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S E L E C T I N (i AND BUTINC SlITABL E W O O D

It is a slow and risky business to return it to its original shape by wetdng the dried surface - it may bccome so wet that mould spores takc root and discolour the wood. The same damage can occur if wet wood is kept in a plastic bag to retard moisture loss. It is best to disinfcct the wood first when doing either of these.

Less Obvious and Unpredictable Problems with Wood

Interlocked and spiral grain can usually be detected on the outside of a log or on a prepared piece of wood. Knots and inclusions of bark {see Fig 2.12) or even forcign objects such as stones, nails and arrowheads sometimes do not appear until the carving is well advanced. Dead knots sometimes rot while the tree is growing around and over the stump of a branch {see Fig 2.6), and you may unexpectedly discover them as cavitit*s filled with crumbs and stains spreading outwards. It is to meet such eventualirics that you should keep all offeuts so as to be able to patch the hole with maiching grain. I have also encountered very hard, dark patches in some woods which quickly dent chisel edges. Thcsc may be silica deposits formed in response to damage to the growing trcc (Fig 2.18).

Reaction Wood

Timbcr merchanrs do not usually sell branch wood but they may sell wood from leaning trees, which can havc the same characteristics. Yet another difference between softwoods and hardwoods is in the way they rcact to leaning (Fig 2.19). Softwoods put on much broader rings on the undersidc of a branch or leaning trunk. This reaction wood is strong in compression and consequently called compression wood. Conversely, hardwoods tend to develop morÄ™ on the upper side. This wood is strong in tension and is called tension wood. Such wood is liable to distort and markedly change a camng when

Fic. 2.18 Tern by Dick Onians carved in green field mapie immediately afier being blown down in order to eliminate splitting. The black mark is a silica deposit which is almost uncaruable.

FlC 2.19 Reaction wood. Compression wood of Cedar of Lebanon (lefi) and tension wood of ash (right). NotÄ™ the offeentre pith and the irregular colouring. The right-hand side of the ash bas been cttt with a chisel to show the adoantage over the duli sandedfinish on the left.

tensions are releascd by working it (Fig 2.20). Compression wood may be brittle and tension wood may be furry when rip-sawn. Reaction wood is usually recognizable because the pith is off to one side. Sometimes this is not so in hardwoods, but in these cases reaction wood often revea!s itself by its unusual colouring.

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