THE PRESERVATIVE TREATMENT OF POLES 



BROR L. GRONDAL, '12 

 Assistant Professor of Forestry. 



USERS of poles have gradually come to a final realization of the fact 

 that the economy resulting from the butt treatment of poles with 

 creosote is so great that in nearly all cases such treatment is 

 advantageous, despite the fact that untreated western red cedar 

 poles are normally very long lived. At a perfunctory glance, it would seem 

 that an additional cost of a dollar and more per pole for creosoting would 

 be prohibitive, regardless of the fact that such a treatment will prolong 

 the life of the pole as much as five to ten years. If the cost of replacing 

 poles is taken into consideration, the economy of such treatment becomes 

 vividly apparent. In many cases the replacement of a single pole means 

 the expenditure of from $30 to $40, and even much more. Compound 

 interest on the cost of replacement for ten years may in some cases mount 

 to as much as fifty times the cost of creosoting. 



No argument for the treatment of poles, especially those used for 

 carrying electrical equipment, is needed at the present time, for the pole 

 treating plants on the Pacific Coast are already overcrowded with work, 

 though severa} new plants have recently been built and several more 

 projected. Indications are that in the future practically all poles for 

 electrical work will be treated in some manner to make them more resistant 

 toward decay. 



Decay in western red cedar poles always originates at the ground line. 

 This is due to the fact that conditions for decay are at an optimum at this 

 point. In order to be active, wood-destroying fungi must have a certain 

 amount of heat, air, moisture and food. The presence of any one of these 

 requirements in minimo regulates the total development of a fungus. It 

 is quite apparent to even a casual observer that heat and moisture will be 

 available to the fungus in the most favorable quantities near the ground 

 line. Above the ground line, though heat, air and food are present in 

 sufficient quantities, the development of a fungus proceeds more slowly, 

 for due to seasoning this portion of a pole usually contains a deficient 

 supply of moisture. Below the ground line, at a depth varying with soils 

 of different characteristics, the air supply is deficient, and the development 

 of a fungus can proceed only very slowly. 



It is therefore obvious that the portion of the pole that needs protec- 

 tion from fungi is the section immediately above and below the ground line. 

 (See first pole in illustration). This protection can be secured either by 

 removing the air supply, the moisture supply or the food supply. Exper- 

 ience has indicated that it is not commercially practicable to treat a pole 

 at the ground line so that the air or moisture supply is reduced to a point 

 sufficiently low to inhibit the growth of a fungus. The one remaining 

 proposition, then, is the removal of the food supply. The food supply of 

 a wood-destroying fungus is, however, the wood itself. While some .mis- 

 guided enthusiasts wish to remove the food supply by substituting otherwise 

 inferior steel or concrete poles, such a proceedure is not justifiable or neces- 

 sary, for by the simple expedient of injecting creosote into the wood, the 

 food supply is poisoned and effectually removed from within reach of the 

 tungus. 



The application of creosote, which is a product obtained in the distil- 

 lation of coal tar, to the lower 6 to 10 feet of poles is usually accomplished 

 by a so-called "butt treatment" in an open tank. The poles are placed on 

 end in an open tank of steel, which is then filled with creosote so that the 



