Resistance of different wood-based materials against mould fungi: a comparison of methods

Abstract

Wood-based materials are generally prone to colonization by mould fungi and other discoloring microorganisms, but their resistance to fungal discoloration varies. Different standardized test methods for determining the susceptibility to mould fungi have been used to evaluate various wood-based materials, but the obtained results suggest that mould resistance depends on the method applied. Therefore, this study aimed at a comparative evaluation of two commonly used methods for determining the mould resistance of wood-based materials, i.e. the chamber method according to BS 3900—Part G6 and the malt agar plate method according to ISO 16869. Solid wood, wood fiber insulation boards and wood polymer composites were inoculated, incubated for different time intervals, and assessed with regard to superficial mould growth. Mould growth ratings obtained with the two methods did not correlate well, neither within one type of material nor across different materials, which can be attributed to higher moisture contents and additional nutrients available for the specimens in the agar plate test compared to those in the chamber test. It was concluded, that the experimental set up could have an overriding effect on the results of mould resistance tests.

The Impact of Microorganisms on the Performance of Linseed Oil and Tung Tree Oil Impregnated Composites Made of Hemp Shives and Corn Starch

“…It means that tung tree oil fills the pores and voids in the obtained biocomposite, as well as the valves, vessels, and tracheids in HS, consequently reducing the possibility for fungal hyphae to penetrate. Although, as Figure 3 and Figure 5 d–f show, it still occurs after 6 months of incubation with microorganisms because the time for fungus growth test plays an important role because fungus infestation risk increases with incubation time [ 43 , 44 ] as the weight loss of the samples increases. It can also be noted that the composition of biocomposite impregnated with tung tree oil includes expandable graphite as a flame retardant, which is a carbon-based material that reduces susceptibility to microbial degradation of composite materials [ 45 ].…”

Review of Wood Modification and Wood Functionalization Technologies

“…Acetylation weakens the interaction between liquid water and wood as seen with lowfield NMR spectroscopy [49,50] and from the decrease in contact angle with water [7][8][9][10]. For this reason, acetylation is expected to decrease the rate of liquid water uptake by capillary suction which has also been observed for acetylated alder [51].…”

“…In damp environments, the surface of wood may also be colonized by mold fungi. While mold fungi do not affect the strength of wood [9], and molds may grow on many surfaces in addition to wood, molds discolor wood and may present a health hazard in the indoor environment [10]. Finally, at high moisture contents, metal fasteners embedded in wood are subject to corrosion from organic acids and other chemicals [11].…”

Conditions Influencing Mould Growth for Effective Prevention of Wood Deterioration Indoors

“…It was found that softwoods generally contained higher amounts of antifungal extractives, which resulted in higher resistance comparing to hardwoods. It has also been hypothesized that the larger content of hemicelluloses contributes to the higher mould resistance of softwoods over hardwoods [19]. On the other hand, the mould resistance of heat-treated wood is only slightly improved, despite the significantly reduced amount of hemicelluloses [20,21].…”