UCLA

Spalting is the result of fungal metabolic processes that create unique, colored patterns inside of wood. As such, spalted wood has been historically prized for its beauty. Fungal pigments not only beautify wood through the spalting process though, they also impart it with strong environmental resistance. This is owed to the fact that fungi secrete pigments in wood for use in capturing and defending resources necessary for survival against competing fungal species. Pigments also provide protective properties for fungi such as light and ultraviolet (UV) resistance, bacterial and insect resistance, and prevention of desiccation in extreme environmental conditions. For these reasons, there is growing interest in fungal pigments due to their light fast, color fast, and UV light stable properties. In addition to their extraordinary environmental stability, these naturally sourced pigments are also affordable and sustainable.Spalted wood is very rare to find in the wild as the fungi require very specific environmental conditions for these processes to occur. In 2007, Dr. Seri Robinson spearhead research into spalting fungi. Robinson, a professor at Oregon State University and bio-artist, developed a process in which to extract pigments from three fungi species and use them to artificially induce spalting in the span of ten days, a process which previously took up to two years in the wild. The extraordinary environmental stability of fungal pigments makes them a material that could have potentially significant applications to the field of conservation including new lightfast pigmented coatings or inpainting mediums. In the literature, the spalting fungal pigments are purported to be light and UV resistant, however, their color stability has not been specifically measured nor has it been evaluated to museum standards. To assess their degree of lightfastness, accelerating aging experiments on fungal pigmented paper and wood coupons were conducted and subsequently compared to blue wool standards to extrapolate qualitative measurements. This full-spectrum light aging experiment established that fungal pigments are not more lightfast than many other natural dyes and colorants. To quantify the degree of color change, describe as ΔE*, values were calculated from CIELab measurements from before and after accelerated light aging. The averaged ΔE* values are as follows: blue pigment on paper, 8.98; blue pigment on wood, 11.70; red pigment on paper, 2.87; red pigment on wood, 6.94; purple pigment on paper, 8.98; purple pigment on wood, 14.88; yellow pigment on paper, 5.95; and yellow pigment on wood, 6.74. The results of this study revealed that fungal pigments are not significantly light stable according to museum standards. Given these results, fungal pigments in their raw form are not recommended for conservation applications, however, further study could look into their stability when incorporated into other materials.