Kiln Drying Services in Scotland
There are ASHS members in most parts of Scotland who offer a kilning service to customers who have hardwood planks and boards that require kiln drying. It's important to have your wood kilned by someone who has experience of drying hardwood as different species have different drying schedules, which will also vary according to the condition of the wood.
Poor kilning can lead to a lot of problems, which may in extreme cases make the wood unfit for the purpose intended.
Its best to enquire well in advance if you do have wood that needs kilning, in order to ensure that your wood is ready when you need it. Any kiln can only work to its capacity, and drying times cant be speeded up, even if the kiln is in great demand. Note that most ASHS members will ask that the material is well air dried in advance of kilning.
Technical Information on Kiln Drying
Kiln drying is essential for any hardwood that is destined for interior use. All floors, skirtings, doors, kitchen worktops, furniture, and interior panelling are kiln dried. Wood is hygroscopic that is, it absorbs and releases moisture until its moisture content is in equilibrium with its immediate environment. A piece of wood that has just been cut from a log has a very high moisture content. It has water in the cell cavities and in the cell walls. As wood dries out, it first gives up water in the cell cavities this doesnt affect its structure or shape. As it dries out further, it begins to lose water from the cell walls, and this, in a sense, is where the trouble starts. The wood shrinks, but it doesnt shrink equally in all directions. Unless the drying process is properly controlled, this unequal shrinkage can result in warping (cupping, twisting and bowing) splitting (large obvious cracks up the centre of boards) and checking (hairline cracks on the surface of a board or honeycomb checks in the inside).
Dimensional changes will also occur after the wood has been dried. These changes are generally referred to as movement. Movement is the woods response to seasonal and other changes in the temperature and humidity of its immediate environment. It can lead to cracks, loosening of joints etc. Gaps appearing between floor boards are a classic example, but one which shouldnt happen with properly kiln dried flooring, unless it has been left sitting around and had a chance to absorb moisture after it has been dried.
The main reason for kilning timber is to reduce movement, i.e, to prevent as far as possible dimensional change after the wood has been made into furniture, windows etc. It is important to recognise that extreme interior variations in heat and humidity will lead to movement.
There are other advantages associated with kilning. Most strength properties increase as timber dries, it becomes lighter in weight, and any fungi as well as some insect pests dont survive in dry wood.