/ -I CHANGE IN MOISTURE CONTENT CE LUMBER DURING RAIL SHIPMENT December 1927 SCHOOL OF FORESTRY LIBRARY UNIVERSITY OF FLORIOA No. R826 UNITED STATES DEPARTMENT OF AGRICULTURE FOREST SERVICE FOREST PRODUCTS LABORATORY Madison. Wisconsin In Cooperation with the University of Wisconsin CHAI7GS IIT MOISTURE CONTENT 07 LUMBER DURING- RAIL SHIPMENT^ By G. E. FRENCH, Assistant Wood Technologist Engineers are interested in the degree of seasoning at which standard sizes of lumber apply, and frequently also in the possibility of obtaining lumber of some specific moisture content that fits it for a special use without the risk of changes in dimension due to shrinkage and swelling- It is, therefore, im- portant to know to what extent the moisture content of lumber changes during the ltng rail hauls that are now a common necessity of lumber marketing. This paper presents the results of an investigation made to determine whether or not lumber placed aboard cars at the sawmill at a low moisture content will change in moisture content during transit to such a degree as to defeat the purpose of careful seasoning for general or specific uses. As a preliminary step in the study, representatives of the Forest Products Laboratory and of the Forest Service district products office, Missoula, Moat.,, early in 1926 determined the change in moisture content of six carloads of lumber shipped from Idaho to the vicinity of Chicago. The late winter and spring season was selected as the time for the tests because this is the period of highest humidity of the year. In the six cars tested containing largely inch-thick flat stock of white fir, ponderosa pine, and western white pine, the moisture change of material while in transit was slight except for some material with 30 percent average moisture content that lost about 5 percent. In view of the small changes which these shipments showed, the Forest Products Laboratory decided in 1927 to determine not only the change in average mois- ture content for carloads of lumber, but to show in what portion of the laad local changes, if any, were taking place. The cooperating company, whose plant is located in western Oregon, was shipping clear grades of Douglas.-fir kiln dried, to an average of 8 percent moisture content and common -grades of Douglas-fir kiln dried to approximately 20 percent. Five cars of flat clears were tested, one car of clear quarter-round and erown molding, and one car of common shiplap. Eighteen sample boards were placed in the same relative po- . sition in each car. They were protected from any extra moist boards in the vicinity by being placed between check boards of approximately the same mois- ture content as the sample. Each sample board was sampled for moisture content and weighed to the nearest hundredth of a pound at the time it was placed in the car. At destination (Chicago) the sample boards were again weighed and \ moisture content tests were made. As a check upon these two methods of deter- mining the change in moisture content the total weight of each shipment was -Published in Furniture Manufacturer, Dec. 1927. RS26 determined at the point of origin and destination "by weighing the car loaded and empty. The results obtained "by all three methods, namely, (l) change in weight of sample boards, (?) change in weight of total shipment, and (3) change determined "by moisture content determinations of the samples at origin a destination, were so similar that only those changes shown "by the sample "board weights need "be considered here. The data obtained are shown in the accompanying table and illustrated graph- ically in the diagrammatic cross-section of the freight car. Tor the five cars of flat clear Douglas-fir the average change in moisture content was a 0.2 percent increase (based on the oven-dry weight of the samples); for the more loosely loaded molding, 0.8 percent increase; and for the common lumber a loss of C.4 percent. The changes were so small as to fall well within the possible error of moisture determinations. The samples distributed throughout the loads gave no definite indications of local changes. As all of those shipments were made from the West Coast two-thirds of the way across the con- tinent, with only the ordinary precautions used in loading box cars during the wettest period of the year, it is quite reasonable to conclude that during the usual haul in good box cars no appreciable change in moisture content of lumber need be expected. This information is significant. It means that stock placed in the car in satisfactory condition as to moisture content will reach the unloading point in practically the same condition. If, on the other hand, it is received in bad condition by the consignee, the fault, unless the car is in a poor state of repair, must be with the seasoning methods' employed. The virtual elimination of this "unknown" between shipper and consignee brings the moisture content problem one step nearer solution. Change in moisture content of , Douglas-fir lumber shipped by rail during the winter season from the West Coast to the vicinity of Chicago. Carload shipment number Date shipped Date ; reached : consignee: j. Grade Average mo is-: Change in ture content : moisture con- when loaded stent in transit 1 2 3 U 5 Av. s ' 1. 25" Feb. k Pec. 10 Mar. 18 Mar. 25 1927 Feb. 10 Feb, 28 Mar. U Apr. 5 Apr . 16 May 25 May 2U Clears 11 11 11 11 Quarter-round and crown moulding Common Percent 8 8 10 9 7 ..8 8 21.0 + 0.2 + 0.3 + 0.3 - 0.1 + 0.3 + 0.2; + O.S - O.U R326 UNIVERSITY OF FlORIDA 3 1262 08929 1842 o.ctf +0.3* 1-o.iJ ] +0 .6*1 +0,2* +0.3* +0 iii) j,Q.lftj +0.8*1 Average change 0.2* 0.0* +0.U* j-0,2* -0.2* B] +0.3'* <* +0.2* +0,6* +0.5 * Diagrammatic cross section of freight car as loaded with clear grades of Douglas -fir. The small rectangles indicate the location of the sample "boards within load in the 1927 tests, Figures in small rectangles show average local change in moisture content of lumber during transit. R826