WOOD PRESERVATION - TIMBER AND LUMBER Some kinds of timber rot quickly after cutting; others last for many years, even under severe conditions. No hard and fast line can be drawn between woods which are durable and those which are not, since much depends upon the proportions of sapwood and heartwood, the amount of seasoning, and the situation in which the timber is used. Neither is it possible to say that any one kind of timber is superior to all other kinds in durability, or that the softwoods as a group resist decay better than the hardwoods; or vice versa.
Among the woods which are generally recognized as possessing much natural durability, are the cedars, redwood, cypress, osage orange, and black locust. Posts, poles, and ties made of these woods are often sound after many years of service under conditions favorable to decay. On the other hand, timber of naturally durable woods which is not seasoned before it is used, or which contains a very large amount of sapwood, may rot quickly; while properly handled. timber of the less durable woods may last a long time.
Timber like maple, gum, or birch rots quickly if used for a post or railroad tie without preservative treatment, while, if seasoned and used for house finish, it lasts indefinitely.