COATINGS FOR WOOD. 179 



It will then season more quickly and be more durable than when 

 dried without soaking. Sometimes it is absolutely necessary to 

 thus water season large timbers, as it is impossible to get the sap 

 out of them by atmospheric seasoning. Large checks or cracks 

 in the ends of logs or other timber of large dimension may be 

 avoided or greatly lessened by painting the ends with linseed oil 

 mixed with ground charcoal or other material to give it con- 

 sistency. Covering with cloth or tarred paper also lessens check- 

 ing. 



Good Coatings for Wood consist of oily or resinous 

 substances that are easily applied in a smooth coat and dry 

 readily, yet do not have any tendency to crack or peel off. They 

 should be applied to the whole exposed surface. 



Coal Tar is one of the best materials for covering wood to 

 increase its durability. It is best applied hot, especially if mixed 

 with oil of turpentine, as it then penetrates more deeply. A 

 mixture of three parts coal tar and one part unsalted grease, to 

 prevent the tar from drying too quickly so it may penetrate the 

 wood better, is recommended. One barrel of coal tar will cover 

 from two to three hundred posts if it is properly applied. 



Oil Paints are next in value. Boiled linseed oil is used 

 with lead, pulverized charcoal, or other similar material, to give 

 it substance. Soaking the dry wood in crude petroleum is also 

 recommended. 



I/ime Whitewash is a good preventive of decay in wood 

 and, although not as good for this purpose as coal tar, it is very 

 desirable. As with all other preservatives that are applied to the 

 surface, the wood should be very dry before it is applied, and 

 the wash should be applied evenly over all the exposed parts. It 

 is on account of the lime that washes out of the mortar that the 

 shingles on a roof just below the chimney last longer than on 

 other parts of the roof. But if whitewash is to be applied to 

 shingles it should be applied before they are laid by dipping. 



Charring those parts of posts or timbers which come in 

 contact with the ground is a good preventive, provided a thick 

 layer of charcoal is formed and the work so carefully done as not 

 to cause the timber to crack, since deep cracking exposes the 

 interior to decay. If not carefully done the timber may be 

 seriously weakened. 



