HOW WOOD IS PRESERVED 149 
decay above the ground level but just at the point where 
they enter the ground they become soaked with moisture 
and rapid decay takes place. Wood when used green and 
full of sap is extremely inviting to fungi because in addi- 
tion to moisture the sap contains starches and sugars 
which supply the agencies of decay with plenty of food 
for their development. The seasoning of timber not only 
adds greatly to its durability but also increases its 
strength to a marked degree. 
In some cases timber is allowed to season in the log 
but as a rule, seasoning in the round is due to an over- 
supply of logs rather than to intention. When logs 
have been sawed into planks greater surface is exposed 
to the air and consequently the seasoning process is 
more rapid. The change in strength and durability 
after seasoning is not alone due to the loss of a certain 
amount of water but in addition there are certain 
changes in the cell walls. 
The seasoning of lumber is an extremely important 
part in its manufacture and sawmill men select the 
location for their mill with great care. Timber may 
be ruined by poor seasoning or at least the grade of 
the material may be lowered, thereby decreasing its 
value. If the mill site has been unwisely chosen so 
that free circulation of air is impossible, material may 
season very poorly and a fungus growth like “blue 
stain” will be extremely common with certain species 
which will spoil the appearance of the valuable grades. 
The length of time which timber is allowed to season 
in the pile depends much upon the species. Conifers 
will be well seasoned in from three to six months while 
hardwoods require close to a year for perfect seasoning. 
Manufacturers very often will ship lumber before it is 
wholly seasoned for by removing a part of the water 
