LUMBER GRADES AND LOG GRADES 459 



tion, the grade designated as No. 3 Common may in certain regions contain unsound 

 material which would not be scaled on the basis of sound scale. Hence a portion of 

 the No. 3 grade, if so constituted, plus all of the cull grades of lumber, when utilized, 

 go to increase the amount of over-run secured in manufacture. 



From one to three grades of lumber below No. 3 Common may be recognized, 

 according to the species and region. 



Common Grades Culled in Sound Scale of Logs. Southern Yellow Pine. No. 4 

 Common boards shall include all pieces that fall below the grade of No. 3 Common, 

 excluding such pieces as will not be held in place by nailing, after wasting one-fourth 

 the length of the piece by cutting into two or three pieces; mill inspection to be 

 final. 



359. Log Grades. Determination. The purpose of denning log grades is to 

 furnish a basis for separating the logs into groups whose average value or price per 

 1000 board feet can be determined, instead of attempting to arrive at an average 

 price for the entire run of logs. Three such groups permit of a sufficient differentia- 

 tion for this purpose. 



Where logs are not bought or sold, but standing timber is manufactured by the 

 purchaser, log grades (§ 87) form the best basis for appraising the value of this timber. 



The specification for determining the grade of logs must apply to the external 

 appearance and dimensions of the log. In application, logs on the border line between 

 two grades are usually thrown to the grade below, since a part of the surface is invis- 

 ible. Log grades are based on 



1. Minimum diameters and lengths. 



2. Surface appearance, and presence of knots or visible defects. 



3. Judgment of scaler, based on 1 and 2 as to the minimum per cent of upper 



or better grades of lumber contained therein. 



The specifications for log grades are more elastic than for lumber grades, since 

 the presence of a small per cent of high grade lumber may serve to offset serious 

 defects and give the log the value of a grade from which it would be excluded if based 

 solely on quantity or scale. These specifications should be drawn in such a manner 

 as to furnish the most serviceable basis of subdivision of the existing range of quality 

 found for the species and region, which object may be secured by modifying the 

 requirements as to size and per cent of upper grades required for logs of first and- 

 second grades. 



Log grades should be established only after thorough mill-scale studies, and by 

 some agency similar to that of the United States Forest Service or a Lumber Manu- 

 facturers' Association, so as to secure uniformity over as wide an area as possible. 



Within the limits of a log grade a certain variation in average quality will occur 

 in different quantities of logs, owing to the preponderance of higher or lower grades 

 of lumber within the limits set. The quality of the logs which form the basis of the 

 mill-scale study may be better or poorer than the average, even after classification 

 into grades. But as logs and timber stumpage are worth considerably less than 

 lumber, it is unnecessary to attempt a greater refinement, nor could it be practically 

 applied. 



Diameter. For logs of the best grade, diameter is a reliable guide. Up to a 

 certain size, trees retain the branches, either alive or dead, and the central bole of 

 the tree is filled with these knots. Stunted, slow-growing, and consequently small 

 trees still have these knots, and during their growth, have made very little clear 

 lumber. Large trees, on the other hand, even if no older, have laid on much clear 

 wood outside of the knots. 



The minimum diameter for the highest grade can be fixed to include practically 



