Factors affecting the durability of Oak

Oak is best on soils where it is the longest in coming to maturity. When two specimens are equally seasoned, their value may be ascertained by trying which, bulk for bulk, is the heavier, or by soaking them in water until they can contain no more. The one which has its weight least increased is the best.

If an oak be dead at the main top, the centre of the tree is sure to be eaither in a state of decay or about to decay, and it is not safe to use any part of it for purposes where strength or durability is required.

The same holds true of all deciduous trees. Evergreens are not so liable to be hollow.

An oak, or almost any other tree that grows singly, or on the outside of the forest, is always more firm and durable than one which grows within the forest and which is partially sheltered. Also the more variable the climate, the firmer and more durable the timber. An oak which stands alone on a hill side, exposed to the variable weather of Britain, will, as timber, outlast two from the thick forests of Germany, or three from North America, where the summer is intensely hot, and without a cloud for many weeks together.

Trees which are to be used as timber should be felled in the early part of the winter when the sap is at rest. When the sap is in motion, the trees tend to bleed, and the durability of the timber is diminished. This apples to pines as well as deciduous trees.

Oak grown in damp situations decays much sooner than that which grows on dry, and the decay is from the outside to the centre. This is for timber which has been felled before beginning to decay. (if rot has begun before felling, the timber rots first at the centre.)

Oak is best seasoned in water and air alternately, taking care not to dry it in the sun; this would cause it to champ and split. A large beam of oak ought to soak for at least 12 months, but half that time will do for planks.

It is often the practice to season planks by boiling and steaming. This sometimes has to be done, as for the bows of a ship, but it weakens the timber.

summarised from "The Library of Entertaining Knowledge - Timber trees" (1829), pub. Charles Knight, Pall Mall.

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