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Mycoparasitism by some white rot fungi on blue stain fungi in culture
1986 - IRG/WP 1304
When studying biological control of blue stain an interesting phenomenon of parasitism by some white rot fungi on blue stain fungi has been encountered. The majority of the 22 tested white rot fungi act parasitically upon blue stain fungi. The most interesting species among them is Bjerkandera adusta (Willd. ex Fr.) Karst., causing almost complete or complete decoloration of the hyphae of the blue stain fungi in culture on agar substrate. Obviously, complex enzyme reactions are involved; the main role probably performed by peroxidases. Bjerkandera adusta (Willd. ex Fr.) Karst., acted similarly upon blue stained wood, which was rapidly bleached.
R Benko, B Henningsson

Theory of Aesthetics – Charm in Furniture and an Aesthetic Evaluation of Bleaching of the Natural Color of Wood through the Application of Experimental Bleaching Process
2007 - IRG/WP 07-30424
This paper consists of mainly three sections: In the first section, brief information is given on the theory of aesthetics as a branch of philosophy, historical progress of the aesthetics theory is summarized within the context of the term “beautiful”, and aesthetic values as well as the color and aesthetic effects of color in preparing the designs are explained. In the second section, relation between the wood and color is discussed from the viewpoint of aesthetic value, and information is given on the proposed method for bleaching the natural color of wood to some degree in order to develop the aesthetic value and increase the existing charm performance. In the third section, the bleaching methods applied for Scotch pine, Oriental beech, and Black poplar by using different hydrogen peroxide recipes for each are introduced, and the results obtained are evaluated from an aesthetic point of view.
I Usta

Effects of bleaching process on the roughness values of wood surfaces of Lebanon cedar (Cedrus libani A. Rich.) and Black poplar (Populus nigra L.) using NaOH (sodium hydroxide), H2O2 (hydrogen peroxide) and Ca(OH)2 (calcium hydroxide)
2008 - IRG/WP 08-40403
Technical progress in the wood industry has been rapid in recent times. In this case, the quality assurance of the consumer products aligned with aesthetics value appears as one of the most important parameters. Because of the outer appearance of goods exert an effect on customers, interest in production of high quality surfaces of wooden commodities has increased essentially based on the surface smoothness (and/or the surface roughness of wood) aiming to reach the customer-oriented quality criteria. An aesthetics behaviour is being more influenced than the functional situation of the merchandise when the customers making the decision to buy wood products. It has been well estabilished that some of the properties of wood material (i.e. density, porosity, moisture content, fiber directions), and the wood machining process and its conditions (i.e. kinematics of the cutting process, wood sanding process) make the surface smoothness of wood problematic. There is a lack of information about the effects of bleaching process (i.e. one of the special technical ways to increase the aesthetics of wood products) on the smoothness of wood surfaces despite numerous reports published on the machining tools and the cellular structure of wood. In this study, therefore, effects of bleaching process on the surface roughness of wood was investigated for Lebanon cedar (Cedrus libani A. Rich.) and Black poplar (Populus nigra L.) using the bleaching chemicals NaOH (sodium hydroxide), H2O2 (hydrogen peroxide) and Ca(OH)2 (calcium hydroxide) by the two prescriptions with or without calcium hydroxide.
I Usta, E Aydinlar

Plasma-assisted bleaching of blue-stain from lodgepole pine wood
2017 - IRG/WP 17-40799
We hypothesize that plasma will etch wood and fungal hyphae in blue-stained lodgepole pine, and increase the ability of hypochlorite bleach to remove discolouration from blue-stained wood. Blue-stained lodgepole pine wood was exposed to a glow-discharge plasma derived from water, and the surface wettability, permeability and colour of the treated wood was measured. Plasma-treated wood was dipped in sodium hypochlorite bleach and the colour of the blue-stained wood was re-measured. Scanning electron and light microscopy was used to observe changes in the microstructure of plasma-treated blue-stained wood. We collected hyphae from the blue-stain fungus Grosmannia clavigera and used scanning and transmission electron microscopy to examine the effects of plasma on the structure of fungal hyphae. Plasma treatment increased the wettability and permeability of blue-stained lodgepole pine sapwood and removed some of the blue-discolouration from the wood. Plasma modified the microstructure of lodgepole pine wood by etching bordered pits and cell walls at wood surfaces. Bleaching of blue-stained wood by sodium hypochlorite bleach was significantly improved by plasma pre-treatments. The effectiveness of the plasma pre-treatment at removing blue-stain was influenced by the duration of the treatment. Plasma etched hyphal walls of the blue-stain fungus and degraded melanin. Our results demonstrate that plasma treatments are able to remove the discolouration from blue-stained wood, and increase the effectiveness of a bleaching agent because they degrade and remove blue/black fungal hyphae, open-up bordered pits and enable more of the bleach to be absorbed by wood. The development of plasma etching devices capable of operating at high speed and atmospheric pressure are needed to develop plasma-assisted bleaching processes that can be used commercially to remove fungal staining from wood.
A Jamali, P D Evans