A woodturner will always try to use the most interesting and beautiful hardwood varieties for making wooden bowls. Some of the best turning timber cannot be bought, it has to be found.
Look out for timber with burrs or spalting, which can make specially attractive pieces. Burrs are the twiggy, lumpy growths sometimes found on the side of a tree. The wood here has very small, tightly packed knots, giving a very striking and complex figure, though very often with small cracks and fissures.
Spalted timber can have spectacular patterns, with dark lines and areas of different colour made by the harmless organisms that once grew in the log. Different kinds of spalting give different effects – sometimes single crisp black lines, or pairs of closely-spaced parallel lines wandering over the wood, sometimes a cloudy variation in colour without sharp boundaries. Spalt colours may include patches of chocolate brown, white, green, black, orange, red or yellow. Often the colours are clearly defined and separate. Because of the great variation even within one piece of selected turning timber, there can be considerable differences in appearance between two similar items made from that piece. Some timber may have small bark inclusions, where the wood has grown over part of the bark. Sometimes there are meandering tracks or holes, the evidence of past insect attack.
Garden trees often have coloured streaks in the wood caused by nails. The tree grows over the nails, which may be completely hidden in the middle of the log. They do not make the turning any easier. Depending on the species, the streaks may be black or purple.
Sometimes the wood has ripple figure – beautiful undulating grain that catches the light. It can appear almost as if you are looking beneath the surface, and as if the grain has somehow been folded, even though the polished surface is smooth and flat. The waves in the grain are real, and can be seen clearly when the log is split. Ripple can form where branches join, but occasionally the whole trunk is rippled. Sometimes, for example in sycamore, the ripples can be seen as small ridges on the surface of the bark of the standing tree.
Crotch figure forms where the trunk divides, or a large branch joins. Depending how the log is cut, there may be a single feathery line going across the bowl that is made from it, or a large area might be affected. Crotch figure can be spectacular and, like ripple, can shimmer as the light catches it.
All trees have heartwood in the centre of the trunk and sapwood under the bark. Often the two are similar, but sometimes there is a colour contrast, the sapwood usually being lighter. Laburnum, yew and whitebeam are species with a particularly strong contrast. Some species such as ash may have coloured streaks in the heartwood.
All these natural features can add interest and enhance the beauty of the wood and make it very suitable for decorative pieces. Such timber is fine for fruit bowls, but a wood bowl that is heavily spalted or burred or has bark inclusions is not recommended for moist food.
Sometimes, the turner will add colour, carving or other decoration to the finished item.
But good turning does not depend on colourful timber. Satisfying though it is to use highly decorative materials, many turners also enjoy using timbers such as holly or hornbeam, which may be pale in colour and without prominent grain. They give greater emphasis to the turned shape of the piece.