126 



THE SAWMILL 



The air in the dry kiln must be kept in constant motion, so as to prevent the lumber in the piles 

 from drying unequally. 



Lumber can be more evenly dried by steam than by hot air. 



Sap water converted into steam expands 1,670 times. Consequently, wood kept at 212 degrees would 

 retain only a small portion of the water originally contained in it. In the dry kiln, the temperature is 

 raised slowly to 160 degrees. It should never be allowed to reach steam heat. 



No two dry kilns are absolutely alike in the proper method of handling, in the manner in which the 

 temperature should be guided, and in their efficiency under seemingly identical conditions. The effect of 

 a dry kiln depends on its geographic location, and also on the weather of the four seasons of the year. 

 Each kind and each thickness of lumber requires a special study. The moisture of the lumber itself, as 

 it goes to the kiln, must be carefully considered. The foreman in charge of a new kiln must become 

 acquainted with it, by watching it carefully and conscientiously, before the best results can be obtained. 

 Nothing must be left to haphazard. 



Leading manufacturers of dry kilns are the Standard Dry Kiln Co., Indianapolis. Ind.; the Grand Rapids 

 Veneer Co., Grand Rapids, Mich.; the National Dry Kiln Co., Indianapolis, Ind.; and B. F. Sturtevant & Co., 

 Hyde Park, Mass. 



Dry kiln cars automatically stacked by stacker of North Coast Dry Kiln Company, 



Seattle, Wash. 



Quite recently, successful experiments have been made with the "preparation" of lumber prior to 

 kiln drying. 



The Kraetzer steam cylinder preparator, manufactured by the Kraetzer Company, 537, South Dearborn St., 

 Chicago, III, consists of a horizontal steel cylinder that can be sealed hermetically with great ease and 

 into which the lumber, loaded on small cars, is placed. In lieu of stickers, wire screen is used. 



The lumber is placed into this steam cylinder green from the mill. 



Live steam is admitted, under pressure, for a number of minutes. The Kraetzer preparator is not a 

 dry kiln. It shortens, however, the dry kiln process. It prevents staining, checking, and end-splitting; it 

 secures, after kiln drying, a reduced weight in the luinber. 



An automatic stacker for lumber going into the dry kiln is used largely in the South and also in the 

 West. The lumber is delivered to the stacker on endless rolls and is placed, not horizontally but vertically 

 onto the dry kiln cars. Similarly, an automatic unloader for dry kiln cars is being used, the lumber being 

 taken up by the welds of endless chains, automatically, tier after tier. 



