Alternative Carrier Solvents for Pigments Extracted from Spalting Fungi

Abstract

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.

Preliminary Exploration of the Red Pigment from Scytalidium cuboideum as a Cellulosic Pulp Colorant

“…The pigment can be incorporated in water-reliant processes such as the mat-forming stage in the paper manufacturing process [8], which allows for utilization in an array of industrial practices. Further testing will be required on paper quality after dyeing and the effects of the solvents, but previous research showed that the pigment generated by S. cuboideum can be carried in other types of solvents if necessary [37].…”

Potential Use of the Pigments from Scytalidium cuboideum and Chlorociboria aeruginosa to Prevent ‘Greying’ Decking and Other Outdoor Wood Products

“…An important factor relies in previous studies on potential solvent carriers for the pigment from spalting fungi such as [41] as it is possible to use other solvents such as acetonitrile that can replace DCM. In the specific case of the pigment from S. cuboideum it is possible to obtain the dramada crystals in high purity with the use of acetone [38].…”

Stability of the Fungal Pigment from Scytalidium cuboideum Carried in Food-Grade Natural Oils

“…A less potentially hazardous carrier is needed for these pigments to be utilized by consumers. Numerous attempts have been made to carry these spalting pigments in less toxic solvents, none of which have had success across all three major colors [ 27 ]. This has led to the investigation into using oils as carriers for the pigments [ 28 , 29 ], as natural oils have historic uses in textiles, especially in waterproofing applications.…”