Prelir Note on Current Use in the United States (l9l)

Transcription

1 i, uuur FOT6T PROOUCTS LABOR.4TORY. LIBRARY SUPPLEMENTARY flfori1ation ON BRAZILIkN kruckripl ("PARANA PINE")) Prelir Note on Current Ue in the United State (l9l) By ELOISEGERRY and MAXON Y. PILLOW Foret Product Laboratory, Foret Service U. S. Department of Agriculture, Madion, Wiconin Interet in "Parana pine" (which i not a pine, although it i a conifer or oftwood) i o widepread that the following information ha been collected tö ue in anwering the many inquirie about thi wood now being received at the Foret Product Laboratory, Some invetigation, bearing on the ue of Parana pine in the United State, have been made at the Laboratory to meet new need for information General information on the characteritic of the wood i given in the Foreign Wood Leaflet, Brazilian Araucaria (Parana Pine), by W. D. Bruh (19L) that i obtainable at the Foret Product Laboratory, Madion, Wi, The Intitute National do Pinho, Rua Mexico L, Rio de Janeiro, Brazil, ha iued (l9l8) a booklet on "Claification and Grading of Brazilian Pine." Thi can be obtained from the Brazilian Government Trade Bureau, l Fifth Ave., New York 17, N. Y, The latter intitution iue a pamphlet entitled, "Timber in Brazil," (l9l6), which i alo free upon requet and contain a ection on Parana pine and it export. Parana pine i undoubtedly a very ueful wood. It relatively uniform texture, availability in good ize of clear material, and current price caue thi wood to be much favored at preent, It hould be noted that preervative treatment i recommended for Parana pine to be ued in poition where decay may be a factor. Thi may be in the form of dip treatment with water-repellent preervative meeting the minimn tandard of the National Woodwork Manufacturer Aociation, Inc., 332 S. Michigan ve., Chicago L, Ill., which would 2 provide coniderable protection under ordinary ue requirement in building.- Some dipping tet at the Foret Product Laboratory howed relatively large aborption of the water-repellent olution, but practically no difference in amount aborbed by arwood and by heartwood. The relatively large aborption, however, till wa below amount that might be expected to interfere with painting. For ue under more evere condition, more thorough impregnation i deirable, uch a that recommended in Federal Specification TTV, 7l C (June 7, l9o). ½aintained at Madion, Wi., in cooperation with the Univerity of Wiconin. Freervative Treatment of Window Sah and Other Miliwork, by F. L. Browne. Foret Product Laboratory Rept. No. R9l9 (l9). 1May be obtained for from the Superintendent of Document, Government Printing Office, Wahington 2, D. C. (tamp not accepted). Rept.No.SR-19 (revied) -1- Agriculture-Madion

2 Kiln Drying Parana pine i being marketed in the United State for molding, ah, and general millwork. Thi lumber i being received in condition varying from green to partly air dry. Some buyer who have kiln dried Parana pine have reported difficulty, epecially with warping, at time, however, the Foret Product Laboratory ha been informed of Parana pine being atifactorily kiln dried commercially by the following chedule: Moiture content Temperature From To Dry bulb : Wet bulb Percent Percent ; F. F. Initial : : : ; : 150 : : : Final 170 : 116 z Recent kiln drying experiment at thi Laboratory, however, howed that Parana pine can be dried at appreciably higher temperature than thoe ued in the foregoing chedule. On the bai of thi vrork, the following chedule i recommended for kiln drying Parana pine lumber. Thi chedule i divided into two portion (i) temperature and (2) humidity. The temperature chedule for both 1- and 2-inch green or air-dried tock i a follow: Moiture content : Dry-bulb temperature From To Percent Percent F. Initial : 30 : ; : 15 : Final 200 z Rept.No.SR-l9 (revied) -2-

3 The humidity chedule for 1- and 2-inch green tock i a follow: Green tock Moiture content : Wet-bulb depreion From : To : 1-inch lumber : 2-inch lumber Percent : Percent : F. : O F. I I I Initial 7 LO : 35 : ll : 30 : 20 : : 25 : : 20 : 50 : L1O 20 : Final 50 : 50 The humidity chedule for 1- and 2-inch air-dried lumber i a follow: Air-dried lumber Moiture content : Wet-bult depreion From : To : 1-inch lumber : 2-inch lumber Percent : Percent : F. : F. Initial : 30 : 10 : 7 30 : 25 : 1L. : : 20 : : 15 : 35 : : 50 : L0 10 t Final : 50 : 50 When the tock i green the firt chane in the wet-bulb depreion i made at an average moiture content of LiD percent. If the tock i air dried, ue an initial wet-bulb depreion a indicated for the average moiture content o the tock. For example, if the average moiture content i 23 percent the initial wet-bulb depreion for 1-inch tock i 20 F., and for 2-inch tock it i 15 F. Thee chedule are recommended a a bai for developing a time chedule of the type commonly ued for the kiln drying of oftwood. Rept.No.SR-l9 (revied) -3-

4 ORSQ FOREST PRODÜCIS Equalization and conclitioning treatment are frequently given in the f inal tage of drying to reduce the variation in moiture content between board, to etablih a uniform moiture content within each board, and to relieve cae-hardening tree in both the trarvere and longitudinal direction. The condition to etablih within the kiln during thee treatment are dependent upon the final moiture content deired. A general guide for equalizing and conditioning Parana pine i a follow: (1) Dry the driet ample in the kiln charge to a moiture content 2 percent below the deired final average moiture content. (2) P oon a the driet ample reache the value pecified in (1), etablih an equilibrium moiture content condition in the kiln equal to that value. (See table 1.) (3) Allow the kiln charge to equalize until the wettet ample in the charge reache the deired final average moiture content. ()1) A oon a the wettet ample reache the value pecified in (3) place the kiln charge on a conditioning treatment at an equilibrium moiture content of 2 to 3 percent above the deired final average moiture content, () A.11ow kiln charge to condition until the tock i free of caehardening. After a number of charge have been atifactorily kiln dried, equalization and conditioning treatment can be put on a tandard time bai. The ue of relatively high temperature reulted in the advantage of appreciably hortening the time that wa required for kiln drying a charge of Parana pine. In addition, there wa no eential difference with repect to eaoning defect in end-matched board dried at the relatively low temperature and at the higher terapeature. The warping that occurred in the board in thee experimental kiln run wa due to the preence of compreion wood and the everity of warping wa not affected by the kiln-drying temperature. Effect and Detection of Compreion Wood In general, the Parana pine kiln-dried commercially ha been found, for the mot part, to be traight when it wa ripped and reawed. Some piece, however, were found to be omewhat warped even before ripping and more markedly afterward. In a number of cao thi wa caued by the preence of an abnormal type of wood known a compreion wood. Compreion wood may occur in any oftwood (conifer) due to condition affecting the growth of the tree in it lifetime. In piece of lumber that contain both normal wood and compreion wood, the exceive longitudinal Foret Product Laboratory Tech. Note 213. ReptNo.SR-1 (rev.) -Lt-

5 Table l.--relative humidity and equilibrium moiture content table for ue with dry bulb temperature and wet bulb depreionl ' ïiuiiuuuih:hiii:::i:iih::ii:::h: DiUUUUUD?1P1 1Relative humidity value above and wood equilibrium moiture content value below diagonal line.

6 hrinkage of i1i compreion wood caue internal tree along the grain. When euch piece, even if apparently r1atively traight, are planed, ripped or reawed, warping frequently occur. It i uually poible to recognize compreion wood and then exclude it from ue where it preence would caue eriou trouble. The appearance of the growth ring aid inpector in recognizing compreion wood in the lumber. Compreion wood may be le conpicuou in Parana pine than in mot of our native conifer but, neverthele, caue warping in ome Parana pine lumber. In Parana pine, certain characteritic of color, texture, and behavior of the board ignify the preence of compreion wood. Ditinctive color and texture of compreion wood are mot eaily recognized on planed urface and frehly awed end grain, ince weathering obcure the particular appearance by which compreion wood i recognized a an abnormaltype of wood, v:arping i a defect that i frequently caued by large difference between compreion wood and normal wood in hrinkage along the grain. Thi defect ignifie the preence of compreion wood in rough lumber. The extent of warping ten.d to be proportional to the amount of drying from the green condition of the lumber; that i, partly air-dry lumber with compreion wood i warped le than thoroughly kiln-dried lumber The characteritic that ignify the preence of compreion wood in Parana pine are: 1. On planed urface of apwood in board, compreion wood ha a yellow to brown color, in contrat to white or cream-colored normal wood. 2. In heartwood, difference in color between compreion wood and normal wood are mall, Compreion wood, however, uua'ly i deep brown in color, while normal heartwood i grayihbrown and frequently ha red treak, o that the compreion wood can be recognized by it difference in color from normal heartvrood. 3. Compreion wood tend to be preent in certain growth ring and abent in adjacent ring o that treak of thi abnormal type of wood and of normal wood frequently are preent in the ame board. )4. The texture of compreion wood appear to be harder or more horniike than that of normal wood, and the growth ring of compreion wood are wider. Thee characteritic are een readily on moothly cut end grain of Parana pine board. 5. Surfacewie bowing i the mot comnion type of warping. It can be een even when light by turning board on edge and ighting along the upper edge to determine whether they are traight or warped, 6. Edgewie crooking i not o common in partly air-dried lumber a it i in kiln-dried lumber. In the latter, crooking can be een by ighting along the edge of board a they lie flatwie on a pile of board or other urface. Even though the crook i le than an inch in a 16- to 18-foot board, it indicate the preence of compreion wood. Compreion Wood Caue of Bowing and ing Indutrie, Nov eiting, by M. Y. allow. Wood Work- Rept.No.SR-19 (rev.)

7 7. Relatively long plit, i foot or more in length in comparion with horter end check are indication that compreion wood i preent in Parana pine board. Inpection of kiln-dried Parana pine i recommended for detecting the preence of compreion wood in order to minimize warping when lumber i to be manufacturedfor miflwork and ued under condition that are ubject to large change of moiture; for example, window ah. The lumber hould be examined by inpector who have become familiar with characteritic of color, texture, and the action of compreion wood in cauing warping. Thee exaiiiination can be made during the handling and grading of lumber, along with exnination for other defect not permiible in certain kind of miliwork, There are limit within which it i practical to detect cornpreion wood in Parana pine lumber for general miliwork, Small amount of compreion wood, in fact, are not likely to caue eriou warping in finihed piece that are atifactorily traight, that i, traight enough o that they can be readily aembled a ah, frame, or trim. On the other hand, lumber that i warped badly when it i ripped i impoible to ue atifactorily. Experience ha hown that by egregation of bowed and crooked rough board after kiln drying the remainder of the lumber when ripped into narrow piece howed only light warping in a relatively few piece. The egregation excluded mot of the piece with large amount of compreion wood and the excluded material wa uable in the form of mall piece in which orne warping wa not a eriou defect. Rept.No.SR-l9 (rev.) -6-