Wood

TIMBER

There are two main types of natural timber - hardwood and softwood. The categories softwood and hardwood do not describe the properties of timber but refer to the types of tree from which the woods are obtained.

Wood products (particularly waste from timber preparation) are often re-constituted to form manufactured materials such as chipboard.

Hardwoods

Most hardwoods are more stable than softwoods, they often have a strong aesthetic appeal. They possess many desirable properties that a designer can exploit; they have a high strength to weight ratio both in tension and compression. They are also elastic and can be laminated. The heavy/dense woods are stronger in absolute terms. Most hardwoods are expensive. However they are ideal for small scale projects:

Ash : White in colour, tough with an attractive grain but very elastic, so will withstand shocks.

Balsa : Very soft and lightweight - superb for modelling.

Beech : Very hard and tough, fine grain - machines well, good for toys.

Iroko : Similar to teak but much cheaper.

Jelutong : Fine textured, straight grain, ideal for small models.

Lime : Superb for carving patterns.

Mahogony Types : eg Sapele/Utilie - rich red colour, strong and durable. Available in wide boards.

Oak : Attractive grain, hard and tough, but expensive!

Sycamore : White, ideal for turning - can be used for food containers.

Teak : Attractive golden brown, tough strong and durable. A very multipurpose material, though expensive!

Softwoods

Softwoods are usually less expensive than hardwoods, they are lighter in weight than most hardwoods and can be used for many purposes. They are usually easy to work:

Russian Red Deal : Often called ‘Pine’ - good strength to weight ratio. Attractive sometimes ‘knotty’ appearance.

Parana Pine : Knot free, easy to work attractive yellow/red colour.

Western Red Cedar : Low strength but superb outdoor timber.

Yew : More like a hardwood, very hard attractive red timber. A strong resilient but expensive timber.

In What Forms is wood available ?

	Planks are the largest forms they are over 40 mm thick
	Boards are thinner than 40 mm and wider than 75 mm
	Strips are narrower than 75 mm
	Squares are square sections of various sizes.
	Veneers are thin slices of wood often used to decorate other wood.

Wood sizes will differ from dealer to dealer for more information look at suppliers catalogues. It is important to remember that unless they specify otherwise suppliers will quote only rough sawn sizes and prices.

PAR prefixing a price means 'Planed all round'

Deciduos hardwoods : These trees lose their leaves in winter. They grow in the warm temperate climates of Britain, Europe, New Zealand, Chile and Central USA. Common examples include: Oak, Ash, Elm,Beech, Birch, Chesnut, Lime, Sycamore, Walnut, Apple and Pear.

Evergreen hardwoods : These trees keep their leaves all year round, and therefore grow more quickly and to a greater size. They are usually softer and easier to work than deciduos hardwoods. They grow mainly in tropical or subtropical climates such as South Americal, Central America, Indonesea, Africa, Burma, East and West Indies. Common examples are : Mahogony, Teak, African Walnut, Afromosia, Iroko, Rosewood, Ebony, Balsa and Sapele, Jelutong.

Man made Boards

Available in very large sizes, 2440 x 1220 mm. They are very stable, flat, equally strong in both directions. Less expensive than using solid timber:

Blockboard : Smooth veneer finish, flat stable board, needs edging.

Chipboard : Inexpensive, good sound insulation, needs an applied surface finish. Can be very presentable when suitably finished.

Hardboard : Inexpensive thin board, very smooth hard surface.

Medium Density Fibre Board : Finer than chipboard or hardboard, good for small models.

Plywood : Available in many grades, interior, marine ply, etc. Thin sheets are flexible - thicker ones are much stiffer and stronger. Attractive when varnished.

Plywood is made from layers of veneer glued one on top of the other. The grain of each layer is at right angles to the one above to resist movement and improve strength. There are different grades, external grade "marine ply" is waterproof, general purpose plywood is for interior use only. Thicknesses range from 1.5 mm to 25 mm

Blockboard or laminboard is made from a sandwich of thin plywood and strips of softwood. It is expensive but strong and stable. The most common thickness is 18 mm

Chipboard is made of ground up particles of wood glued together and pressed into sheets. When dry it is stable, but breaks down easily when wet. Although not as strong as plywood or blockboard, it is popular because it is cheap. Chipboard is available covered with a veneer of wood, plastic or printed paper.

Hardboard is an inexpensive board made from compressed wood fibres glued in thin sheet form. It is normally used to cover frames cheaply and has one smooth hard surface, the other being textured and rough.

Medium Density Fibre Board or M.D.F. is made from much finer fibres than either chipboard or hardboard and has a smooth hard finish on both top and bottom surfaces. It is available in a variety of thicknesses.