Wood Type
Hardwood
The Tree
Both species reach a height of 18m to 30m or a little more depending upon growth conditions which also affect the length of the bole. When drawn up in forests at the expense of their branches, this may be 1 5m or so in length, but in open situations, the tree branches much lower down. Diameters are about 1.2m to 2m.
The Timber
There is no essential difference in the appearance of the wood of either species. The sapwood is 25mm to 50mm wide and lighter in colour than the heartwood which is yellowish-brown. Quarter-sawn surfaces show a distinct silver-grain figure due to the broad rays. The annual rings are clearly marked by alternating zones of early-wood consisting of large pores, and dense late-wood. Conditions of growth accordingly govern the character of the wood to a great extent; for example, in slowly grown wood the proportion of dense late-wood is reduced in each annual growth-ring, thus tending to make the wood soft and light in weight. The growth conditions in the various countries which export oak, vary considerably. The weight of oak varies according to type; that from the Baltic area, western Europe, and Great Britain being about 720 kg/m³ and that from Central Europe about 672 kg/m³ on average after drying.
Drying
Oak dries very slowly with a marked tendency to split and check, particularly in the early stages of drying, and there is considerable risk of honeycombing if the drying is forced, especially in thick sizes. End and top protection must be provided to freshly sawn stock exposed to sun and drying winds and sticker thickness should be reduced to about 12mm for stock piled in the open air during early spring and onwards until winter.
Working Qualities
Medium to difficult – The working and machining properties of oak vary with the mild to tough material which either machines easily or with moderate difficulty. In general oak finishes well from the planer or moulding machine although in some cases a reduction of cutting angle to 20° is preferable. The wood can be stained, polished, waxed, and glued satisfactorily, takes nails and screws well, except near edges, when the wood should be pre-bored, and takes liming and fuming treatments well.
Strength
Both the sessile and pedunculate oaks have well known and high strength properties, and those hybrid oaks developed from both types and common throughout Europe, are similar in their strength properties.
Treatability
Extremely difficult
Moisture Movement
Medium
Density
720kg/m3
Abrasions
Very Good
Texture
Medium to coarse
Chemical Properties
Iron staining may occur in damp conditions, similarly corrosion of metals.
Use(s)
Heavy structural use, Cladding, Joinery – Exterior, Joinery – Interior, Furniture, Flooring, Sleepers, Decking
Colour(s)
Yellow-brown
Sample
