Jaoimry SA, llilO 



K. C(iN.\. \AZou « rr\. MISS.. Willi 



TAI.KKII ON KKilKKIi Uicn iJI'M. 



w M.I I.I Ki;, Mi;Miiiis. Ti;xN,. Wlio 



TAI.KKK OX MAIlKKTlNii OF «IJM. 



TIIKMA.S \V. lUV. KT. I^il.18. MO.. 

 TIUSTKE. 



Ilni- winif plare belwepn wimt n pnrltculiir rnminodlty itbould fnlrl.v i-nn- 



'rtlMi* ' •• 'rit Is on umliii' i-ontriliiitluii. Tbc dctprminntlnn of n Juki 



■oil to he np|>ll<'il for n Riv.-n nervlcc on n clvi'ii comiiimllt.v 



'• "" lunt Interi'.st to ilio iimniifncturers nn<) sliippiTs of fn-l^ht. 



AnotluT thing slioiild be noti'il. Id those tla.vs when rotes wore ninrte li.v 

 private contract It will ho found that the lowest rate.s were nlwn.vs niiide 

 on goods niorlng In large voltiinc between large cominerclnl cenli^rs, hut 

 lumlMT cenerall.v Is distributed from the mill to the local yards and thence 

 'o " ■ r "o that when the torlC became the actual factor In detcr- 



•"1" I'll rate for the first time In lOOii, low rates were not pub- 



Ush.-.i ..1. nil r to represent the actual rates pold, as was the case on 



many other commndltl(*s. 



Proper Handling of Gum 



Janics E. Iinrie of tljo Forest Pro. In. is I.alioiatory, Madison, Wis., 

 nddressed the meeting on tlio proper handling of gum in air and kiin- 

 drying. He dcsoritied the microscoiiic structure of wood, and stated 

 that red and black gums are perhaps the simplest in structure of all 

 the hardwoods, and might be expected to offer little resistance to dry- 

 ing. His address follows in part: 



The problem of drying woods Is one that should be studied for each wood 

 separately, because the structures of dlHer^nt woods vary so creatly th.it 

 the method found best for one may not meet the requlreiiients of another. 

 Shrinkage depends largely upon the rate of drying, but not wholly. The 

 licst process for any wood Is found oy actual trial. Just how much the 

 shrinkage of gum Is influenced by the temperature and drying rate is not 

 known nt present, but there Is no question that the method of seasoning 

 affects the shinkage of the gums : however, it Is Just posslMe that these 

 woods may shrink longitudinally more than normal, thus furnishing an- 

 other cause for their peculiar action under certain circumstances. 



The grain of the wood is a prominent factor also affecting the problem. 

 It U this factor, coupled with uneven shrinking, which is probably respon- 

 sible, to a large extent, for the action of the gums In drying. The grain 

 may be said to he .-nore or less Indeterminate. It is usually spiral, and 

 the spiral may reverse from year to year of the tree's growth. When a 

 lioard. in which this condition exists, begins to shrink, the result is a crop 

 of opposiu); stresses whose effect Is sometimes disastrous. The shrinkage 

 around the knots seems to be particularly uneven so that checking at the 

 knots is quite common. The cells of some woods, as western red cedar and 

 redwood, become plastic and soft when hot and moist, and they may col- 

 lapse. The gums are known to be quite soft and plastic, if they are moist, 

 at high temperature, but they do not collapse so far as we have been able 

 to determine. 



The properties of wood which nffect the seasoning of the gums, are In 

 order of their Importance: (1) the indeterminate and erratic grain; (2) 

 the uneven shrinkage with the resultant opposing stresses; (.'i) the plastic- 

 ity under high temperature while moist: and (41 the slight apparent lack 

 of cohesion between the fibres. The flrst, second and the fourth properties 

 are clearly detrimental, while the third may possibly be an advantage In 

 reducing checking and case-hardening. 



ExpEBiMr.NT.\L Work 



The speaker described seasoning work done on gum at the .Madison lab- 

 oratory. The material was furnished bv the Carrier Lumber & Manufactur- 

 ing Company. Sardis. Miss. The car of lumber contained aliout half 1st and 

 2nd. inch sap gum and half firsts and seconds inch plain red gum, 

 lengths 12 to 15 ft. and av«raged 12 In. wide. This stock was in the pile 

 six hours after leaving the saw. The 1st and 2nd sap gum In 12 and 14 

 ft. lengths was piled the latter part of December, 1914, and was in the pile 



five months. The Hi ft. stock and the iBt and Snd plain red gum wa« 

 piled In November, 1014, and was six months old. The (iHes were eighty 

 courses high and six feet wide. Tlie piles were spaced about .t or 4 ft. 

 apart. 



When unloaded at the Korest Products Laboratory, this material was 

 badly warped and checked and ronlaiiieil opproximateiy lo per cent moU- 

 ture expressed in per cent of the dr.v wood wefght. The boards were open 

 plied In a very careful manner In the ialioratory yard and covered over 

 with a tarpaulin to shed the rain. Kroin time to time, four kiln runs were 

 made in attempt to kiln-<lry the material successfully. 



The aim of the Investigation was to work out the proper methods of kiln 

 drying Inch air seasoned sap and plain red gum lumi)er. The problem 

 seemed to be one of reducing the already severe warping, to prevent the 

 formation of new checks, and avoid casehardenlng. 

 Ice Box Metiiud 



I'erhaps the most important factor in Ijood kiln-drying, especially In 

 the case of the gums, is tlie method of piling. Proper piling will greatly 

 reduce the loss due to warping. .V good metliod of piling is to place the 

 lumber lengthwise of the kiln and on an incline crosswise. The warm air 

 should rise at the higher side of the pile and descend between the courses of 

 lumber. The reason for tills Is very simple and the principle has been 

 applied in the manufacture of tlie liest ice boxes for some lime. The most 

 efllcli'iit r..'frigerfttors are Iced at the side, the Ice compartment opening to 

 the cooling chamber at the fop and bottom. As the warm air from above 

 Is cooled by melting the lee, it becomes denser and settles down Into the 

 main chamber. The articles in the cooling room warm the air as they cool, 

 so it rises to the top and again comes In contact with the Ice, thus com- 

 pleting the cycle. The rate of this natural circulation Is automatically 

 regulated by the temperature of the articles In the cooling chamber and 

 by the amount of Ice In the icing compartment, hcnc-e the efllclency of such 

 a box Is high. 



Now let us apply this principle to the drying of lumber. Urst we must 

 understand that so long as the lumber Is moist and drying, It will always 

 be cooler than the surrounding air. .Vs the lumber dries. Its temperature 

 gradually rises until when periect dryness results It Is equal to that of the 

 air. With this fact In mind. It Is clear that the function of lumber In a 

 kiln Is exactly analogous to that of the Ice in an ice box. I.e.. it Is the 

 cooling agent. Similarly the heating pipes In a kiln bring aliout the same 

 effect as the articles of food In the ice box, viz. they serve to heat the alr.l 

 Theri'fore, the air will be cooled by lumber, causing It to pass downward to 

 thi' piles. If the heating units are placed at the sides of the kiln, the 

 action of the air in a good Ice box Is duplicated in the kiln. The significant 

 point In this connection Is that the greener and colder the lumber, the 

 faster is the circulation. This is a highly desirable feature. A second vital 

 point Is that as the wood liecomes gradually dryer, the circulation automat- 

 ically decreases, thus resulting In Increased efllclency, because there Is no 

 need for circulation greater than enough to maintain the humidity of the 

 air as it leaves the lumber, and about the same as that of the entering air. 

 Therefiire, we advocate either the longitudinal Inclined pile, or edged stack- 

 ing, the latter being more preferable when possible. One by one Inch 

 crossers were placed every two feet. We have found that much less warp- 

 ing results with edge stacking as both sides of the boards dry at the same 

 rate and so shrink more nearly alike. This Is Important In drying gum 

 lumber. 



PREt.iMiNAnv Steamixo 



Because the fibres of the gums become plastic while moist and not without 

 causing defects. It Is desirable to heat the air dried lumber to about 200 

 degrees F. In saturated steam at atmospheric pressure In order to reduce 

 the warping. This treatment also furnishes a means of beating the lumber 



