A Laboratory Evaluation of Wood Preservatives 



By R. E. WATERMAN, JOHN LEUTRITZ and CALEB M. HILL 



Evolution of a simple laboratory technique for the assay of 

 materials proposed for use in the preservation of wood is reported 

 in this paper. This test involves a measurement of the actual 

 decay resistance of the treated wood. Included are a resume of 

 the limitations imposed by current test-methods and a discussion 

 of the adaptations of this new technique to the numerous variables 

 inherent in laboratory simulations of outdoor exposure. 



TTUNDAMENTAL scientific discoveries in the biological sciences 

 -*- during the latter part of the nineteenth century slowly brought 

 organized knowledge out of the chaos of conflicting theories as to the 

 character of many natural phenomena. This was especially true in 

 the field of fermentation where these accumulated findings and observa- 

 tions finally served as the basis for the proof that the filamentous 

 fungi were the causal agents in the decay of wood. This knowledge 

 of the decay mechanism, together with increased demand for wood 

 products due to industrial expansion and the concomitant depletion of 

 our best stands of naturally rot-resistant species of timber, served as a 

 stimulus towards organized studies of the physiology of decay or- 

 ganisms and possible means of prophylaxis. 



While Nature has been lavish in the supply of fast-growing species, 

 she has also been provident in making such timber more vulnerable to 

 attack by the micro-flora and fauna which act as scavengers for the 

 forests and as conservators for vast quantities of materials which trees 

 take from the soil during their growth period. The necessity of 

 preserving this more easily decayed wood accelerated the search for 

 satisfactory means of protection. This has been especially true in 

 the Bell System where fast-growing but easily rotted southern pine has, 

 to a large extent, been supplanting chestnut and cedar for poles. 



In the past the use of certain materials for the preservation of 

 wood was based entirely on their availability or the personal prejudice 

 of proponents for them. This method of selection could result only in 

 widespread waste and oftentimes disastrous consequences, but a wood- 

 preserving industry utilizing certain materials such as coal-tar creosote 

 gradually evolved. The controversies as to what properties of 

 creosote make it an effective preservative still rage, and the problem of 

 choosing and specifying the type of creosote best fitted for the preserva- 



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