26 



HARDWOOD RECORD 



September 10, 192-.' 



YARD AND KILN 



<lA Section Intended to Promote EfRdency^ 

 and Economy in Lumber Dicing ^ 



Hardwood and Softwood Drying Schedules 



Eleven kiln drying schedules which cover practically the entire 

 range of hardwood and softwood lumber drying have been prepared 

 by the U. S. Forest Products Laboratory, Madison, Wisconsin. 

 These schedules are based on the moisture content of the stock in 

 the kiln, which is the safest basis and the one which assures the 

 most uniform results. They are presented in two series, Nos. 1 to 

 8 being for hardwoods. The two series supplement each other, 

 and taken together form eleven steps from the most severe to the 

 mildest drying conditions recommended for general commercial 

 practice. No. 000 of the softwood schedules is the most severe, 

 and No. 8 of the hardwood schedules is the mildest. 



Following the schedules are lists of hardwood and softwood 

 species with an index of the schedules to be used in drying them. 

 The schedules indicated for the hardwood species are safe for dry- 

 ing lumber up to 6/4 inch thick. For each inch over 6/4 in thick- 

 ness a schedule one milder (numbered one higher) than the one 

 listed for the species should be used. The schedules to be followed 

 in drying different thicknesses of softwood lumber are listed in 

 the table. When it is necessary to dry at one time in the kiln two 

 or more kinds of lumber requiring different drying schedules, the 

 mildest of the schedules required should be followed. 



Perfect drying does not always result from merely following a 

 schedule, no matter how closely temperature and humidity condi 

 tions are made to conform to those specified. The operator must be 

 trained to watch the conditions of the stock in the kiln and tn 

 apply the proper remedy if things start to go wrong. 



HARDWOOD .SCHEDULES 1 TO 4 



■■.THph fiimisht'd hy Ihc T'. S, Fon-st Scnlcel 



Laboratory Engineer Making Chemical Smoke Test 



