Contribution from the Forest Service, Henry S. Graves, Forester. 

 September 25, 1914. 



(PROFESSIONAL PAPER.) 



RELATIVE RESISTANCE OF VARIOUS CONIFERS TO 

 INJECTION WITH CREOSOTE. 



By C. H. Teesdale, 

 Engineer in Forest Products, Forest Products Laboratory. 



PURPOSE OF THE EXPERIMENTS. 



It is very difficult and sometimes apparently impossible to secure 

 uniform treatments of wood with preservatives. If, for example, an 

 average treatment is given of 10 pounds of creosote per cubic foot, 

 some pieces of wood in a charge will receive twice the average 

 amount, while others will receive less than one-half of it. Efficient 

 use of the preservative obviously requires that each timber receive its 

 full portion and no more. One essential condition for securing uni- 

 formity of treatment is that all pieces in any one charge shall present 

 equal resistance to injection. This requires that the wood be graded 

 in accordance with its ease of treatment, and the experiments here 

 described were made to investigate this subject. To obtain a logical 

 basis for such classification it was necessary to study the relation be- 

 tween the structure of wood and the manner in which it receives treat- 

 ments. This study was carried out at the Forest Products Labora- 

 tory maintained in cooperation with the University of Wisconsin, 

 at Madison, Wis. The present publication is confined to coniferous 

 woods. 



STRUCTURE OF THE CONIFERS. 



The woods of cone-bearing trees, or conifers, have certain similari- 

 ties of structure which distinguish them from the woods of broad- 

 leaved trees. In commerce the terms " softwoods " and " hardwoods " 

 are applied respectively to these two classes of wood. The follow- 

 ing description of wood structure applies only to the conifers. 

 1 , 



Note. — The purpose of this bulletin is to show how woods should be graded in order 

 that they may give uniform results when subjected to treatment with preservatives ; it 

 is intended for those interested in wood preservation. 



41702°— Bull. 101—14 1 



