Microbial dyeing—infection behavior and influence of Lasiodiplodia theobromae in poplar veneer

To seek a greener and more environmentally friendly wood dyeing method, this paper conducted a 35 days microbial dyeing test on bleached poplar by reversely utilizing the blue-strain fungus lasiodiplodia theobromae in poplar. The effects of microbial dyeing on the color properties, chemical composition, micromorphology, and surface properties of poplar veneers were studied. The brightness value and the reflectivity of bleached poplar gradually decreased with the dyeing time, the reflectivity of the front of the veneer was generally maintained at about 5% after more than 14 days dyeing time, and the K/S values gradually increased in the range of 400–700 cm−1, which were all greater than four. After 35 days of biological staining, the hypha of lasiodiplodia theobromae has generally penetrated the poplar veneer with a thickness of about 0.5 mm through the transverse structure (wood ray, vessel) but showed little effect on the chemical composition of poplar. The subtle difference of the chromatic aberration between the light and water wash could be observed after the dyeing time exceeded 14 days, and the chromatic aberration after illumination and washing was below 3NBS and 1NBS, respectively. In addition, the wettability and tensile modulus of veneer after dyeing showed minor changes. •A greener and more environmentally friendly microbial dyeing method for poplar wood was tested and studied.•The brightness value and the reflectivity of poplar veneer gradually decreased with the dyeing time were evaluated.•The dyeing veneer shows a perfesct fastness to illumination and washing after the dyeing time exceeded 14 days.•The wettability and tensile modulus of veneer after dyeing showed minor changes.