September 10, 1921 



HARDWOOD RECORD 



19 



The Manufacture and Seasoning of Oak 



By David G. White, Forest Examiner, U. S. Forest Service 



'Seasoning of Oak 



Oak uiay bo air seasoncii or kiln dried, depending upon suili 

 factors as local facilities, speed of production required, and the 

 final moisture content to vvliich the material must be dried. 



AIK SEASONING: Stock to be air dried should be piled in uni- 

 form lengths and widths. I'lenty of circulation should bo provided 

 by piling on foundations largely open at the sides and front and 

 rear ends. Upward ventilation is provided for by leaving a space 

 between the edges of the boards and by the use of stickers between 



F. P. L. DRYING SCHEDULE 6 



Applies to 4 4 to 6/4 inch Northern Red and White Oak, excepting lumber with 



wide annual-growth rings, which should be dried according to Schedule 7 



Uolstur* 



• oatnt of 



tb« taood »t 



▼arlotts 



■t*g*a of 



la p«r otot 

 of orj 

 ■•Ifkt 



Boalllt/ IDA t*ap«r>tuj'« 



of air •Dtarlng pll* %\ 41f- 



t9T%a\ BOLaturo ooataats 



of th« lood 



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ulal 



ralatlTai- 

 husldlt/ [ 



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: Daw 

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Approzlaate iiujabtr of 

 daya to ary ona-looh 

 pLaln^aaftad atook to 6 

 par ooQt molature, 

 aturtii« from dlffaraat 

 noidtura oontoota of 

 xht »ood. ( nartar 

 aaaad laJLaa ateut 1/S 

 longar) . 



60 



te 



ao 



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lie 

 lie 



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 1 109 



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 : 107 



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 £T 



86 

 36 



the layers or courses. The stickers should be of seasoned heart- 

 wood, free from decay, and of uniform thickness, and should be 

 placed flush with the ends of the boards, about 2% feet apart for 

 lumber up to and including 2-inch stock, and 3 feet apart for thicker 

 lumber. The stickers should be about 1 inch thick for 1-ineh 

 stock, 1% to 2 inches for 2-inch stock, and 2 to 3 inches for 

 thicker stock. 



The piles should not be less than 2 feet and preferably 5 feet 

 apart. They should have a forward pitch of about fj of an inch 

 per course. Piles of high-grade lumber should have the ends jiro- 

 tected from the sun 's rays liy paint, upright sun shields of lumber, 

 etc. The height of the piles depends upon such factors as the thick- 

 ness of the material, method of piling, yard space, and width of 

 pile. In hand piling the length of the lumber largely governs the 

 height, somewhat as follows: 



4/4 inch thick 12 feet long — 70 to 7-> courses high. 



4/4 inch thick 14 feet long— 75 to 80 courses high. 



4/4 inch thick 16 feet long — 80 to 8.5 courses high. 



5/4 inch thick 12 feet long — 60 to 65 courses high. 



5/4 inch thick 14 feet long — 65 to 70 courses high. 



5/4 inch thick 16 feet long — 70 to 75 courses high. 



•Secona installiiient "f article, first of which appenrod In August 

 issue. First section disiiissi'il Manufacture of Oak. — Kdltor. 



(i/4 inch thick 12 feet long — 50 to 55 courses high. 



6/4 inch thick 14 feet long — 55 to 60 courses high. 



6/4 inch thick 16 feet long — 60 to 65 courses high. 



8/4. inch thick 12 feet long — 40 to 45 courses high. 



8/4 inch thick 14 & l(i feet long — 45 to 50 courses high. 



The lumber should slope about one inch to the foot and should 

 have a covering raised up several inches above the lumber and 

 protruding several inches beyoml each end of the pile. 



Kiln Drying 



In kiln drying the lumber should be carefully piled, using stick- 

 ers as in air seasoning. The original and final moisture content of 

 the material and the size of the pieces largely determine the length 

 of the seasoning period and the temperature and humidity condi- 

 tions to which the material should be subjected. 



A number of kiln-drying schedules have been workeil out at the 

 Forest Products Laboratory, suitable for oak used in the manu- 

 facture of furniture and similar products, where the maximum 

 strength of the wood is of secondary consideration. Oak for uses 

 having less exacting requirements than use for furniture can prob- 

 ably be dried a little more rapidly than indicated in the schedule 

 according to which it would be dried for furniture. The schedules 

 should be suitable for any kiln in which the circulation is positive, 

 ample, and uniform in all parts of the kiln and in which the humid- 

 ity and temperature can be correctly measured and accurately con- 

 trolled. The conditions specified in the schedule api)ly to the 

 warmest point in the kiln, and thermometers and moisture samples 

 should be so placed that the drying conditions and rate of drying 

 at that point may be known at all times. The wet-bulb and dew- 

 point temperatures are given in columns 4 and 5, for the corre- 

 sponding humidities given in column 2, at the temperature specified 

 in column 3. The wet-bulb temperature is used in determining the 

 humidity in the kiln with a hygrometer, and is slightly higher than 

 the dew-point temperature, which is used in determining the huinid- 



F. P. L. DRYING SCHEDULE 7 

 Applies to 4 4 to 6 4 inch Northern Red and White Oak having wide annual- 

 growth rings and Southern Red and White Oak having narrow to medium 

 width growth rings 



Holatnra 



aonsit of 



tha wood at 



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 tha voo4 



I 



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Taaparatara 



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 1 balki taU I point 

 : I I : 



lApproxlaata nuabar of da^a 

 ito drr ooa-laab plaln- 

 laawad atoak to I par a«it 



:aolBtar«. atarttag Croa 

 •dlffaraot aolatura aoo- 

 itaota o f tha wood . f Qaartar 

 laaaad taiaa akont l/t 

 :longar) . 



to 



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 tt 



to 



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se : 110 I 104 : lot 



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41 



40 



10 

 16 



10 

 6 



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86 I 140 : 



