Ways to Stop Losses of Tanbark

Ways To Stop Losses of our domestic tannin when chestnut extract is no longer available. As addi- tional supplies of bark tannin arc needed, it is important to handle peeled Tanbark bark so as to prevent loss from im- proper curing. The time when the bark of chestnut Marvin E, Fowler oak and hemlock separates easily from the wood differs from year to year, depending on the condition of the tree, rainfall, altitude, exposure, and tem- One way to husband our limited re- perature. sources of vegetable tannin materials is Chestnut oak bark peels when there to utilize them as fully as possible. is abundant soft sappy tissue beneath That, in turn, calls for cutting out the it and before the bark and wood tissues wastes now resulting from practices are bound together by interlocking that do not pre\^cnt deterioration. growth projections. Usually that is Chestnut wood is the most impor- from just before the time when the tant source of domestic tannin for mak- buds swell until the leaves reach ma- ing heavy leather. Nearly all this wood ture size. The period normally lasts 6 now being utilized is from trees that to 8 weeks, but is sometimes shortened have been killed by an introduced by a long spell of dry weather. fungus blight. Although dead trees can In hemlocks, the growth projections be used for extracting tannin, they will do not form and bind the bark to the eventually succumb to windthrow, de- wood, and usually the sa].)py tissue be- cay, or other deterioration if left in the neath the bark is sufhcicnt to permit forests. Extract plants can no longer ]3eeling from (ârly spring until autumn. supply the tanneries with all the chest- The bark tightens earlier on oaks nut extract they need. After the tannin and hemlocks of low vigor than on fast- has been extracted, many plants utilize growing trees. During the peeling sea- the spent wood for pulp in making son, the bark peels most easily right paper and other pulpwood products. after a tree has been cut. It tightens Bark from the chestnut oak and hem- rapidly as the tissues dry, Ptemlock cut locks comes next to chestnut wood in in the winter, however, usually peels importance as domestic sources of tan- satisfactorily the following May or nin. Their average tannin content is June. Bark peeling of both chestnut about 11 percent for hemlock and 12 oak and hemlock can begin early in percent for chestnut oak. The shortage spring at lower elevations and on in chestnut tannin increases the exist- southern slopes. The operations can ing need for oak and hemlock tannin. finish on higher and northern slopes Tanneries that use those barks have where the bark is slower to tighten. been unable to obtain as much bark as The heavy bark at the base is usually they need, even at higher prices. For peeled before the tree is felled. The some years we have had to import trunk is girdled about breast high and large quantities of tannin matí^rials— is peeled to the ground. Some peelers more than two-thirds of the amount remove the bark from the stumps after we need to make our leather. the trees have been cut. It is easier to Bark will probably provide most of ]3eel the bark from the underside of the 716 WAYS TO STOP LOSSES OF TAN BARK 717 trunks if they are felled across a log East and in the Lake States, improp- or on uneven ground. erly cured bark was found to contain After trees are felled into open less tannin than properly cured com- spaceSj encircling cuts arc made with parable bark. Under the most adverse an ax every 3 or 4 feet on chestnut conditions the badly molded bark oak and every 4 or 5 feet on hemlock. contained up to 25 percent less tannin. Then, with an ax or the sharp side of a Under normal weather conditions, spud, the bark is split lengthwise be- no significant diiTerence exists between tween the girdling cuts on the top of the l.)ark spread out to dry for several days felled log. before being placed in ricks and bark Chestnut oak bark that has begun ricked immediately after it is peeled. to stick can be loosened, and peeling But wet bark should be spread out until raade easier, by pounding it with the the free surface moisture has evapo- butt end of a poleax or with a sledge rated before it is placed in ricks. Bark hammer. The bark is peeled from the placed in ricks whiles the outer, or ross, tree with a blunt instrument, such as side is wet may mold and deteriorate. a spud. Bark 8 to 18 inches wide is easiest to handle. Smaller pieces in- OPEN, DRY, and well-ventilated crease labor costs, because the bark is places are best for bark ricks. A rick moved by hand in the woods and at the of bark in a damp, poorly ventilated tanneries or extract plants. Such bark place may mold ancl cause a loss of may also deteriorate more in storage. tannin. Ricks are usually 3 to 4 feet During a good bark-peeling season liigh and 6 to 8 feet long. They are and with mature trees, a man can fell built oir the ground. Bark may be and peel an average of a ton or more stacked across two logs, so that air of bark a day, but production varies can circulate under the rick. The with ^veather and woods conditions. outer, or I'oss, side of the bark should Hemlock bark generally ]3eels more be turned up. Occasional narrow easily than chestnut oak bark. It is pi(x:es inserted crosswise at the front taken ofí' the tree in larger pieces. A and back of the rick will separate the ton of bark is usually obtained from bark and improve ventilation. Rais- 1,500 to 2,000 board feet of hemlock, ing the front of the rick with a few depending on the size of the timbcT extra pieces of bark permits drainage of and the thickness of its bark. Some- rain water. Large pieces of bark placed times a ton of bark can be obtained sliinglewise on top will keep out wâter. from 1,000 board feet of large virgin Bark left scattered in the woods, even hemlock. if the irmer side is turned down, does Under normal conditions, if the not pure so satisfactorily as that placed bark is handled properly, it will cure in ricks. In some operations the crev/ satisfactorily without developing mold ]Deels bark during the morning and or decay. Long rainy seasons or fre- early afternoon and then stacks the quent periods of dense fogs may create bark ]3eeled that day. In other o])era- conditions favorable for the develop- tions the bark is not stacked until the ment of molds on even the best handled second day. In still others one man bark. The results of experiments con- stacks it continuously. Thin hemlock ducted cooperatively by tanneries, ex- bark should be stacked soon because it tract plants, and the Department of curls easily while drying. Agriculture indicate a relationship be- Bark should be left in ricks in the tween curing methods and quality of woods until it is dry enough to break bark. Under adverse curing conditions, with a clean fracturt^—usually 2 weeks bark may remain very wet and start or longer. Aftcn' drying, it may be left severe molding. In controlled experi- tlien^ for several months, if more con- mc^nts with chestnut oak bark in the \'enient to the operator and bark buyer. East and with hemlock bark in the Bark is usually allowed to age for at 718 19 5 0-1951 YEARBOOK OF AGRICULTURE least 3 or 4 months after peeling before Dirt and black mold on bark are being used for tannin. objectionable. Logs from which bark Properly cured bark is clean, has a is to be peeled should not be skidded bright flesh on the inner side, and is through mud or floated in streams or free from excess moisture. It breaks ponds. clean and not in strings, and it is not Leaving peeled logs on the groimd molded or mildewed. But improperly until the peeling season is over or curcid bark may be dark and covered until the following winter results in with molds. Such bark is likely to con- \-cry little deep checking and most of tain less tannin than if it had been the crac:ks are removed in the slabs properly cured. when the logs are sa\\'ed into construc- It is customary to arrange \vith a tion lumber. Peeled wood also may be tannery or with a bark buyer for the used for railroad ties, mine props, posts, sale of an estimated c[uantity of bark and paper pulp. before peeling is begun. The distance Your regional or extension forester the bark must be hauled to market or or county agricultural agent can give to a railroad siding for shipment by you information on markets for bark rail is an imjjortant consideration. and peeled trees, and on areas in which Bark is usually purchased by wêight. tanbark stumpage is available. A cord (4 X 4 X 8 feet) of cured bark weighs approximately a ton. Bark MARVIN E. FOWLER is a pathologist buyers generally dock the price for in the Bureau of Plant Industry, Soils, bark improperly cured, compensating and Agricultural Eniîneeriiig. He has at least for the weight of excess mois- investigated a number of diseases of ture.

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