The lengthy time periods required by current spalting methods prohibit the economically viable commercialization of spalted wood on a large scale. This work aimed to compare the effects of induced spalting in 16 Pacific Northwest woods using three common spalting fungi,Chlorociboria aeruginosa, Scytalidium cuboideum, andScytalidium ganodermophthorum, with the significantly less time-consuming treatment of these woods using dichloromethane-extracted green, red, and yellow pigments from the same fungi. For pigment extracts, the dosage required for a pigment to internally color various wood species to 30% internal coverage was investigated. With few exceptions, treatment with pigment extracts outperformed induced spalting in terms of percent internal color coverage. Cottonwood consistently performed best with all three pigment solutions, although chinkapin performed as well as cottonwood with the red pigment, and Port Orford cedar performed as well with the yellow pigment. While no wood species showed 30% internal color coverage with the green pigment solution, a number of additional species, including pacific silver fir, madrone, dogwood, and mountain hemlock showed internal color coverage on the order of 20–30% for red and/or yellow. Cottonwood was determined to be the best suited wood species for this type of spalting application.

Fungal pigments, specifically those generated from spalting fungi, are being developed for broader use in the wood and textile industry, and due to their coloration properties, may also be useful as aesthetic bamboo dyes. This paper evaluates the potential use of fungal pigments in bamboo (Phyllostachys spp.), and compares the difference between natural spalting and the direct application of extracted fungal pigments of three known spalting fungi: Scytalidium cuboideum, Scytalidium ganodermophthorum, and Chlorociboria aeruginosa. Bamboo was significantly spalted by S. cuboideum under live inoculation, while the other two fungi did not colonize. For the direct application of fungal pigments, bamboo did not develop internal pigmentation with any pigment, but did develop visible surface color for S. cuboideium and C. aeruginosa. Light microscopy and scanning electron microscopy confirmed the presence of hyphae in bamboo vessels and parenchyma. An HPLC analysis for simple sugars showed the presence of glucose but no sucrose. Results indicate that the extracted pigments of the aforementioned fungi are ideal for the surface treatment of bamboo, while only direct inoculation of S. cuboideum is appropriate for internal coloration.

The use of both naturally occurring and synthetic pigmented wood has been prevalent in woodcraft for centuries. Modern manifestations generally involve either woodworkers’ aniline dyes, or pigments derived from a special class of fungi known as spalting fungi. While fungal pigments are more renewable than anilines and pose less of an environmental risk, the carrier required for these pigments—dichloromethane (DCM)—is both problematic for humans and tends to only deposit the pigments on the surface of wood instead of evenly within the material. Internal coloration of wood is key to adoption of a pigmenting system by woodworkers. To address this issue, five solvents that had moderate solubility with the pigments extracted from Chlorociboria aeruginosa and Scytalidium cuboideum were identified, in the hopes that a reduction in solubility would result in a greater amount of the pigment deposited inside the wood. Of the tested solvents, acetonitrile was found to produce the highest internal color in ash, Douglas-fir, madrone, mountain hemlock, Port-Orford cedar, Pacific silver fir, red alder and sugar maple. While these carrier solvents are not ideal for extracting the pigments from the fungi, acetonitrile in particular does appear to allow for more pigment to be deposited within wood. The use of acetonitrile over DCM offers new opportunities for possible industrial spalting applications, in which larger pieces of wood could be uniformly pigmented and sold to the end user in larger quantities than are currently available with spalted wood.