Dear All, >From my time at Kew Gardens I picked up a couple of bits of information which might be of interest... Alder, often found growing near river banks or in damp places (at least in England!), was used for lock gates and also for clogs since it resists the effects of getting wet and drying out very well. Presumably if it was used for clogs it must also be fairly durable.
I have no idea as to the closeness of its grain or its stability, but it might be worth a try. Incidentally, it was the wood of choice for producing charcoal for gunpowder! David Higgon London
