i6 



HARDWOOD RECORD 



of the United States is now produced in the South. Another impor- 

 tant matter which might escape notice on first reading, is the show- 

 ing made by Ohio, Indiana, and Illinois. Those highly developed 

 agricultural states are actually increasing their output of lumber. 

 They passed the point years ago where they were properly regarded 

 as lumber regions; yet they have gone on producing lumber in large 

 amounts, and the later figures show a slight inc^ase. Some small 

 tracts of original forest remain in those states and are being drawn 

 upon by the mills, but there can be no question that most of the 

 present cut comes from woodlot timber that has made its chief gi'owth 

 since the region was settled. That seems to imply that those states 

 are now growing timber .is fast as it is being cut. If that conclu- 

 sion is correct, they can maintain their present lumber output — 

 about 1,000,000,000 feet annually-rfor all time. 



Their woodlots are valuable and are being protected from fire and 

 other injury, and a conservative estimate will place the yearly 

 growth of wood at 300 feet, board measure, for each acre. An 

 aggregate wooded area of 3,500,000 acres suffices to produce a 

 yearly cost of 1,000,000,000 feet. That is the end and aim of 

 forestry, and apparently Ohio, Indiana, and Illinois are getting 

 close to it. To maintain the present production of lumber they will 

 need to keep only one acre in woods to twenty-five in farm crops 

 and other uses. To increase the output of lumber it would.be neces- 

 sary to increase the wooded area, or improve the condition of exist- 

 ing woodlots. Those states ought to have one acre in woods to five 

 in farmland. If they should maintain that ratio, and obtain mod- 

 erate production from the woodlots, they might cut 5,000,000,000 

 feet .yearly on a pernuinent basis. The practical jn-oblems of forestry 

 are being worked out there. 



The Real Problem in Wood Seasoning 



HUNDREDS OF MEN are at work every day trying to solve the 

 problems of seasoning lumber. There are a number of problems, 

 some of which have been mastered, others are partly understood, while 

 along certain lines investigators are feeling their way with more or 

 less promise of final success. 



It is not a <lillicult matter to reduce green wood to a state of satis- 

 factory dryness, but that is one of the easy problems. The hard 

 part is to keep the wood in that state after it is further manufactured 

 into commodities. Those who have studied tlie matter of seasoning 

 have frequently confined their efforts to the mere process of drying 

 the weed. That is really no j)roblem at all, where time is not impor- 

 tant, for lumber left in the open air a sufiicient period — weeks, 

 months, or years — will season to a large extent, and a brief time in 

 a kiln wiU complete the ]iroecss. But the work stops at the very 

 point where something further is necessary; because kiln-dried wood 

 will not remain long in that state. It will begin to pick up moisture 

 from the air as soon as the artificial heat is removed, absorbing damp- 

 ness when the air is moist, and parting with some of it again when 

 the atmosphere becomes dryer. This indicates what the real problem 

 is^to season wood and keep it seasoned. 



Ordinary green timber may be half water, a little more or a little 

 less. In reducing the wood to a dry state nearly as much weight 

 disappears as remains. Two formulas are in use to express the 

 (juantity of moisture in wood. One takes the timber's green weight 

 as the basis, the other the dry weight. In the first place the water 

 may equal fifty per cent of the green weight ; in the second, one 

 hundred per cent of the dry weight. The facts are the same; the 

 difference is in expressing them. It is preferable to use the dry 

 weight as the basis for exj)ressing the moisture of wood in per- 

 centages. 



• Thoroughly air dried wood contiiins from six to as high as sixteen 

 per cent of water, based on dry weight, or from three to eight per 

 CQnt- based on green weight. It is difficult to reduce this moisture 

 lower by air-seasoning, because if the wood parts with a little of it 

 ,wheu conditions are favorable, it is sure to pick it up again from 

 lh« air in a short time when conditions become unfavorable. 



The heat of the drykiln reduces the moisture still lower. At IJl'J 

 degrees, the temperature of boiling water, the moisture may be run 

 dow.n to two or three per cent of dry weight, but there that jirocess 



stops. In order to expell the residue of the water, the temperature 

 must be raised to a point sufficient to destroy the wood. That mat- 

 ter need not be considered in timber drying, because it is of no 

 interest to the wood worker and passes over to the province of the 

 distillation plant. 



The wood worker, says the furniture maker, takes his kiln-dried 

 lumber with moisture down to three or four per cent, or less, and 

 his troubles begin. The wood presently begins to absorb water from 

 the air, and iu time returns to the air-dry condition. The moisture 

 expelled by the kiln's heat gets back again. If the lumber would 

 remain in one condition, even if not very dry, the problem of handling 

 it would be simple; but it will not do that. Every change in atmos- 

 pheric temperature and humidity varies the amount of water in the 

 wood, and that is what causes the trouble. 



jSTo fact is better known than that wood shrinks and swells as it 

 parts with or absorbs moisture. If it is manufactured into furniture 

 when quite dry and afterwards absorbs water, swelling ensues, with 

 the result that drawers become tight and doors open and shut with 

 difficulty; but if it is made up while moist, subsequent shrinkage 

 in a dry climate or a hot room will pull the joints apart. 



This condition brings the manufacturer face to face with a prac- 

 tical and difficult problem — what can be done to lessen the shrinkage 

 and swelling of wood? If it could be prevented from taking up 

 moisture from the air, or parting with it, one of the wood worker's 

 most perplexing problems would be solved. But wood does take up 

 and ])art with water and that fact is at the root of the trouble. 



Solutions and ameliorations of the difficulty are being sought 

 along various lines and in many ways, and encouraging results have 

 be'?n reached. The wagon maker covers his wheels with heavy paints 

 well rubbed iu. That seals the pores of the wood and the moisture 

 is mateiiallj' hindered or totally prevented from entering or escaji- 

 ing. Shrinking and swelling are reduced in proportion to the com- 

 ])lcteness of the sealing process. The maker of bicycle rims boils or 

 soaks his wood in oil with the .same result. The furniture manufac- 

 turer uses oils, fillers, ))aints, shellacs, .and varnishes to seal the 

 wood pores to hold the moisture already within and jirevent shrink- 

 age, and to shut out other moisture to guard against swelling. 



They have the correct i)rinciple, but methods have not yet been 

 jierfected. Covering the surface with moisture-proof materials is 

 still in the experimental stage. Much progress has been made, but 

 the end has not been wholly attained. 



Experimenting along other lines has brought results which hold 

 out promise of great success. The effect of forcing superheated 

 steam into and through the pores and cell structure of wood has 

 op'.ned a new field of investigation. It has been shown that wood 

 so treated has its tendency to shrink and swell much reduced, and it 

 is supposed that the action of the hot steam changes in some way 

 the character of the cells or wood fibers, with the result that water is 

 less readily absorbed. This is not new theorj- or new practice. 

 Wood technologists are well acquainted with the effect. Record 

 says in his book, "Economic Woods of the United States," page 59: 

 ■ ' Hygroscopicity [tendency to absorb nuiisture] can be reduced, but 

 not entirely eliminated, by subjecting wood to boiling, steaming. 

 ]irolonged soaking, or exposure to high temperature." 



.lust why steaming has that effect is not well understood. If the 

 su[ierheated steam is applied within moderate limits it not only 

 lessens wood's tendency to absorb molstilre, but apjiarently increase.-; 

 its strength. This result may be due to the rapid drying and harden- 

 ing of the individual fibers — case-hardening the wood cells themselves, 

 so to speak. Theoretically, that ought to rcdu<'e the hygroscopicity 

 of the fibers themselves, and if it does th.at, the cause of the dimin- 

 ished tendency to shrink and swell is not difficult to explain. 



Much of this is theory as yet, because the exact nature of the 

 change which takes place in the minute structure of the wood ha." 

 not been determined. The cause is less important than the effect. 

 -Any process or agency that will diminish the influence of atmospheric 

 moisture on wood, thereby reducing shrinkage and swelling, is a con- 

 trilmtion to the science of lumber seasoning. The steamed ox bo«, 

 the steamed drum shell, the steamed grip of the plow handle, never 

 ihnnge their form afterwards thmigli I'Xposcd to rain and sun for 



