248 The Farm Woodlot 



Charring 



Charring is a very good method of protecting those 

 timbers which come in contact with the ground. The 

 carbonization of the exterior of the wood forms a coating 

 impervious to the fungus attacks. It also serves to 

 harden the wood. It must, however, be very carefully 

 applied. A rather thick layer of charcoal must be formed 

 over the entire exposed surface, but at the same time the 

 timber must not crack. A crack either exposes the 

 interior to rot or allows the fire to burn in so deep that the 

 strength of the timber is seriously impaired. The process 

 should not be applied to any timbers on whose strength 

 dependence is placed. It is only suitable for posts and 

 poles. 



A very effective way to char posts is to dip them in tar 

 or, better yet, crude petroleum, and burn off the coating. 

 This chars the posts evenly and drives some of the oil into 

 the wood. Some experiments have shown that posts 

 treated in this way have tested very well in comparison 

 with posts treated with creosote. 



GENERAL RULES ON PRESERVING TIMBERS 



All timbers should be thoroughly peeled, both outer 

 and inner bark, before treatment. Bark prevents season- 

 ing, prevents the preservative from sinking into the wood 

 and itself absorbs preservative which will not increase the 

 durability of the wood. 



Sap wood is much more easily treated than heart wood, 

 in fact the penetration of the liquid practically ceases when 

 the heartwood is reached, unless some special provision is 



