Boom! - explosive growth in the cellulose industry

"Silk being nothing but dried-up liquid gum," wrote Réaumur, the French scientist, in his "Histoire des Insectes", published in 1764. "Why can't we make silk with gum and resin?"

No real progress was made toward the production of a practical artificial fiber until after the discovery of nitrocellulose, or guncotton,** by Schoenbein in 1845. This discovery really paved the way for the coming of rayon.

In 1855 George Audémars, a Swiss chemist, took out a patent for transforming a dissolved nitrocellulose into fine threads.

In 1888 J. W. Swan, an Englishman, obtained a fiber by dissolving nitrocellulose in acetic acid, and in the following year he exhibited fabrics made from this fiber.

The real credit for developing a practical textile fiber, however, is generally given to Count Hilaire de Chardonnet, who will go down in history as the father of the rayon industry.

Chardonnet was a pupil of the great French biochemist, Pasteur, whose researches into the diseases of the silkworm are among his most notable contributions to science. It is almost certain that Pasteur's study of the silkworm drew the attention of his pupil to the idea of making silk artificially.

In any case Chardonnet started experimenting with the idea in 1878. For a long time he studied closely the processes by which the silkworm transforms the material of the mulberry leaf, which is its only sustenance, into silk, in the hope that he could duplicate them. Failing in this he tried another tack.

He knew that the chief constituent of the mulberry leaf is cellulose, and he set about producing silk from cellulose. Finally, in 1884, he produced a fiber obtained by dissolving nitrocellulose in alcohol and ether.

It is worth noting that Chardonnet did not call this fiber artificial silk. In a memoir to the French Academy of Science he described it as "an artificial textile material resembling silk." He had set out to produce silk artificially. What he actually produced was not silk. It was a new fiber resembling silk in appearance, but distinct from it in chemical composition and in most of its physical characteristics.

In 1889 Chardonnet held an exhibition in Paris of fabrics made from his new fiber. This exhibition attracted wide attention. More important still it attracted capital. As a result the first factory for producing artificial silk was established at Besançon.

Chardonnet's fiber had a number of serious faults. Chief of them was the fact that, since it consisted of nitrocellulose,** it was highly explosive.

This fault was eventually overcome by a method of denitration. Various improvements have since been made in the process of making this fiber and in the technic of production.

Essentially the Chardonnet process is as follows: Cellulose, obtained usually from cotton linters, is immersed in a mixture of nitric and sulphuric acid, which transforms it into nitrocellulose. This is dissolved in alcohol and ether, and the resulting collodion or viscous solution is forced through glass tubes with tiny bores, emerging in the form of fine filaments which harden as they come into contact with the air, through the evaporation of the alcohol and ether, and which are subsequently denitrated in a bath of hydrosulphides.

In 1890, the year following the Paris exhibition of Chardonnet's product, Louis Henri Despaisses developed a process of making a textile fiber by dissolving cellulose in ammoniacal copper oxide. Mechanically the methods used in making fiber by the cuprammonium process are similar to those used in the Chardonnet or nitrocellulose process, but the chemical agents employed are different. The dissolved cellulose is spun into filaments which are passed through a mixture of sulphuric acid and water, and subsequently are washed in acetic acid.

The next important development in the evolution of synthetic fibers was the discovery of the viscose process by three English chemists, C. F. Cross, Edward J. Bevan and Clayton Beadle. The discovery was the outcome of a study of alkali-cellulose and mercerizing reactions conducted by these men.

In 1892 they developed a method of treating cellulose with caustic soda, producing an alkali-cellulose xanthate, or jelly-like substance, which they called viscoid. This opened up enormous possibilities, for it promised a cheaper product than could be obtained by either the nitrocellulose or cuprammonium processes. But great technical difficulties stood in the way of its effective use and the first attempts to produce viscose fiber on a commercial scale met with failure. The process, however, was gradually improved through research and experiment. The invention of a spinning device, known as the Topham box*, by Charles F. Topham in 1900, marked a big step forward in its development, and it has since gone forward by leaps and bounds until it is now accountable for about 90 per cent of the total world production of rayon.

The result was the development of the textile fiber now familiar to the trade as Celanese. The special grade of wood pulp prepared for the rayon industry contains about 90 per cent alpha cellulose, while cotton linters contain about 95 per cent.

Wood pulp is preferred because it costs less.

Viscose producers use wood pulp almost exclusively, but sometimes with an admixture of cotton linters for yarns of the finest quality.

The major chemicals used in the viscose process are very cheap compared to those used in the other processes. This advantage is offset to some extent by recovery methods which enable producers employing other processes to save a certain proportion of the chemicals used. Nevertheless, the use of cheaper chemicals, as well as of wood pulp instead of the more expensive cotton linters, gives the viscose process a distinct advantage from the point of view of cost. For this reason about 90 per cent of the rayon produced today is made by the viscose process.

The kind of wood pulp used by the rayon industry is known as bleached bisulphite pulp, and is prepared as follows: The wood chips are cooked in a solution of calcium bisulphite for nine to fifteen hours at a temperature of 140 to 150 deg. F. This dissolves the lignin, or woody matter, without affecting the cellulose. The resulting pulp is drained, washed free from chemicals and bleached with hypochlorite. After another washing it is floated on sieves over rolls, which reduce the moisture content. Then it passes through steam heated rolls, which dry it thoroughly, and from which it emerges in the form of a thin board. This board is then cut up into convenient sizes for shipment.

A downside to the Southern timber industry -

Chip Mills Supplying the industry are clear-cutting the south. In the thicket of the Carolina Lowlands, the whirring buzz and grind of a lone chip mill disturbs the summer symphony of rustling branches, crickets and the guttural call of wild turkeys. As the highly-automated leviathan roars with efficiency, stripping bark and grinding trees into usable flakes for the paper and pulp industries, hunters and environmentalists do a little roaring of their own. Concerned the voracious chippers will devastate Southern forests, their interest groups are calling for heightened regulations and a moratorium on new mills until their impacts have been studied.

A year ago, biologist E. O. Wilson and 100 other scientists cosigned a letter calling for a moratorium on chip mills until a federal study is completed. Their main concerns were disappearing hardwood forests, impacts on wildlife and waterways, and clearcutting.

Environmentalists have been quick to point fingers at chip mills for devastating forestry practices. But the industry insists it's "out of the loop" concerning timber cuts, since operators purchase their supply from private landholders. Industry officials are so infuriated, many refused to comment.

But processing the whole tree is exactly what has brought the mills under fire: because lumber is chipped into one-inch pieces, any size scrap of timber will do. With new markets opening up for treetops, undersized trees, and forked or crooked specimens, landowners have added incentive to clearcut a site for quick profits, instead of harvesting selected trees to be cut into boards. And timber previously left behind to continue maturing, or that provided wildlife habitat or eroded to replenish soils, now finds itself in the steely mouths of the chippers.

A 1998 U.S. Forest Service report says clearcutting accounts for 13 percent of logged land in the South. And because the chips are needed for everything from rayon and plastics to particleboard and paper, chip markets continue growing.

Timber giant Willamette Industries says chip mills allow landowners to merchandise otherwise unusable trees, discouraging forestry practices like "high-grading" (cutting only the healthiest trees). "Clearcutting is often the best tool to assure a rich, diverse forest," claims Willamette's web site. "Many songbirds and other types of wildlife require open areas for nesting and food gathering."

"Companies are working with private landowners to teach them sustainable harvesting," says Carson. "They provide free seedlings, the state provides management assistance, and people generally take it," he adds. The trouble is, the foresters doling out advice are usually trained in industry-friendly timber management.

As jobs grow scarce in many rural regions, chip mills have become the matches to dry kindling in local council debates. Because chip mills employ very few people - averaging six to 15 employees - and an increasing number of wood chips are being exported, local economies are losing out on much-needed processing jobs.

Pallet makers, saw millers and other solid wood manufacturers have criticized chip mills, accusing them of driving up hardwood chip prices as Japan becomes more and more willing to pay top dollar for exported chips. Furniture makers and sawmill operators fret over supply, too, as forests continue dwindling from chip mill impacts.

"Removal of softwoods in the South has already exceeded growth by 12 to 14 percent," estimates Smith. This forces the industry to resort to hardwoods to make up for the lack of resources; in fact, hardwood chip exports increased by 500 percent from 1989 to 1995 in the Southeast. "Chip mills can devour in one month the amount of wood an average sawmill consumes in a year," explains Smith. 

Carson argues that in many southern states, growth is exceeding cutting. "But the industry is promoting more monoculture plantings to meet increasing projected demand," adds Smith.

"'Plant 'em thick and cut 'em quick' is their motto. And there are no government programs in place to encourage diversity. The incentives are for genetically engineered loblolly pines."

And while the industry has no incentive to curb demand, it's gradually looking at alternatives to the fiber supply.

"To use agriculture waste, hemp or kenaf in the mix would require an enormous amount of money to upgrade. These companies are heavily invested in timberland, too. The industry needs investments in different infrastructure."

From: E/The Environmental Magazine By Tracey C. Rembert

* Topham's Box Ingenious Fred Topham, a glass-blower, help devise ways to spin the new material. His 'Topham's Box' enabled it to be spun into a silk-like thread. The Kew Viscose Spinning Syndicate produced artificial silk (later named 'rayon') until 1904, when they sold out to Samuel Courtauld & Co. In 1905 manufacture was moved to Coventry.

** More about guncotton:

Guncotton was first manufactured by Schonbein in 1845, but proved dangerous to handle until it was rendered safe by the method of purifying, pulping, and compressing it. It is produced by the action of sulphuric and nitric acids on cellulose in the proportion of three parts of sulphuric to one part of nitric acid.

Under the action of the acids, according to their strength and methods employed, trinitro, binitro, and mononitro cellulose are produced, guncotton being the first-named, that is, trinitro cellulose.

It is only soluble in acetone; unconfined and ignited it burns away rapidly, or struck by a hammer on an anvil part of it explodes, the remainder being blown away; when heated to a certain temperature it explodes, and when confined or compressed, it explodes from shock, heat, or detonation. It detonates by influence.

To Mr. E. O. Brown is due the credit of discovering that wet uninflammable gun-cotton is capable of being detonated by a strong fulminate detonator, or an ordinary detonator with a priming charge of dry gun-cotton, the size of which depends upon the percentage of water contained.

This discovery greatly increases the value of guncotton as a military explosive, not only for submarine work, but also as an explosive for shells; for wet guncotton is not affected by shock, failing to explode when penetrated by rifle bullets, or when loaded in shells, upon shock of discharge; is comparatively insensible to sympathetic explosion, and is not exploded by heat.

In 1871 the English Government tested this last named quality by burning in bonfires two lots, of a ton each, of guncotton containing 30 per cent moisture. In one case the explosive was in discs in a closed tank, and in the other it was divided among eighty closed packages.

In both cases the guncotton burned away without exploding.

Steps have been taken to coat discs of wet compressed guncotton, so as to enable it to retain its constituency by preventing the moisture from evaporating, and decomposition taking place.

In 1883 Von Forster and Wolff patented dipping guncotton in acetic acids for a few seconds which dissolves the cotton on the surface and forms a coating. But this was found to crack, so they now coat the disc with paraffine, and only treat the hole in this manner to facilitate detonation. Schulhof has patented a so called weatherproof guncotton which is said to possess non-hygroscopic qualities, to be insensible to shock or blow, and to be capable of exploding by detonation or heat of over 300 [degrees] F.

He impregnates dry guncotton with molten tallow or mutton fat, getting rid of the superfluous grease by pressure and washing with bisulphuret of carbon and benzine.

Source: Ingersol, R.R. Text Book of Ordnance and Gunnery Compiled and Arranged for the Use of Naval Cadets, U.S. Naval Academy (Baltimore MD: Deutsch Lithographing and Printing Co., 1894)

** still more about guncotton . . .

Guncotton in really big guns

The battleship, like the USS North Carolina, has 3 main turrets. The turrets are very heavily armored, with 17 inches of armor. Each turret has three guns, and each gun fires a 16" diameter shell.

The guns are fired with a cordite composition. The powder is kept in 110 pound bags. Three bags are used for every shot. The type of rounds fired are Mark 13 High Capacity Projectile, which weigh 1,900 pounds and carries a high explosive payload. The Mark also weighs 1,900 pounds. Another round is 2,700 pounds and is armor piercing.

Cordite was the result of  the experimentation of  British scientists to produce a reliable  smokeless powder. They found that a mixture of  58% nitroglycerine,  37% gun cotton and 5% mineral jelly produced an effective solution. It was produced in fine strings and given the name  cordite.  This powder did not produce large amounts of fouling or excessive pressures, making it very reliable. 

How to take pictures before digital cameras or Kodak -  a peaceful use for guncotton:

The Wet Collodion Process   Background A difficult process: In the practice of a new and difficult process, the success of which depends on a number of minute details, which, though they admit of variation, require very nice adjustment, there is much room for ingenuity and improvement. Hence, it is of great importance to simplify the process and render it more certain in its results.  My aim will be to detail that process as practised by myself with considerable success and certainty, without reference to the modes adopted by others. The adjustment of the chemical materials to each other is of such importance  that the greatest accuracy is required in their preparation.  All the manipulations of the process also require the greatest care. Prepare Gun Cotton Add the ingredients: Take five and a half ounces of nitrate of potash in powder and add to it in a convenient size bowl ten ounces, by weight, of common commercial sulphuric acid. Stir the whole with a glass rod, and introduce as much finely-carded cotton, about two drachms, as will absorb the mixture and be at the same time thoroughly charged with it. Put a cover on the vessel, and allow the action to go on for five minutes. Then remove the cover, and with a glass rod, poke and separate the fibres of the cotton. The Result: If the action be too intense, which is known by the extreme heat of the surface of the vessel, moderate it by applying a cloth soaked in cold water to its external surface. Then let the cotton be plunged into cold water, and washed so thoroughly that not the slightest trace of acid can be detected.  It should then be dried at a very low temperature, and put past in a bottle for use. Prepare Collodion Mix the ingredients: Take a sulphuric ether 12 ounces;  add to it half an ounce of iodide of potassium, previously dried and bruised in a mortar, and allow it to become saturated by shaking;  then add 6 grains of iodide of silver, shake again to dissolve this, and, after it has become clear, pour it off into another bottle. Next, add about 72 grains of soluble or gun cotton, or, what is better, add as much soluble cotton as you consider sufficient to make a solution so thin as to pour freely over a plate of glass. Then in 12 drams of alcohol dissolve 10 grains of bromide of potassium, and after it is entirely dissolved, add as much iodide of potassium as will saturate the spirit.  The whole of this is to be added to the above solution of gun-cotton in sulphuric acid and well shaken. As I have found a minute quantity of free iodide to be useful in collodion, 2 grains of it  may be added to the above quantity. Use for Negatives of Positives: The preparation now described is especially adapted for negatives.  But for glass positives, it also suits exceedingly well. Coat the Plate Pour the Collodion: The next proceeding is to clean a plate of glass thoroughly, finishing it with a piece of chamois skin or silk, and then to cover one side of it with the prepared collodion, which I do in the following way: I fasten a cylindrical piece of gutta percha to the under side of the glass as a handle; and, holding by this the plate in  my left hand in a level position, I pour on the collodion from a small phial, in a steady and uninterrupted stream, upon the near right-hand corner of the  plate, at the same time altering its level so as to cause the collodion to transverse the whole surface, and then allow  the superfluity to run back into the bottle from the furthest right-hand corner to the plate. Create an even Coating: Next, I immediately give the plate a rotatory motion by means of the gutta percha handle, to render the coating equal, and, after the expiry of from ten to fifteen seconds, according to the temperature, I immerse the plate slantingly in a bath of nitrate of silver, at a strength of 35 grains of the crystallized nitrate to 1 ounce of pure water. I suspend it in this bath for forty seconds without lifting it, and then raise and re-immerse it three or four times at short intervals, or until the solution flows freely over the surface and the solution is free from the streaky and greasy appearance that it has at first. The prepared plate requires now to be dripped for a short time, and then exposed to the image in the camera. Work in a Darkroom: The window of the room in which the plate is rendered sensitive  by the bath, and in which the picture is afterwards to be developed, &c., requires to be covered by a double layer of yellow calico. Expose the Plate The Exposure: The lenses with which the accompanying pictures have been taken are German whole-plate size, and ten inches focus. With a diaphragm of two inches diameter, the plate requires to be exposed from eight to ten seconds, for a negative in summer. If a positive on glass is desired, the plate should be only exposed for a third of the time" [and different development solution used] Portraiture "For portraiture, I invariably use a shady place, so chosen that the main light shall fall on one side of the subject. An awning or roof is placed about three or four feet above the sitter to prevent too much light striking directly on the head. Develop the Plate Process to produce a Negative: After the plate has been exposed in the camera for the requisite time, it is carried back to the operating room to undergo the process of development.  The solution for this purpose is made as follows: - Take     -  Sulphate of peroxide of iron, 480 grains             -  Glacial acetic acid, 1 oz. (fluid)             -  water (common), 8 ounces.  Dissolve. This should be poured expertly over the plate beginning at an unimportant part of the picture, and the plate should be agitated until the image appears sufficiently distinct, and intense to copy form, if a negative is wanted. Process to produce a Positive on Glass: If a positive on glass is desired, the plate should only be exposed for a third part of the time in the camera and should be developed with this solution:                         -  Sulphate of peroxide of iron, 96 grains.             -  Water (common), 8 ounces.             -  Nitric acid, 16 drops. Fix the Plate Fix and Wash: The development  being now completed, the picture must be thoroughly washed, by pouring a stream of water over it; and then it must be secured from the further action of light" [fixed] "and rendered more fit for transferring if a negative, by removing the yellow iodide of silver from the blanks and shadows of the picture. For this purpose I use:             -  Cyanide of potassium (crude cakes), 120 grains             -  Water (common), 8 ounces.  Dissolve. After allowing this solution to remove the whole of the spare iodide of silver, the picture is again submitted to a thorough washing, and allowed to dry spontaneously, by a gentle heat. Varnish: As the collodion is liable to be scratched by the paper or otherwise in copying, it is better to be coated with varnish to prevent this, especially if it is to be frequently copied.  The varnish used for this purpose is comprised of -             -  Gum damar 1.5 or 2 drams.             -  Mineral naphtha, 4 ounces." Intensify (if necessary): After the picture has been fixed, and CAREFULLY washed, from  cyanide of potassium, I pour over it a quantity of the negative developing solution, diluted with an equal bulk of water. Upon this is poured a quantity of a solution of nitrate of silver, in the proportion of 15 grains to 1 ounce of water, and I continue to keep the plate in motion for a time. If the image is made strong enough by a single applicaton, it is well;  but if not, a little more nitrate solution and developing liquid should be applied till the desired pitch is obtained. After this, the plate must be well washed, and again submitted for an instant to the cyanide of potassium, and finally washed  thoroughly. Prepare the Paper Select a Paper: Various kinds of paper are suitable for obtaining copies.  I use almost exclusively a paper manufactured by Pirie and Sons. No. 3 is on a cream-coloured wove paper, made by Cowan of Edinburgh.  No. 1 is on Turner's photographic paper, procured from W & J Milne, Hanover Street, Edinburgh. Coat the Paper: Having got the paper fit for the purpose, the first thing to be done , before applying the blackening agent, is to imbue it with  some of the metallic chlorides. A solution of one salt may be used, or a combination of two or more.  I use a mixture of two  chlorides  -  viz. terchloride of gold and chloride of sodium, of the following strength:                         -  Chloride of sodium, 50 grains.             -  Solution terchloride of gold, 30 drops.             -  Rain water (pure), 20 ounces. The strength of the solution  of terchloride of gold is 15 grains of the crystallized chloride to 4 drams of distilled water. The solution being put into a shallow dish of a size suitable fro the sheets of paper, they are taken one at a time by two adjacent corners, and are slowly drawn through the solution, fires one way then the other. They are then pinned by one corner on a wooden screen to dry. Render the paper Sensitive to Light: Taking a piece of the paper, and driving off any dampness it may have contracted by slightly warming it, I then proceed, with a glass rod or a pellet of cotton, to coat its surface with ammonio-nitrate of silver as evenly as possible, and then dry it quickly by holding it to the fire or pinning it up in a dry, darkish place." "It is advisable to use the sheet as soon as possible after it has been prepared. Expose the Paper Ammonio-nitrate of Silver: The ammonio-nitrate of silver is made as follows: -             -  Nitrate of silver (crystallized), 110 grains.             -  Rain water (pure), 3 ounces. Shake till all the crystals ae dissolved, and then add liquor ammoniae (fortissimus) in small quantities till the precipitate at first formed is almost entirely redissolved."   Should too much ammonia be added, a few crystals of nitrate of silver will bring back the turbidity, in which condition I find it most suitable The frame used for Exposure: The pressure frame I use is of the simplest construction.  It consists merely of a cross-haired flat board, to which is attached by hinges a frame containing a square of plate glass; the pressure being given by a pinching screw. When the  negative and sensitive sheet of paper underneath have been exposed to the action of the sun's rays long enough to make the copy a shade or two darker than is intended to be when finished. Fix the Image The Fixing Solution: When the  negative and sensitive sheet of paper underneath have been exposed to the action of the sun's rays long enough to make the copy a shade or two darker than is intended to be when finished, the copy should be immersed as soon as possible into a bath of hyposulphite of soda to prevent the light from exerting any further influence upon it, or as it is termed, to fix it. The bath is made thus: -             -  Hyposulphite of soda, 2 ounces.             -  Water (common), 16 ounces. To render this bath, from the first, capable of giving tints equal to an old bath, there should be added a dram or half a dram of chloride of silver, and 40 drops of chloride of gold solution, of a strength already mentioned. Fix for 10 Minutes or 10 hours: Those pictures which were from the first rather faint, will be fixed after ten minutes' immersion; and darker ones may be allowed to remain for as many hours, or until they assume the desired gradation of light and shadow. The pictures must then be subjected to thorough washing, so as to remove completely all traces of the hyposulphite of soda bath, which will otherwise be pernicious to the permanence of the colours of the photograph. The copies are then dried; and pressed or polished on the back.        by Thomas Rodger