Fungal decay is initiated at lower moisture contents in standard and tempered hardboards (18%) than in pine sapwood (26%). In contrast, in a saturated atmosphere, the equilibrium moisture contents of standard hardboard (14%) and of tempered hardboard (12.5%) are much lower than the moisture content permitting decay initiation whilst the equilibrium moisture content of pine sapwood (25.1%) approaches its decay initiation level. When immersed in water the hardboard, especially when tempered, took much longer to wet to decay initiation moisture contents than the pine sapwood but, on the other hand, the hardboards dried at much the same rate as the solid wood. It is concluded that the physical changes which occur during hardboard manufacture are such that under fluctuating service conditions, even when liquid water is intermittently present, hardboards tend to remain at risk from fungal attack to a much lesser extent than solid wood.

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