Abstract:Opportunities for alternatives to synthetic textile dyes are of increasing importance as the world looks to minimize its ecological footprint. Fungal pigments within a unique class of wood-rotting ("spalting") fungi have been under investigation for several years as a possible solution, and have been shown to be ideally suited as textile dye coatings. Unfortunately, the solvent currently in use for these colorants is dichloromethane (DCM), which is an environmental problem as well as a potential human carcinogen. Recently, researchers found that the pigments from Chlorociboria species, Scytalidium cuboideum, and Scytalidium ganodermophthorum could be carried in some natural oils, which opened up a potential method of delivering pigments onto a host of substrates without utilizing DCM. Although the pigments can be carried in oil, no testing has thus far been conducted as to how oil affects the binding properties of the pigments onto textiles, or how the oil might affect the pigments directly. In this paper, the pigments produced by three well-known wood-rotting fungi were carried in raw linseed oil and applied to cotton, polyester, and nylon. Only the red pigment produced visible color change on the textiles. Cotton and polyester showed the greatest color change when the pigments were dripped onto the fabric, while polyester showed the most color when the textile was submerged into the pigment solution. Unfortunately, the colors faded significantly for all the tests except the saturation test. This indicates that while natural oils may be excellent, nontoxic alternative carriers for DCM, the pigments are not stable within them except at very high concentrations, and therefore natural oils-including raw linseed oil-are not ideal for use in conjunction with these pigments.

Identification of effective natural dyes with the potential for low environmental impact has been a recent focus of the textile industry. Pigments derived from spalting fungi have previously shown promise as textile dyes; however, their use has required numerous organic solvents with human health implications. This research explored the possibility of using linseed oil as a carrier for the pigment from Scytalidium cuboideum as a textile dye. Colored linseed oil effectively dyed a range of fabrics, with natural fibers showing better coloration. Scanning electron microscopy (SEM) revealed a pigment film over the fabric surface. While mechanical testing showed no strength loss in treated fabric, colorfastness tests showed significant changes in color in response to laundering and bleach exposure with variable effects across fabric varieties. SEM investigation confirmed differences in pigmented oil layer loss and showed variation in pigment crystal formation between fabric varieties. Heating of the pigmented oil layer was found to result in a bright, shiny fabric surface, which may have potential for naturally weatherproof garments.