Paper Making - Future Fiber Possibilities
( Originally Published 1920 )
THE United States Department of Agriculture, In August, 1911, issued a treatise on "Crop Plants for Paper-Making," in which the author, Charles J. Brand, concluded: "There is some skepticism as to the failure of pulpwood supplies, but this is certainly poorly grounded.
During 1909 the quantity of spruce used was less by 40,000 cords than in 1907, but the cost was $2,000,000 greater. Present efforts in connection with reforestation of spruce and poplar are not extensive enough to produce any note-worthy effect upon the available supply within a generation.
"At the present rate of increase in consumption, it will require between 15,000,000 and 20,000,000 cords of wood for pulp and paper fiber in 1950. It will certainly be impossible to furnish this from the forests. If every acre cut over each year were reforested, it would be twenty-five or thirty years, or possibly even longer, before the trees could obtain sufficient size to warrant cutting. The forests can not recover from overdrafts continually being made on them. Hence it is only a question of a limited number of years until paper fiber must be grown as a crop, as are practically all other plants materials entering into the economy of man. While the conservation of only a few of the by-products of the farms yielding paper fiber can be accomplished profitably in the near future, and only a few of the plants promise to be money-makers immediately if grown solely for paper production, it seems very probable that raw products, now scarcely considered, may in a few years play an important part in the paper and pulp industry."
Two lines of research are now being followed by the United States Government. The Forest Products Laboratory of the Forest Service is investigating a large number of coniferous and broad-leaved trees, which have not hitherto been used in paper-making. These sources are likely to be the first which manufactures will turn to, as the processes involved are such as they are already familiar with, and the apparatus with which they are supplied is suitable.
The second line of research is being followed by the Bureau of Plant Industry, assisted by the Bureau of Chemistry, and is concerned with plants other than trees. Private investigations are also being carried on.
The following five requirements are given by the Bureau of Plant Industry, Circular No. 82, as to the availability of crop plants:
1. They must exist in large quantities.
2. They must be available throughout the year.
3. They must yield a relatively high percentage of cellulose.
4. The fiber cells or cellulose, must be of a highly resistant character, and must have length, strength and good felting qualities.
5. And must be of such a nature that the cost of obtaining the fiber will not be prohibitive.
Fibers complying with these conditions will come into commercial use whenever the increasing costs of wood-pulp reach a figure approximately equal to cost of producing cellulose from any other available source. Up to the present time this has not been brought about, but the steady in-crease in the cost of wood-pulp is approaching a level with which crop pulps may soon compete.
A synopsis of the fibers described in the circular referred to is given below.
CORN STALKS: On account of the enormous supply, corn stalks were first taken up by the Bureau. The yield of stalks per acre is conservatively estimated at one ton, and the annual product is placed as at least 100,000,000 tons, of which not over one-third is believed to be utilized by the farmers. Three products have been derived from the stalks:
1. Long fiber suitable for paper-making, composing 12 to 18 per cent of the bone-dry weight.
2. Pith pulp, suitable for paper specialties, equal to 15 to 30 per cent bone-dry weight.
3. Corn-stalk extract, obtained by lixivaition, and of value as a cattle food, a ton of stalks yielding 200 to 300 pounds of soluble solids.
It would require an immense area to supply a mill of moderate capacity, and the question of whether the derivatives of corn stalks could be sufficiently valuable to over-come the costs of harvesting and hauling, has never been answered by any experiment on a commercial scale.
BROOM CORN.—Broom corn contains a higher percent-age of fibers than corn stalks. In laboratory and semi-commercial tests, fiber yields of 32 to 40 per cent have been obtained with a comparatively low consumption of chemicals. The Bureau claims that results "indicate that this material is suitable for immediate use in paper-making on the basis of quality of fiber produced and yield of fiber secured." it is estimated that 450,000 tons is the approximate annual crop. Food extracts may also be obtained as well as the fiber.
RICE STRAW.—The Chinese and Japanese have for years used rice straw in paper-making, and it is regarded by the Government investigators as one of the most promising crop materials, the annual crop approximating 1,500,000 tons.
COTTON-HULL FIBER.-The lint adhering to the cotton hulls, after the long fiber has been removed, may be con-served as a by-product of the cotton-seed oil industry, and this fiber may be reckoned among the possibilities. Cotton stalks also have been the subject of experiment. The yield per acre, however, is not estimated at above 1,000 pounds, so that immense tracts would have to be covered in accumulating any considerable supply, and after the cotton crop has all been picked, negro help is very difficult to obtain.
BAGASSE.-Bagasse, or the refuse sugar-cane, is given rather scant consideration in the Government report. Its individual fibers are short, and the percentage of pith is large. Several small plants have had discouraging experiences in attempting to put this material to commercial use. Nevertheless, recent experiments carried on in the interests of the United Fruit Company, under the Simmons patents, point to a promising result. Under this process the cane is not treated in the usual manner of crushing for the extraction of sugar. Instead, it is shredded, dried, and the pith separated from the fiber. The product is then shipped in bales to re-fineries, where the sugar is extracted.
This method is said to achieve an almost complete extraction of the sugar, whereas the old method of crushing loses about twenty per cent of the sugar and injures the fibers. The Simmons process does no damage to the fibers, which though short, possess excellent felting properties. The pith, being cellulose of a non-fibrous structure, has a value for other industries than paper-making.
FLAX STRAW.—There is an abundant annual crop of flax straw. The avarage yield per acre is about one ton, and the total annual production about 3,000,000 tons. In the opinion of the Government investigators, it is a "most promising" material.
There are practical pulp men who deprecate the findings of the Bureau of Plant Industry. Martin L. Griffin, chemist to the Oxford Paper Company, of Rumford, Maine, in an article appearing in Volume XI, No. 2, of Paper for March, 1913, makes the following statement:
"There is a popular view, which has been erroneously fostered by the Government, that there are exhaustless resources of waste fiber in our country, suitable for paper, and a substitute for wood. I once thought so myself. It is very natural to think that the discarded stalks of sugar-cane, corn, cotton, rice, flax, and other plants, which mature annually, would prove an abundant substitute for wood.
"These have all been exploited for twenty-five years to my personal knowledge, with no visible results. A plant has one function to perform—it is to flower, fruit or make stalk. Its other functions are subordinate and produce only by-products. The stalk is the main product of the forest tree. No other fibrous material is so rich in cellulose; no other which lends itself so easily to paper-mill processing. It has no seasons of harvest; does not require curing; does not easily decay; requires no packing, and may be stored best in the rivers. All these waste stalks are pithy, bulky and perish-able, and would require much labor to gather, pack and ship. These are but a few reasons why we may expect no practical results from this source. Wood fills a place no other material can. There is no substitute for it."
In this argument Mr. Griffin ignores the fact that esparto grass is a crop which gives a yield of cellulose practically equal to wood, and of equal, if not superior, quality. Although it is not available for American mills, it is worth citing in contradiction to the fiat statement that "there is no substitute for wood." Furthermore, there is no evidence that the American crops furnish an inferior fiber, though the cellulose yield is less. It is quite possible that the low cellulose yield may be compensated for through the production of by-products along with the paper-making material. Hitherto, however, this low yield and other considerations, as expense of harvesting and packing, have been the factors which have retarded their development, but the increasing scarcity of wood, and its consequent advance is cost, is hastening the day when crop plants will become not only valuable, but necessary adjuncts to the paper industry.