Native Sources

of fresh to the acre can be expected. Sandy, well-drained soils and dry climates in Texas, New Mexico, and Arizona are well adapted for growing Materials canaigre. To assure good yields, irri- gation is desirable. By selection of planting stock, strains of high yield and Jerome S. Rogers content can be developed. Ex- loeriraental plots have been successfully harvested, with standard potato-dig- ging ecjuipment. Washing, shredding, Most of the vegetable used and rapid air-drying 1 or 2 weeks after to tan our many kinds of we harvest insure roots that can be stored get from other countries. If we w^ant to and shipped without spoilage. Har- be independent of foreign supplies and vested roots exposed too long in the air have domestic tannins adequate to become hard and difficult to shred. meet the critical needs of a national Damaged roots mold readily. emergency, we will have to increase Freshly dug canaigre roots contain our production of new tannins, develop 65 to 73 percent moisture. The tannin tannins from that can be grown content of the moisture-free roots usu- as farm crops, and salvage more tannin ally ranges from 20 to 40 percent. from waste barks. Some samples of wild roots have been Tannins occur naturally in most found to contain more than 43 percent materials, but relatively fcv/ tannin. The roots also contain 8 to 20 plants that arc rich in tannin are also percent sugar and 25 to 40 percent adapted for cultivation just for tannin starch. crops. Two native materials, canaigre Two native strains have been ob- and , seem to be well suited for served. They differed in color, in tannin crop cultivation and arc now being content, and in behavior in experi- studied by the Department of Agri- mental studies of leaching. culture. I'he probkuns encountered in ex- Canaigre, Ruinex hymeno se palus tracting tannin and making extracts Torr, belongs to the dock family. It is of high commercial quality from native to southwestern United States canaigre roots difí'er greatly from those and northern Mexico. Its tuberous met in preparing tanning extracts from roots, which look somewhat like sweet- or . The starch in canaigre potatoes, are rich in tannin and have makes it impracticable and inefficient been used in tanning leather for cen- to extract coarse shreds countercur- turies by the Mexicans and Indians. It rently with hot water, in accord with is propagated by roots, crow-ns, or the usual commercial practice as ap- seed. Canaigre planted in the fall grows plied to barks. The swelling and during the winter and blooms in early gelatinization of the starch by hot spring. The top dies back in May or water prevent efTective extraction of June, The roots remain dormant until the tannin. To overcome that diffi- fall, when they s]3rout again. Harvest- culty, several laboratory-scale ]:)roce- ing is usually done in July, August, or durcs were investipfated. One gave September. Under favorable^ condi- promising results. The properly pre- tions annual fields of aÍDout 10 tons of pared canaigre was extracted in ac- 709 710 1950-1051 YEARBOOK OF AGRICULTURE cordancc with the countcrcurrcnt ordinary solid quebracho extract (with principle, by which water at 104° to a tannin content of 68.5 percent and a 113^ F. went on the spent material in purity of 87.5). the tail leach, moved forward through In laboratory-scale extractions that several lots, and came ofT as a concen- used acjueous-organic solvent mixtures, trated head liquor from the finely those containing acetone or isopropyl divided fresh material in the head alcohol gave best tannin recovery. leach. Between each forward step the Both were more efficient than water liquor and partly spent material were and had the further advantage that subjected to vigorous mixing at 104^ to when the solvents were used in proper 113° F., followed by mechanical sepa- concentrations starch did not interfere ration of liquid and solids. This proce- in the extraction. Because of the costs dure gave leaching efficiencies of 75 of the solvent, fire hazards, and recov- to 85 percent. For example, from 100 ery problems, however, further study parts of canaigre roots containing 35.5 and an analysis of costs are needed to parts of tannin, 29.4 parts of tannin establish the economic feasibility of were recovered in the extracted liquor. their use. The sugars present in canaigre roots In laboratory tests, canaigre extracts are soluble and are extracted with the have been successfully used both alone tannin by water. When the extracted and blended with other tannins tor the liquors containing tannin and sugars tanning of good-quality of the and other nontannin substances are solcrleather type. concentrated, the tanning extracts pro- Several processes for the preparation duced are low in purity because of the of tanning extracts from canaigre are sugars present. We raised the purity of being studied on a pilot-plant scale. the extracts by removing the sugars by For each process, that entails the cor- fermentation, using specially isolated relation of drying, grinding, leaching, bacteria. Several strains of Aerobacter and clarification operations so as to acrogenes, obtained from canaigre obtain an integrated process. Also to roots and the soil in which canaigre be determined are the and grows, made effective growth and de- economic factors that govern the stroyed the sugars in canaigre liquors choice of commercial ec]uipment. î^oth without material loss of tannin. The batch and continuous leaching are be- principal products of this fermentation ing studied. The most promising results are 2,3-butanediol, acetoin, and ethyl have been obtained by fine grinding of alcohol. the dried roots. Tannin yields are en- Comparison of analyses of pow- hanced by the addition of less than 20 dered canaigre extracts made from un- percent of an organic solvent to the fermented and fermented canaigre leaching water, but its economic de- liquors shows that by fermentation of sirability has not been fully evaluated. iicjuors the quality of tanning extract can be greatly improved. For example^ SUMAC, a shrub that grows wild in in one case the sugar content of an ex- this country, has long been known as tract was lowered from 22.9 to 0.7 per- a source of tanning and dyeing mate- cent and the nontannin from 44.0 to rial. Its tannin is not well adapted for 28.7 percent, while the tannin content general use in tanning hea\y leather. was raised from 49.7 to 62.1 percent Its present use—to make lightweight and the purity from 53 to 68.4. leathers—might well be expanded, By the fermentation procedure, we however, so as to help meet the demand got canaigre extracts that compare ac- for additional domestic tannins. ceptably with some of the best commer- Sumac tannin, obtained from the cial tanning extracts, such as powdered , is vised as ground or as a (with a tannin content of liquid extract. Tanners of lightweight 61.3 percent and a purity of 66.3) and leathers like it because it produces soft, NATIVE SOURCES OF TANNING MATERIALS 711 durable, light-colored leathers of de- stock is slow in getting large acreages sirable feel. under cultivation, but it has the ad- Frequently a product of low quality vantage that high-quality strains can is obtained because woody stalks low be maintained by its use. Rich soil pro- in tannin are collected with the leaves, duces luxuriant growth, but then the deep piling during drying causes spoil- leaves are low in tannin and the yield age, or ex]3osure of the leaves to de^v of tannin to the acre is not greatly or rain causes loss of tannin. The cor- increased. rection of such unsatisfactory practices A survey of sumac that grew wdld will aid in obtaining a commercially over 12,000 square miles in southern acceptable product, and tanners will Virginia indicated that about 43,000 have kiss justification for their pref- long tons of dry sumac leaf could be erence for the imported Sicilian sumac, collected there annually. . Ira D. Clarke, A. F. Sievers, Workers in the Department have anci Henry Hopp, and I have studied found that sumac leaves of acceptable eight species of sumac native to the tannin content and commercial qual- eastern and southern parts of the ity can be ]Droduced from domestic United States to determine tannin con- species if correct procedures arc used tent and abundance. The results of in har\'esting and drying. our investigations are given in the The possible economical develop- Department Technical Bulletin No. ment of sumac for tannin, therefore, 986, Tannin Content and Other desen-es consideration. The develop- Charae¿eristics of Native Sumac in Re- ment involves the cultivation of high- lation to Its Value as a Commercial quality sumac strains as farm crops Source of Tannin. (1949.) and the mechanical harvesting and We found that leaves, leaflets, and handling of the product by improved flowers of sumac were high in tannin methods. Investigations are now in and that all other parts of the plant progress. were low in tannin and would lower The three domestic that the quality of the leaf product if mixed seem most promising for cultivation with it. In a statistical study of the as tannin crops are the dwarf sumac effects of genetic and environmental [Rhus copallina)^ white sumac {Rhus factors on composition, we learned glabra), and staghorn sumac (Rhus that leaves of male plants of Rhus typhina). All have compound leaves, copallina contained an average of 3.3 which average 32.5, 27.3, and 25.6 per- percent more tannin than those of fe- cent, respectively, of tannin on a male plants; that leaves of Rhus copal- moisture-free basis. They will grow lina and Rhus glabra that grew in par- on dry and sometimes rocky soil. tial shade averaged 2.8 percent less Dwarf sumac has winged growths tannin than leaves of similar plants along the midribs between the leaflets growing in full sunlight; and that date and black specks on new-growth of collection influenced tannin con- stalks. White sumac has smooth stalks tent, there being an average decrease and a bluish-white bloom, like the in tannin of 0.047 percent a day during bloom on plums, which covers the the summer. stalks and the underside of the leaflets. Yields of leaves calculated from Staghorn sumac has a hairy growth small plots of plants 1, 2, and 3 years along the stalks and leaf midribs. old indicate that 5/2 to 3 tons of dry Sumac can be grown satisfactorily leaves can be had from an acre under from seed or root stock, but roots must varying conditions. More data are be handled promptly or they will die. needed on methods of harvesting ap- No seed is yet available that can be plied successively for several seasons guaranteed to produce high-tannin to plots of an acre or more. plants. Propagation by means of root Sumac leaves dried rapidly at ordi- 712 1950-1951 YEARBOOK OF AGRICULTURE nary temperatures with good ventila- adult clone. It is incTcased by de- tion do not change in composition. blossoming the plant and is lowered by They produce good, light-colored growth in shade. Three-year-old seed- leather. Slow drying at ordinary tem- ling plants of the four species gave peratures, caused by poor aeration or yields at the following rates per acre: high humidity, means a loss of non- R. aromática, 416 pounds; R. glabra, tannin material, principally sugar, but 592 pounds: R. copalliita, 975 pounds; does not change the amount of tannin. and R. typhina, 2,250 j)ounds. Such partly decomposed leaves pro- E. L. Barger and J. M. Aikman, of duce dark leather. Drying at 212^ F. Iowa State College, developed a iTsults in a slight loss of tannin and power-driven harvester that was suit- sugar, but the product produces good, able for harvesting sumac from both light-colored leather. wild and cultivated stands. Under fav- In a commercial tanning test on orable conditions about 3 tons of green more than 330 dozen skivers, leaf could be harvested a day, an all three domestic species produced sat- amoimt equal to what 10 men could isfactory leather that was approxi- harvest by hand in a day. Tests were mately equal to that produced by also conducted on drying and mechan- Sicilian sumac. ical separation of leaves from woody F. P. Luvisi and Tra D. Clarke,at the stalks. Eastern Regional Research Labora- In the development of suinac as a tory, learned that a temperature of domestic tannin crop, machine meth- 212"^ F. was most efficient for extraction ods for harvesting, drying, and separa- for the determination of tannin. They tion of leaves from stems reduce labor also found that heat up to 212° F. had costs and aid in meeting competition only a slight effect on dry leaves, but from sumac from foreign countries that leaves were altered by steeping in where labor costs are low. water, apparently by a change of tannin into nontannin. Both tempera- Tn.R RECOVERY OF TANNIN frOm ture and time of steeping were factors. available supplies of imused and waste Ivan L. Boyd, in comprehensive re- barks could aid materially in meeting search on sumac at Iowa State College the present shortage in domestic tan- in cooperation with the Soil Conserva- nins. Among the barks that might be tion Service, found that four native used are Florida scrub [Quercus species—Rhus glabra^, R. copallina^ R. laevis), with 10 percent tannin; east- iyphina, and R. aromática—had possi- ern hemlock ( canadensis), 12 bilities for cultivation as sources of percent; western hemlock {Tsuga tannin and, because of their spreading, heterophylla), 15 percent: Douglas-fir, shallow root systems, were valuable in {Pseudotsuga taxifolia) ^ 10 percent; preventing soil erosion. Of these, R. Florida [Rhizophora man- glabra was the most promising for gle). 31.5 percent; and a mixture of southeastern Iowa. Propagation of the from the Tennessee Valley, which species by root cuttings gave a survival would probably average about 8 per- rate of 10 to 82 percent. Seed from the cent tannin. Although of acceptable four species treated with concentrated tannin content, some of the barks offer sulfuric gave an average germina- no promise as economical sources of tion of 13 percent. Better germination tannin. was obtained wnth seed selected from Bark of western hemlock, one of the clones yielding a high percentage of largest undeveloped sources, represents viable seed. Seedlings from R. glabra a potential annual sup])ly of about and R. typhina reach harvesting size 35,000 tons of lOO-percent tannin. It is in about 3 years. The tannin content not too promising, however, because of leaves increases each year in seed- the practice of floating logs down- lings but seldom exceeds that of the stream causes a loss of about one-half NATIVE SOURCES OF TANNING MATERIALS 7Ï3 OÍ the bark tannin and contamina- The vegetable tannins most com- tion of the bark on logs floated in salt monly used in making leather are wa- water. ter-soluble materials obtained from Florida mangrove bark is inaccessi- barks, , leaves, and —for ble and costly to collect. It probably example, the barks of oak, hemlock, would not yield more than 1^000 tons vvattic, and mangrove, the woods of of 100-percent tannin annually for 5 cfuebracho and chestnut, the leaves of years. sumac and gambier, and the fruits of The barks of the Florida scrub oaks valonia oak, myrobalan, tara, and di\'i might be recovered by hogging the logs divi. Of these, the one most extensively and branches and mechanically sepa- used in our leather is the tan- rating the bark from the wood by air nin from quebracho wood, which we flotation, as described by H. N. Calder- import from Argentina and Paraguay w^ood and W. D. May, at the Florida as solid extract. Second is the tannin Engineering and industrial Ex])cri- from chestnut wood, which is produced mcnt Station. The bark would be used domestically but may be exhausted as a source of tannin and the wood for soon because blight has killed nearly all paper pulp. The bark might furnish commercially important stands of as much as 5,000 tons of 100-perccnt chestnut. tannin annually for 20 years. Fifty years ago most of the leather L. F. Bailey and W. H. Gummings, produced in the United States was of the Tennessee Valley Authority at tanned with tannins from oak and Norris, Tenn., found that mixed oak hemlock bark. Today only a limited slabs could be extracted to yield about amount is produced from them. Small 3,000 tons of 100-pcrcent tannin a amounts of tanning extracts are made year. from domestic supjDlies of sumac leaves The Lak(î States region has su]3plies and pecan shells. All other vegetable of hemlock bark which, if salvaged, tannins are imported. should yield around 17,000 tons of Accurate data on our use of tannin 100-pcrcent tannin annually. The high are not available, but some idea of the cost of jX'cling and collection raises a amounts can be obtained from iinport question, however, as to the economi- figures and estimates of domestic pro- cal ieasibility of utilizing this bark to duction. From 1940 to 1949, 'the make tanning extract. United States consumed annually an Douglas-fir bark, now being inves- average of about 125,000 tons of 100- tigated at th(^ Oregon Forest Products percent tannin; more than 70 percent Laboratory, appears to have promise. of it was imported. Quebracho tannin, The investigators found tannin con- from South America, constituted tents of 7.6 to 18.3 ])ercent, and esti- nearly 70 jDcrcent of the foreign tannin mated that the average tannin content group and more than 50 percent of would be about 1.0 percent. They found the total consumption. Chc^stnut wood that the bark also contained an aver- tannin accounted for about 95 percent age of 7 percent of waxes and 5 percent of the domestically produced tannin of dihydroquercetin. They estimate a and about 25 percent of the total con- potential annual tannin recovery equal sumption. Tannin from w^attle bark, to more than 150,000 tons of 100- imported principally from Africa, held pcrcent tannin. If such a quantity of third place. Mangrove bark taimin, fir bark tannin could be ].")roduced eco- from Africa and South America, was nomically, it would aid greatly in solv- fourth. ing this country's tanning material Drillers of oil wells have discovered shortage. How^evcr, the tanning prop- that quebracho tanning extract, treated erties of iir bark tannin require further with caustic alkali, helps in regulating study to determine its suitability for the \iscosity and consistency of drill- making various types of leather. ing muds. ScvtTal thousand tons of 714 1950-19 5 1 YEARBOOK OF ACîRICIJLTURE extract are used annually for the pur- arc preferred: for others, vegetable- pose. To relieve that added demand, tanned leathers are better. Some syn- substitute extracts or other materials thetic tannins are often used in light- suitable for the purpose are being leather tannages. They ha\'e also been sought. used in some heavy-leather tanning, The essentiality of vegetable tannins but their prices are materially higher in the manufacture of leather is illus- than those of vegetable tannins. trated in figures for leather production Present domestic sources of tannin in the United States in 1949 (in are chestnut wood, oak and hemlock millions) : barks, sumac leaves, and pecan shells. Vßge- Mill- Most of the domestic tannin, prob- table- eral- Total ably more than 95 percent, is obtained Hides or skins: tanned tanned tanned from the wood of the American chest- Cattk_ !___ 8.2 15.2 23.4 nut, Castanea dentata. It is quite gen- and lamb_ 8. 5 20. 3 28. 8 erally known, as I said before, that the Calf and kip___ 1.0 9. 1 10. 1 and kid 34. 7 34. 7 that constituted the commercial stands of chestnut in the United States The minc^ral-tanned leathers were are being killed by blight, caused by a tanned principally with chrome but in- parasitic fungus, which was brought cluded and all other mineral into the country on Japanese chestnut tannages and also mineral-tanned trees planted on Long Island about leathers that were retanned with vege- 1893. By 1904 nati\'e were table tannins. dying. Progress has been made in de- Vegetable tanning materials were veloping blight-resistant chestnut trees used for tanning approximately 35 per- by G. F. Gravatt. Jesse O. Diller, and cent of the - leather, 30 per- Russell B. Clapper, of the Bureau of cent of the sheepskin and lambskin Plant Industry, Soils, and Agricultural leather, and 10 percent of the Engineering. and kip leather. Ira D. Clarke, E. T. Steiner, and R. Cattle hides, when vegetable-tanned VV. Frey, of the Bureau of Agricultural in their original thickness, yield heavy, and Industrial Chemistrv', studied the thick, firm leathers, w^hich arc espe- timnin contents of the blight-ix\sistant cially adapted for use as shoe soles, har- Chinese vhc^tnul. Castanea niollissirna, ness, luggage, and belting. Leath- and found that trunk wood from trees ers of those types take more tannin 16 and 25 years old contained 8.0 and than do the lightweight, soft, flexible 12.0 percent tannin, respectively, com- leathers used for shoe uppers, gloves, pai'cd with 8.4 percent for 14-year- garments, and fancy leather goods. old American chestnut. Although the One tanner uses a blend of vegeta- tannin content of blight-resistant ble tannins containing 51.2 pounds of chestnuts compares favorably w'ith 100-percent tannin to produce 100 that of the native chestnut, because of pounds of air-dry sole leather from the long time required to produce com- steer hides. A tanner of light leather, mercial stands, there appears to be no on the other hand, to produce 100 prospect for the development of a do- pounds of calfskin and sheepskin leath- mestic tannin supply from this source. ers uses, respectively, only 36 and 40 pounds of 100-percent quebracho tan- IN ANY STUDY of the possibilities for nin. Heavy leathers are tanned prin- the economical development and utili- cipally with vegetable tannins. For zation of available bark supplies, sev- light leathers, mineral tannages, such eral factors need to be considered—the as chrome or alum, are commonly quantities available, accessibility, tan- used. The properties of leather differ nin content, possible byproducts, and according to the tanning materials. the costs of bark, extract production, For some uses, mineral-tanned leathers and transportation. Of the barks in- NATIVE SOURCES OF TANNING IM A T E R I A L S 715 vestigatcd, the oaks from Florida and tanning materials that it needs for the the Tennessee Valley, the hemlock manufacture of leather d(î]Dends on the from the Lake States area, and the fir successful completion of investigations from Oregon and Washington ap- now imder way. We can probably best pear to have promise. The bark from attain this objective by a combination ' western hemlock would also be a prom- of two lines of activities—one, the de- ising source of tannin if it could be velopment of economical procedures salvaged from logs that have not been for the salvage and utilization of avail- floated. able supplies of oak, hemlock, and fir The production of tannin from farm barks; the other, the large-scale culti- crops has many desirable features. It vation and production of canaigrc, ofïers a new^ crop at a time of farm sur- sumac, and other tannin-bearing pluses. The production of canaigrc and plants ns farm crops. sumac will furnish two ty]:)es of tannin that will be available for blendins: with J.I:ROME S. ROGERS is a native of other tannins. Sumac will be adapted New York State. His undergraduate for light-leather tannage and for many training ivas at Syracuse University purposes could rc}Dlace quebracho. Ca- and his graduate work ai the Univer- naigrc will be a root crop that can be sity of Illinois. From 1909 to 1917 he harvested with availabl(^ farm machin- w-as with the Leather and Paper ery. Associated with the canaigrc tan- Laboratory of the Bureau of Chem- nin will be starch and sugar, byprod- istry. From 1918 io 1936 he was chemist ducts which may be used for pro- in, charge of the laboratories of Kistler, duction of fermentation products. Le s h & Co. and International Shoe Canaigrc crops can be largely ex- Co. In 1937 he returned to research panded or curtailed to meet rapidly on leather and. tanning materials in changing demands. the Department of Agriculture. Fie is The ability of this country to pro- on the staff of the Eastern Regional vide a major part of the vegetable Research Laboratory.

MOLDING OF BERRIES arising from mold growth on boxes used to transport berries from field to processing plant has been serious in the Pacific Northwest. In res]5onse to a request from the industry for help in solving the problem, the Western Regional Research Laboratory in 1948 set u}3 an emergency research project which produced a practical answer in time for the 1949 berry season. The method found most effective is to treat the wooden boxes with wax, so as to prevent the absorption of berry juices, which support mold growth, and to make washing of the boxes easier. The treatment consists of dipping the boxes in a molten mixture of 95 percent standard paraffin wax and 5 percent mici'o- crystalline wax under carefully controlled conditicnis of temperature and time. A simple control test, made by placing a drop of a blue dye solution on the treated box, tells whether the treatment has been done right. The treated boxes remain substantially free from mold grow^th throughout the season if properly washed after each use. Loss of due to mold damage is greatly diminished or entirely eliminated. Wax-treated boxes will probably cost less than untreated boxes in the long run, because untreated boxes must be replaced each year, w4iile the treated boxes should last two or three seasons.—W. D. Ramage^ West- ern Regional Research Laboratory.