficient amount. Suddenly, the possibilities for these fungi were massively expanded. The pigment was extractable and easy to reapply to wood where we wanted it—no fungus growth needed. The pigment also had an affinity for textiles, and our lab exploded with samples of every fiber imaginable, all brightly hued and covering every available surface.

With this breakthrough, modern spalting was born. A mixture of biology, artistry, and luck, the process developed for the lab has reduced incubation time from one to two years in the wild to about two hours in the lab, still using the same fungi.

Today, my lab in the Wood Science and Engineering Department at Oregon State University is filled with excited graduate students and undergraduates, all who have different ideas about how these pigments can be used. Nothing is off-limits—we’ve become a lab of random experiments, of both science and art. Our biggest struggle is deciding on which paths to follow first. Questions that currently interest us include: Do the pigments have any UV stability? Do they have any medical potential? Can they be used as dyes for acrylic paints or dyes for clothing? Does spalting mean wood colored with fungi that are actually grown on the wood, or can it still be spalting if the fungi are grown on a different piece of wood, then the colors transferred in a directed manner?

We are all very excited about the evolution of this ancient art. But in the end, the consumer and artist will dictate how spalted wood and extracted pigments are used, whether for beautiful, time-consuming intarsias, prefab wood veneer floor, or your next pair of running shoes. No matter where our research takes us next, it is guaranteed that it will be brightly colored and beautiful.

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