feature By: Leo Remiger | August, 19
In the early days, there was a tannery in almost every community. The bark of the oak, chestnut or hemlock was the principle material used in tanning leather. Chemicals and imported materials were, for a long time, unknown. Some sections of the country had no bark and so no tanneries. Between those regions and the ones having tanneries there grew up the practice of exchanging hides for leather.
At one time hemlock leather was by far the largest item of sole leather produced. Owing to its quality and uniformity, American hemlock gained an excellent reputation. This tannage gives the “red” leather, the nearest approximation to which is that tanned with American chestnut oak. This kind of leather lends itself more readily to stitching and nailing than to Goodyear welting.
The local population procured their shoes of the local shoemaker, who obtained his hides from the village tannery. Farmers often had their own shoes made at the local tannery from hides which they had tanned “on halves” that is, the tanner had one-half the finished product.
The discovery of the process of extracting the tanning properties of bark caused the industry to expand into regions that had no tan bark. The development of splitting hides and of coloring leather, both of which were considered improvements at the time, were adopted by the larger tanneries, popularized their product and caused the number of small tanneries to diminish. Some of them continued for a time, making rough leather and furnishing it to the larger concerns. The latter gradually reduced the costs and drove the greater number of the neighborhood tanneries out of existence. In 1849, there were 6,686 separate tanning establishments. In 1919, there were less than 700.1
THE PRINCIPAL OF TANNING
1st Lt. D.A. Lyle, Ordnance Department, United States Army, Benicia Arsenal, California, authored Appendix K, “Manufacture of Leather” to the Annual Report of the Chief of Ordnance to the Secretary of War for the Fiscal Year Ended June 30, 1878. In Appendix K 1st Lt. Lyle wrote: “The Principle of Tanning. This may be stated as follows: Take the skin of an animal, remove from it the hair, fat, loose flesh and other impurities, and immerse it in a dilute solution of tannic acid; the cellular and elastic tissues will gradually combine with that substance, as it penetrates toward the interior, and will form a compound perfectly insoluble, and which will completely resist putrefaction; this compound is leather.”
On the buffalo range, classification of buffalo hides was pretty straight foreword. “Bulls”, “Cows”, “Kips”, “Damaged”, “Missing” and “Stolen” were just about the extent of the classifications needed. These buffalo hides were then either baled on the range or hauled to hide yards where they were baled and shipped to tanneries in the East or overseas.
Upon receipt at the tanneries and prior to tanning, hides were normally divided into classes. “Slaughtered” hides, meaning those fresh from the slaughter house, “salted” hides (sometimes called “wet” hides), or those which have been salted in order to preserve them from putrefaction until they reach the hands of the tanner and “dry” or “flint” hides; this last category would include hides that were pegged out and allowed to dry or cure in the air, folded in two, baled and shipped to the tanner. West coast tanners stated that leather made from “slaughtered” and “salted” hides more easily and quickly tanned, it also made better and smoother leather than “dry” hides.
In order to produce tanned hides that were uniform in weight, substance and condition the hides had to be sorted prior to tanning. A careful examination of the hides was required before sending them to the lime-vats and this examination was repeated after each operation. If the hides in a single pack varied too much, then the tanning operation would not be uniform. This was especially true if “slaughtered,” “salted” or “flint” hides were mixed into the same lot, or if bull, cow and kip hides were in the same lot ‑ this was a real problem for the smaller tanneries.
At the meeting of the National Convention of Tanners and Dealers in Hides and Leather, held at the Centennial Exhibition in Philadelphia, in October, 1876, the following rules were unanimously adopted for the object of securing a uniform method of classifying hides. It was stated that, “These rules will control the action of the whole trade until otherwise ordered.”
RULES FOR THE CLASSIFICATION OF HIDES:
RULE 1. All Hides having one or more grubs shall be thrown out and classed as damaged.
RULE 2. All hides and skins cut and scored on the flesh side shall be thrown out and classed as damaged.
RULE 3. All hides for currying purposes having one or more brands shall be thrown out and classed as No. 2 hides.
RULE 4. All hides sold for sole leather having more than one brand shall be thrown out and classed as No. 2 hides.
RULE 5. All harness hides visibly damaged by hook or horn marks on the grain shall be classed as No. 2 harness hides.
RULE 6. In the vocabulary of this trade, one letter, figure, or mark constitutes a brand on a hide, and cattle-raisers, in their own interest, are requested to make their brands of one letter or mark, as small as possible, and so located upon and down the leg as to produce the least possible injury to the hide.
RULE 7. The above rules concerning cuts, scores, grubs, and brands shall be applied to all transactions in dried hides as well as to those that are fresh or salted; also to imported as well as to domestic hides.
RULE 8. All calfskins shall have the sinews taken out, or proper tare allowed for the same; the minimum weight of untrimmed skins shall be 8 pounds and the maximum weight shall be 15 pounds. This classification to be applied strictly to calfskins, with no application to long-hair summer kips, which shall not be considered calfskins. Trimmed calfskins, with heads off, shall be 1½ pounds less weight; veal-kips shall be classed as plump; milk-calfskins, 15 to 25 pounds, in the season shall be classed as short-hair kip.
RULE 9. A green-trimmed hide is a hide clear of horns, bones of all kinds, flesh, sinews, blood, manure, or other offal.
RULE 10. Green-salted hides shall be considered in good merchantable condition when the same are fully cured or preserved with salt, and well cured of their animal juices, and free from all salt and superfluous wet in the hair or on the flesh, or so made by proper tare, when bought and sold.
RULE 11. Any watered hide, or one which has any material put upon it except salt, for strictly curing purposes, shall not be considered in a merchantable condition, and all sales of hides made in such condition shall be considered fraudulent, unless the condition be made known to the purchaser previous to the sale.
RULE 12. Hides cut at the throat shall be classed as unmerchantable, provided the gash extends more than one-fourth across the hide.
Regardless of geographical area, be it West Coast, East Coast, North America, South America, Europe, or the Far East, the tanning process was basically similar. The procedures and components varied, but the final product was leather – regardless of the use it was put to. We are primarily concerned with the leather made from the American Buffalo (“Bison” for you purists). 1st Lt. Lyle wrote: “Imitation buckskin, collar, and sole leather are made from bison hides.” He also wrote, “Bull hides are inferior to either steer or cow hides, making a thick, spongy leather.”
When the hides reached a tanning establishment, regardless whether “slaughtered,” “salted,” “flint,” “cow,” “calf” or “bull,” they were brought to what was called the “beam-house” or something similar. They were soaked in vats filled with soft water for approximately three days, to soften them and to dissolve and remove any debris as well as salt. The hides were then placed in vats (an example being a seven-foot by eight-foot by five-foot vat) containing “milk of lime” (quick-lime, slightly air-slacked, and water) where they would remain for approximately nine days.
A common problem with the lime-vats was the lime caused the thin parts of the hides to contract more than the thick. The hides were seldom cut in two halves until after the liming, because an irregular back line will be the result which will in turn lead to loss in cutting where long strips are required. This is especially important in belting and harness leather. The lime loosens the hair, saponifies the fat, and distends the fiber. Some contend that the lime carries off the gelatine and albumen of the skin. High-limed leather is loose in texture, light weight and wears out rapidly. Subsequent fermentation in the bate, after liming, increases this problem.
The hides were then taken from the lime-vats after the nine days and “beamed.” The beaming operation removed the hair, flesh, dirt with a fleshing knife. The “beam” was made of thick planks, semi-cylindrical in shape, with its axis making an angle of about 45 degrees with the floor; the convex side was uppermost, and the higher end, against which the workman held the skin by pressing against it with his body and legs while he manipulates it. After being scraped and fleshed upon the beam, the skins were trimmed. The refuse trimmed off was barreled and sold to glue factories for glue stock. The hair was washed, dried, sacked and sold; examples of use include a component of plaster, stuffing in carriage upholstery and even pillows and mattresses.
At this point the hides are divided into three classes:
• 1st Class: The heaviest, thickest and best hides were selected for sole leather.
• 2nd Class: These hides are selected for size, uniform thickness, and if cattle hides, freedom from brand marks, gashes or holes. These hides were destined to be made into harness-leather.
• 3rd Class: Light leather, all those hides not previously selected for 1st or 2nd class use.
The 2nd Class hides, which were selected for harness-leather, are then milled in clean soft water for about fifteen minutes to remove the lime and to soften them. They are then bated in a solution of hen-manure. This lixivium, or bate, is made by putting one bushel of hen-manure in vats half-filled with cold, soft water. The manure vats are eight-foot by five-foot by four-foot in dimension and will contain 50 hides or 100 sides, if the hides were cut in half during the initial beaming operation. The vats are cleaned and fresh liquor put in once every two months. In moderately warm weather the hides are left in these for one or two days; in cool weather, more time is required. On removal from the manure vats the hides are washed, stoned and “worked over” which consists of scraping both sides of the hide very carefully on beams. The second beaming is to remove all short hairs (new growth), earth, and lime leaving the hides soft, pliant and ready for the absorption of the tanning solution.
The 1st Class hides, which were selected for sole leather, were never milled or bated, but simply washed with cold water and stoned.
The next stage is the Tannery
Tanning: The hides from the beam-house are placed on stringers (or vats of 9 by 8 by 5 foot dimension) and tied up so they hung lengthwise in the pits. Approximately seventy sides (if the hides were cut in two at the beam house) are put in each vat. There they hung in a weak ooze or infusion of oak-bark for seven days after which they are then “handled” daily for another five days. “Handling” meant the hides were taken out of the vat and into the air, smoothing them out, sometimes rubbing them to remove ridges and wrinkles and returning them to their former position on the stringer. Each day they were handled, the strength of the infusion increased a little.
Layers: The hides are then ready to be put in the layers or lay-aways, so called because the hides are laid away for some time. There are four of these large vats, designated as the first, second, third and fourth layers.
For the first layer thin stratum of ground oak bark is spread over the bottom of the vat for the first layer and upon this a hide is laid flat, with the flesh side down and covered with a layer of ground bark, upon which a second hide is placed and so on until the vat is filled. A thick stratum of oak bark is spread over the top and a weak tan-liquor is pumped in until the vat is full. If the vat already contains the ooze, a stratum of dry, pulverized bark is strewn upon the surface of the liquor, a hide placed upon this, then a second layer of bark and another hide and so on, until the whole sinks and the vat is full. If the mass does not sink, it is trodden down by the feet of a workman. The flesh side is always placed downward to avoid scratching the grain when removing the hide from the vat with the necessary hooks. The hides remain in the vat for approximately eight days.
Up to this point the operations were essentially the same for all three classes of hides (sole, harness and light leather). From this stage, they differ somewhat depending on the ultimate use of the hide.
Sole leather, a common category for buffalo hides destined to become belting leather, progressed to the second layer. The hides were put into the second layer vats in the same manner as the first yayer. This second layer included a strong infusion of bark-liquor and the hides remained in the second layer vats for eighteen days. After that time period, they were removed from the second layer and progressed to the third layer and placed in the vats in the same manner. A very strong liquor filled the vats and the hides remained there for twenty-five days. After being removed from the third layer the hides progressed to the fourth layer. They were laid down into the vats in the same manner as previously, but the bark liquor was the strongest solution that could be made at that time. In addition to the bark liquor, a solution was added which was composed of gambier and valonia. The proportions consisted of two pounds of gambier and two pounds of valonia for each hide. The hides remained in this solution for four weeks. When the hides were removed from the fourth layer the tanning was complete.
After tanning the leather went to the currying shop. Here sole leather was soaked in a weak solution of tan-liquor for twenty-four hours. The object of this soaking was to remove, from the surface of the hides, a little of the strong tanning material previously absorbed in the vats of the fourth layer. This caused the hides to become a little lighter in color – buyers preferring light, bright-tinted hides. When the soaking was completed, the hides were then vigorously washed with soft water via the scrubbing motion of brooms. The hides were then hung up for two days under cover to allow the water to drain off. In order to keep the light color the buyers preferred, it was necessary that the hides be kept in a dark room and free from currents of air as the slightest air current turned the hides a deep brown color when they were initially removed from the tan-vats.
The hides were then treated to a coat of polar oil, applied with a brush or swab and hung to dry in a cold, dark, close room for eight days. When dry, the hides were taken down, sprinkled with water and piled in the rolling-room for twenty-four hours to dry. The next step consisted of the hides being rolled under great pressure by a brass roller driven by steam-power, after which they were again hung up for twelve hours to dry. When dry, they were taken down, and either the weight was stamped upon each hide or they are put up in rolls of ten sides (if cut in two in the beam house) and the total weight stamped upon the rolls. The total time occupied in preparing sole leather for market was 117 days from the date the green hides entered the beam house.2
Hides destined to become belting leather were processed essentially as mentioned above. The hides were tanned with vegetable materials, either bark or extracts. The leading kinds of sole leather are oak, hemlock, and union. The union tanning process simply combines oak, chestnut oak, and hemlock in the tanning process. Quebracho was also used in combination with other materials in tanning belting and sole leather. However, oak was the leading material used in tanning belting leather.
Over the years many steps were taken to improve and speed the process of tanning, probably one of the most important being the adoption of drum tanning. This process used large drums to force the tannin into the hides and reduced the time required for tanning from several months to six or eight weeks instead.
Because belting leather must have greater flexibility than sole leather, the fibers of the hide were not so thoroughly filled with tannin. After the tanning process had been completed, the belting leather was thoroughly filled with grease or dubbin. Each bend (portion of the hide from the back) is then cut into bands, which are stretched before they are made up into belting.
The illustration above shows the points of a typical hide:
• A is known variously as the belly or belly offal.
• B is inside the dashed lines, and is known as the butt. The butt can include the area of B and C and in some cases, B to the dashed line at the base of D.
• C is the area encompassing the bottom dashed line of C to the upper dashed line of D is called the shoulder.
• D is called variously cheeks or faces.
The dotted line down the center of the hide is called the ridge or the back.
When the hide is split down the middle of the ridge, the two pieces are called the bend or sides.
If the area between B and C is cut off – it is known as the range.
If the area between B and C is cut off and includes D it can be called a “shoulder with cheeks and faces.”
The manner of cutting the hide depended on the spread and size of the hide. The part of the hides that were used to manufacture the best belting are shown in the next illustration. Characteristics of the various parts are marked. The piece enclosed by the dotted lines is that employed in the manufacture of the most common belting, while that enclosed by the full lines B, C and D is used for the very best belting. The former includes the shoulder, which is more soft and spongy and it contains numerous creases as shown. These creases are plainly visible in the belt when made up, and may be looked for near the belt joints.
The center of the length of the hide will stretch the least, and the outer edges on each side of the length of the hide the most. Thus, the only strip of leather in the whole hide that will have an equal amount of stretch on each edge is that cut parallel to line A and having that line as the center of its width. All the remaining strips will have more stretch on one edge than on the other. To obtain the best results the leather should be stretched after it is cut into strips and not as a whole hide, or that part of the hide employed for the belt strips. It was found that even though stretched in strips, the leather was apt to curve in time.
Belts that are straight when rolled in the roll, will be found to be curved when unrolled. Each time the width of the strips is reduced, this curving will subsequently take place. For instance, if a belt eight inches wide and quite straight is reduced to two belts of four inches wide, they will probably curve after a short time. The reason is because the edge of the belt nearest to the ridge offers the greatest resistance to stretching.
However, this was not found to be of great importance so long as the outer curve is on the same side as the adjoining segment when they are joined to form a belt. If that principle is followed – the belt will run straight and true on the pulley; if not, the belt will run crooked and wobble from side to side on the pulley.3
A single belt is one composed of a single thickness of leather put together to form the necessary length. A double belt is composed of two thicknesses of leather cemented and stitched, sewn, riveted or pegged and often with a heavy canvas sandwiched and cemented between the two leather sides. The object of a double belt is to increase the strength without increasing the width of the belt.
In 1889 it was said, the largest leather belt in existence was manufactured by the Bradford Belting Company, Cincinnati, Ohio, for the People’s Electric Light and Power Company of Jersey City. This belt lacked four inches of being seven feet wide and was 165 feet long. The big belt was made of three thicknesses and in making the entire belt there was not a single rivet, peg, or stitch used, it being glued together by a kind of cement made by the Cincinnati company according to a secret recipe. The 432 steers whose hides made the belt, when alive would fill twenty-four cattle cars with eighteen steers in each car. The twenty-four cattle cars, when placed in a line, would reach three-quarters of a mile.4
As the tanneries became more mechanized, some of the procedures were accomplished by machines. For instance, scouring machines were designed to do a lot of the work that was accomplished in the beam house. A machine in use by T. Haley & Co. at the West Grove Mill in Halifax consisted of a large table which could be moved transversely. Above it a beam supported a framework holding a series of brushes. The brushes moved rapidly backwards and forwards over the hides on the table while water carried away any dirt, hair, flesh and other matter that the brushes scoured off the hide. The machine was capable of doing the work of six men.
T. Haley & Co. used wire-stitching machines to sew their double belts in 1885. The machine was based on White’s Patent – the wire was supplied to it continuously from a drum, but at a point near where the stitching takes place the machine cuts the wire so that each stitch is single, and not one of a series. They had one machine capable of stitching a double belt eighty inches wide! They advertised single and double belts in any length with some of their rolls containing five hundred feet of double belting.5
Go back and look at the illustration of the buffalo hide, showing how belting strips were cut from the hide. Can you imagine how many hides it took to make that roll of double belting if it was eighty inches wide and five hundred feet long?
1. “Tariff Information Survey – Belting and Sole Leather – Summary,” United States Tariff Commission, Government Printing Office, Washington D.C., 1922, “,” pp 7-26
2. Lyle, 1st Lt. D.A., “Appendix K, “Manufacture of Leather,” Annual Report of the Chief of Ordnance to the Secretary of War for the Fiscal Year Ended June 30, 1878, Government Printing Office, Washington, 1878, pp 61-87
3. Rose, Joshua, “Modern Machine Shop Practice – Volume II,” Charles Scribner’s Sons, New York, 1892, pp 207-216
4. The Leather Manufacturer, Vol IX, Number 7, July 1898, Boston and New York, 1898 Page 109
5. “Merchants and Manufacturers at Home – No 1 – Thomas Fleming and Son”, The Merchant and Manufacturer, Vol. VII, No. 139, September 15, 1885, pp 272-273.