Seasoning of Timber. 



can say without hesitation that exposure to the wind and air 

 brings about changes in the wood which are of such a nature 

 that the wood becomes drier and more permeable. When sea- 

 soned by exposure to superheated steam, similar changes ma)* 

 take place. The water leaves the wood in the form of steam, 

 while the organic compounds in the walls probably coagulate or 

 disintegrate under the high temperature. 



The relative ease with which so-called high and low grade 

 timbers can be treated is another matter to which attention is 

 called in this report. As a rule, high-grade timbers — Long- 

 leaf Pine or White Oak, for instance — are very much denser than 

 the lower grades, such as Loblolly Pine or Red Oak. The latter 

 usually have a higher percentage of sap wood, which can be 

 penetrated by a fluid very much more readily than heartwood. 

 On account of this greater porosity it is very much more 

 economical to treat a porous wood thoroughly with a good pre- 

 servative than to treat a more expensive denser wood with a 

 cheaper preservative. The cheap and porous wood well treated 

 will outlast the other in even* instance. 



One of the first steps in the process of making short-lived 

 timbers fit for treatment consists in a proper seasoning. More 

 benefit will result from taking care of the short-lived timbers 

 than from similar treatment of those with longer life. The 

 former are frequently short-lived because of their greater 

 porosity, which may mean a higher water content, and which 

 always means a greater power of absorbing and holding water 

 or any other fluid. The economical substitution of cheap for 

 high-priced timbers is impossible without proper seasoning. 

 The loss from the shortened term of service of unseasoned 

 timber is very much greater in the case of porous than of the 

 denser kinds, which are much less permeable to water, and con- 

 sequently offer greater resistance to decay. Susceptibility to 

 decay in timber is a consequence of relatively high porosity, 

 which may mean a high water content, and always means a 

 greater absorptive power, and a large percentage of sapwood, 

 w*hich furnishes, by its stores of organic matter, food for wood- 

 destroying fungi. Seasoning greatly lengthens its life, because 

 it rids it as far as possible of its water and brings about a dis- 

 integration of much of the organic matter, in both ways lessen- 



