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History and Manufacture of Leather

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Earliest authentic historical records go back nearly 5000 years. From the carved stone tablets left by the Egyptians of those times, we learn that these people knew about leather and valued it highly. They even considered it to be worthy of tribute to their kings and gods.

Leather articles, found in Egyptian tombs, known to be over 3000 years old, were perfectly preserved. There are numerous references to leather in the Bible. The legends and tales of the ancient Greeks and Romans contain frequent references to leather. At one time among the ancient Romans leather was used as the basis for their money. From the Latin word "pecus" which means "hide", we get our word "pecuniary."

The first American explorers found that the Indians were quite skillful in the art of tanning leather. It. is not known just how or when they gained their knowledge and skill. The work was done chiefly by the squaws. Different tribes used different methods in preparing the leather. They were especially skillful in making buckskin. This type of leather has never been equaled for its softness or ability to turn water.

Leather workers were found among the earliest American colonists. The ancient Hebrews had developed the method of tanning leather by the use of oak bark. No improvements were made in this method of tanning leather until the latter part of the eighteenth century. About this time people learned that oak bark was not the only source of the tanning materials. They found that the bark of very important to the American leather worker since hemlock trees were plentiful in the new country.

Along toward the end of the nineteenth century, an American chemist discovered that chromium salts acting on hides produced a leather different from that produced by the bark tanning method. Other experiments proved that it was necessary for this new type of leather to be treated with soaps and oils.

Thus our modern method of chrome tanning of leather was developed. This new method soon became the chief way of producing leather.

During the same period of time, different machines which greatly changed the methods of working with leather were invented by Americans.

These machines made it possible for one man to do many times the amount of work he could formerly do by hand. Perhaps the most important machine was one that would split the leather to any desired thickness, thus making available at least twice the amount of usable leather. Other machines took care of the de-hairing, fleshing, and cleaning.

As far as the leather worker is concerned, pelts of animals fall into three classifications:

(1) hides which come from large animals, such as cows, (2) kips which come from undersized animals of the same group, and (3) skins which come from small animals, such as calves, goats, and sheep. Pelts which are sent to the tanner must be treated in some way to prevent their decomposition. This is usually done by salting or drying them. The tanner does not find the dried pelts so easily worked as those which have been salted.

Pelts entering a tannery go through a great number of different steps or processes. In brief, they are first soaked in either clear water or a weak chemical solution. This removes dirt, blood, and salt, and makes them pliable. Next, they must be treated in such a way that the hair will be loosened. This is generally done by immersing the pelts in a mixture of lime and water and leaving them there for a certain period of time. The pelts are then removed and de-haired, either by hand or by machine. Next, the fatty material must be removed from the under side. This is usually done by a machine.

Following the fleshing process the pelts must be delimed. This is done by washing and rewashing them in running water to remove the surface lime. If complete deliming is desired, they are placed in an acid solution. After the pelts have been delimed, they are ready for the actual tanning process.

In vegetable tanning the pelts are hung on sticks and immersed in vats containing water and extracts from hemlock, oak, sumac, or various other plant materials. The liquid is made stronger each day by the addition of more tanning extracts until the skins are thoroughly tanned. In chrome, or chemical, tanning the pelts are immersed in solutions of water and common salt and acids to open up the pores of the skins. Then, when the chrome salts are added, they can penetrate rapidly and completely, thus producing chrome tanned leather.

Months are often required to tan the leather by the vegetable method, but only a few hours are needed for the chrome process. After coming from the various tanning solutions, the leather must be washed and pressed to smooth it out.

Splitting of the leather is usually done at this stage. This is done on a machine which has a horizontal blade against which the leather is drawn by rollers. The machine is so accurate that the splits do not vary 1/500 of an inch.

Splitting is done in order to change thick leathers to thicknesses that are suitable for use in shoe uppers, upholstery, and leathercraft.

The outside of the leather is called the grain side and the inside is called the flesh side. Splits near the grain side are stronger and better than those from the flesh side. Oils, soaps, and greases must be worked into the leather to keep it soft and pliable. The leather is then ready for the finishing processes, such as polishing.

At the present time leather is polished by several methods. In one method the leather is first sponged with a special preparation. It is then rubbed with a glass roller under great pressure. If a high polish is not desired, the leather is polished by roller brushes. Leathers may be dyed in several ways: (1) brushing dye on the surface, several coats usually being given, (2) dipping, and (3) spraying. The dyes most commonly used are coal tar dyes. Fancy or embossed leathers are often used in leathercraft. These have been embossed by stamping designs on the hides or skins by means of etched or engraved plates or rollers.

These embossed leathers are generally imitations of more expensive leathers. Suedes are formed by holding the flesh side of the leather against an emery wheel. This produces the nap or fine pile characteristic of suedes.

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