UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 607 
Contribution from the Forest Service 
HENRY S. GRAVES, Forester 
Washington, D. C. 
PROFESSIONAL PAPER 
June 7, 1918 
TESTS OF THE ABSORPTION AND PENETRATION OF COAL 
TAR AND CREOSOTE IN LONGLEAF PINE. 
By Clyde H. Teesdale, in charge, Section of Wood Preservation, and J. D. MacLean, 
Assistant Engineer in Forest Products. 
CONTENTS. 
Page. 
Introduction 1 
Materials used 2 
Effect on penetration of differences in the pre- 
servative 5 
Page. 
Tests of the effect of varying time, pressure, 
and temperature 12 
Summary 21 
Appendix 23 
INTRODUCTION. 
One of the most important questions in the preservative treat- 
ment of wood is the cost of the preservative. Particularly is this 
true when creosote is used, and anything which will tend to reduce 
the cost of this preservative without decreasing its efficiency will 
be a direct aid to the industry. The use of tar and creosote mix- 
tures in the preservative treatment of wood has increased rapidly in 
recent years, particularly in the treatment of wood paving blocks. 
This is due largely to the fact that the tar and creosote mixtures 
can be produced more cheaply than can creosote containing no tar. 
There are two other factors, however, aside from cost which must be 
considered as affecting the use of tar and creosote mixtures. A 
preservative treatment, to be effective, should show good absorption 
and penetration and the preservative must be toxic to wood-destroy- 
ing fungi. 1 
This paper reports the results of an investigation into the effect 
of tar in creosote upon absorption and penetration of the preservative. 
The study was made at the Forest Products Laboratory, maintained 
by the Forest Service, United States Department of Agriculture, in 
cooperation with the University of Wisconsin at Madison, Wis. 2 
1 In general the toxicity of tar and creosote mixtures is sufficient to warrant their use in preserva- 
tives. Toxicity of wood preservatives is discussed in Bulletins 155 and 227 of the Department of 
Agriculture. 
2 Acknowledgments are made to Mr. F. M. Bond, formerly of the Forest Service, under whose 
direction a portion of this work was done. 
11917°— 18— Bull. 607 1 
