30 DEPARTMENT BULLETIN 1425, U. S. DEPT. OF AGRICULTURE 
separated and facilitates air movement, the weight causes sag in the 
pile at this point and consequently a greater proportion of bowed 
stock. 
STOCK CROSSERS AND SPECIAL CROSSERS. 
Two general types of crossers are employed in air seasoning— 
stock crossers and special crossers. Stock crossers come into use when 
green stock is crossed with itself. Special crossers, as the name im- 
plies, are strips or thicker pieces used repeatedly upon any grade or 
size of green lumber. The size of stock crossers is, of course, auto- 
matically fixed by the dimensions of the stock piled. The special 
type, however, is usually 4 inches in width, although occasionally 6 
inches, and 1 or 2 inches thick. The use of stock for crossers permits 
rapid piling, increases the capacity of the piles, and eliminates the 
necessity of carrying a large amount of stock in the form of crossers. 
This practice, however, results in serious depreciation losses which are 
avoided in the use of special crossers. 
The stock crosser is subject to heavy degrade from season check 
and is also largely responsible for this defect in the piled lumber. 
Checks develop in those sections of the crosser which come between 
the tiers of stock, or, stated in another way, in the parts which he 
within the vertical fiues. At these points both faces are exposed to 
the air, and drying proceeds much more rapidly than in the adjacent 
sections which are covered, top and bottom, by the green stock. The 
resultant uneven shrinkage causes checking in the portions which 
dry quickly. (PI.6,B-land4.) A similar difference in drying rate 
between the crossed and uncrossed portions of the lumber causes like 
defect. In pine lumber conditions are highly favorable for blue-stain 
development in these extremely slow-drying intersections of the stock 
and crosser. The so-called “ crosser-stain” blemish is therefore a 
common result of self-crossing pine lumber. (PI. 6, B-2 and 3.) 
The wide green stock crosser at the front and rear of the pile also 
causes excessive end checking. This results from the very marked 
difference in drying rate directly at the ends of the stock and in the 
adjacent sections which are between the crossers. , 
These very objectionable results of air seasoning are greatly mini- 
mized through the use of the special crosser. Special crossers being 
narrower and usually air-dry, or partly so, have less tendency to 
check. Furthermore, stock of relatively low value can be utilized for 
this purpose. Air-dry, narrow crossers, if properly projected be- 
yond the ends of the stock, vary largely eliminate end checking. 
Not only are the conditions less favorable for stain development but 
the area affected is more restricted. 
The relative merits of these two methods of crossing Western soit- 
wood lumber have been thoroughly investigated by means of con- 
trolled yard tests in different regions and with several species. Com- 
mon pine in the Inland Empire seasoned in self-crossed piles showed 
depreciation which averaged 14 per cent greater than that in com- 
parable special crosser piles—4 per cent greater degrade in the piled 
stock and 10 per cent in the crossers. The actual loss per 1,000 feet 
of stock piled in drying No. 2 common pine was over $2 more in the 
stock-crosser piles and the drying rate was slower, the lumber requir- 
ing one to four weeks’ additional time to reach an average air-dry 

