Alders spring up rapidly in riverbank areas and generally grow in clumps -- multiple smallish trunks springing from a single root system. I don't know if this is universally true, but all the alders I've seen are rather small, and I doubt that the trunks ever grow to more than a few inches in diameter.
Assuming one wants the sundial to be more than a few inches across, solid wood would have to be either taken from a large tree like oak or maple, or glued up from strips. When large trees are sawn into planks, there are several ways of making the cuts in relation to the central axis of the trunk, and the stability of the resulting boards depend on the orientation with respect to the rings, as well as to the proximity to the center of the trunk. The need for broad panels was satisfied using traditional carpentry techniques in different ways including accepting the wood's movement (i.e. doors build with stiles, rails and panels) and gluing up boards edge to edge with transverse reinforcements (i.e. tables) . Modern woodworking makes extensive use of plywood, where the tree has been "peeled" radially into veneers which can be glued back together (e.g. the ubiquitous and attractive birch veneer plywood... note that birch veneer plywood is 8 by 4 feet but birch trees are rarely more than a foot in diameter). We also now use various types of synthetic wood panels, particularly the different types of "chipboard" which contain a mixture of wood and resin. IMHO, the bottom line on wood-for-sundials is that wood is basically an unsuitable medium for this purpose, however there are some synthetic panels which have woodlike properties and may contain some wood that could work quite well. I once stopped to watch a sign being installed over a shop. The sign was one of those things where the letters are deeply incised as if they were chiseled into wood. I asked about the material and was told that it was a type of plastic. It was quite light, and seemed to have about the same workability as wood. I don't know what this stuff is called, but it might make an excellent material for a sundial. At 03:50 AM 12/17/98 -0500, you wrote: >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 > >
