Learn more about the tanning process involved in leather making here.

WHAT IS TANNING

Leather is made from animal skins or hides which have been chemically treated to preserve quality and natural beauty. The chemical procedure used to ready raw animal hides for use is called “tanning.” A piece of hide or skin which has been tanned produces a strong, flexible leather which is able to resist decay and spoilage.

The majority of leather made today is produced from tanned cattle hides, though many types of hides can be used, including those from horses, pigs, goats, calves, labs, deer, kangaroos, reptiles, seals, and walrus.
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DELIMING

After the hair and debris has been cleaned from the skin, hides are delimed in a vat of acid. After the lime has been pulled from the skin, hides are treated with enzymes, which smooth the grain of the leather and help to make the resulting product soft and flexible.

TANNING

Hides and skins are often treated several times during the process of tanning. Which type of tanning procedure is used, depends largely on the hide itself and the resulting product intended.

VEGETABLE TANNING

Hides which have been tanned with a vegetable tanning agent solution produce flexible, but stiff leathers, such as those used in luggage, furniture, leashes, belts, hats, and harnesses.

Vegetable tanning consists of stringing hides on large frames, located inside large vats, and exposing them to tannin, a natural product found in the bark, wood, leaves and fruits of chestnut, oak and hemlock trees. Hides are transferred to many different bins during this step, each containing a stronger solution of tannin. Vegetable tanning prevents the skin from decay and shrinkage.
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Leather Industry Glossary (U-Z)

Leather Industry Glossary - A collection of frequently used terms, abbreviations and jargons used in the Leather Industry with their definition and meanings.

Vacuum Drying:
A method of drying leather taking advantage of the fact that moisture evaporates more quickly under vacuum. The wet leather is laid out on a wet steel plate (often slicked, a form of hand setting out) and the vacuum head brought down. After retanning and fatliquoring the leather can be dried to either 30% and then hang dried or in some circumstances fully dried direct. Drying only takes two to five minutes. A newer use of vacuum drying involves using a rubber base instead of stainless steel. While the leather is under vacuum this rubber base expands outwards, stretching the leather out from its centre. I have seen a page of newspaper pulled into jigsaw-sized pieces by this machine. It is not so good for taking out large amounts of moisture but good for the drying after conditioning and staking of soft leathers. Avoid using it just for area gain.

Vellum:
Vellum is practically the same thing as parchment but is made of calfskin. The word is derived from the Latin vitulus, a calf, whence our word veal. Drum leather is a specialised form variety of vellum, made nowadays in diminished quantities for the purpose indicated by its name. (11)

Wet Blue:
Chrome tanned leather. Chrome tanning creates a blue colour in the leather and there is a natural safe resting stage just after tanning when the leather is both wet and blue. A significant stage in which leather is traded semi-processed worldwide.

Wet White:
Hides and skins with the hair or wool removed and preserved after a light aluminium tannage. More stable than pickle. Increasingly used as an intermediate stage for transporting and selling hides and skins.

Leather Industry Glossary (S-T)

Leather Industry Glossary - A collection of frequently used terms, abbreviations and jargons used in the Leather Industry with their definition and meanings.

Santa Croce..
….. Igualada, Vic, Alcanena, Solofra, Lyon, Arzignano, Guadalajara, Kano, Northampton, Ambur, Ranipet, Vaniyambada, Millau, Kano, Graulhet, Mazamet, Gloversville Some of the places in the world which are centres for the leather industry

Samm, sammying:
The mechanical extraction of moisture from leather after a processing stage. Most normally done on wet blue after chrome tanning, using a machine which carries the leather through felts.

Scud:
A film or deposit of waste matter appearing on the surface of leather in process after certain operations, esp. bating.
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Leather Industry Glossary (Q-R)

Leather Industry Glossary - A collection of frequently used terms, abbreviations and jargons used in the Leather Industry with their definition and meanings.

Retanning:
A process subsequent to the main tannage when the character of the leather is adjusted by the addition of further alternate types of tanning material. Thus synthetic or vegetable tans may be added to a chrome leather to adjust certain characteristics.

Roans:
Sumac tanned sheepskins.

Rockers:
A device for the continuous agitation of hides when suspended in pits or vats in order to hasten the operation of the liquors.

Rolling:
One of the final operations in the manufacture of sole leather, by which it is given a smooth surface and even thickness.
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Leather Industry Glossary (O-P)

Leather Industry Glossary - A collection of frequently used terms, abbreviations and jargons used in the Leather Industry with their definition and meanings.

Paddles:
A name applied to certain types of machinery with rotating arms, which are used in various tanning operations for agitating hides or skins in process. Use more water than drums, allowing larger floats and consequently gentler action. Mostly used in the soaking and liming areas.

Painting:
A process for loosening hair or wool (usually the latter) which is employed with skins whose protective covering is so valuable as to make it desirable to avoid injuring it by soaking in a lime liquor. The process is carried out by painting the flesh side of a skin with a depilatory substance, containing sodium sulphide or arsenic. Nowadays this is the usual method with sheepskins bearing the higher grades of wool. Before it was invented, such skins were usually dehaired by sweating.

Parchment:
Town near Izmir (Smyrna) in Asia Minor. Parchment (from Latin “carta Pergamena”) supposedly first made there in 3rd cent BC. When the King of Pergamus was building a great library in rivalry with the library of the King of Egypt in Alexandria, the latter placed an embargo on the exportation of papyrus from Egypt to hamper competition. The King of Pergamus thereupon perfected the manufacture of parchment for the making of books.
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Leather Industry Glossary (K-L)

Leather Industry Glossary - A collection of frequently used terms, abbreviations and jargons used in the Leather Industry with their definition and meanings.

Larrigan Leather:
An American speciality made of light cattle hide and used in the manufacture of the heavy moccasins worn by lumbermen to guard against slipping when walking on wet logs.

Latigo Leather:
The Spanish word latigo means a whiplash and this leather was originally tanned for that purpose; but as a technical term in the present day American trade, latigo means the straps used for cinching saddles of the McClellan, cowboy and Mexican types. This leather is usually prepared from cattlehides by a combination tannage.

Layers:
The last set of vats or pits in which heavy leather is tanned, containing the strongest liquor. The hides in these pits are laid flat - originally with layers of tan bark between them.
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Leather Industry Glossary (I-J)

Leather Industry Glossary - A collection of frequently used terms, abbreviations and jargons used in the Leather Industry with their definition and meanings.

In the hair; in the wool; in the raw:
A group of more or less equivalent terms used to describe stock that has not yet undergone any of the processes of leather manufacture.

In the rough; in the crust; in the white; in the blue:
A group of approximately equivalent terms used to describe stock which has been tanned,, but not finished. In the rough or rough tanned is most commonly applied to vegetable tanned cattle hide leathers; in the crust and in the white to vegetable, alum or formaldehyde tanned sheepskins and lambskins; and in the blue to chrome tanned skins particularly goatskins. The use of the term in the white needs to be distinguished from that mentioned in the following definition. See also Wet White and Wet Blue.

In the white; in the pickle:
Two roughly equivalent terms used to describe stock which has undergone the processes preliminary to tanning, but has not been actually tanned. Historically in the pickle is restricted to sheepskins and lambskins; in the white, in this sense, is used for practically all other classes of hides and skins.

Japanning:
A process of preparing the oil for, and the process of, manufacturing patent leather.