Stand: 08.06.2023
Leather Information
Leather is a material, that is produced through the process of tanning from hides and furs, preserving its natural grown fibers and interwoven properties.
  • Divisions of a Leather Skin
  • Measuring the area of a hide
  • Tanning Agents
  • Vegetable Tanning
  • History of Leather Production
  • Salting of fresh hides (Salt Conserving)
  • Stations of Leather Fabrication
  • The Leather Purchase
  • Storing Leather
  • Leather Care
  • Milled Leather
  • Craquelé Style
    •
    Parts of the hide
    Leather is a grown material, it doesn't come from a roll, every leather is different, and the area is measured on an average mass of each individual piece. Tolerance levels of ± 30% are therefore normal. Due to this, prices are only relative, for example 39, 00 €/m² is listed. The exact price for a piece is always given separately.

    Aufteilung einer Lederhaut

    Aufteilung einer Lederhaut

    The Croupon/dbl. Bend is the strongest and most valuable piece of the hide.

    The Shoulderpiece is known for its neck rings.

    The Belly has a loose structure. They are not as firm as the croupon.
    Measuring the area of a hide
    Leather is measuredafter its production with the aid of photocells and/or mechanical devices. The area measurement is then imprinted on the back side of the leather either in square meters (m²) or square feet (sq. ft.).
    • 1 m² = 100 dm² = 10,76 qfs (squarefeet)
    • 1 qfs = 0,0929 m²  =  30,48 cm x 30,48 cm
    Tanning Agents
    Tanning Agents are applied to preserve the animal hide.
    To satisfy Customer demands or to achieve a certain product, different tanning agents are used.
    There are many different tanning agents. The leather industry generally differentiates between the mineral and vegetable (natural) tanning process.
    Chemically produced tanning agents were developed using qualities of agents found in nature. Because of this technology it is possible to produce the large quantities of agents needed to meet the demands of leather production.

    Chrome Salts
    For over 30 years, 85% of usable leather has been produced utilizing the Chrome Salt method of tanning. Chrome tanned hides are not permanently washable and are not sweat resistant. Today the 3 Stage Chrome Tanning Process is non-hazardous..

    Alum
    Alum- or White Tanning is one of the oldest methods of tanning known. The agent is comprised mostly of Aluminum Sulfate and Sodium Chloride (native salt). Alum tanned hides are not washable and are very rarely produced.

    Relugan GT 50 (Product of BASF AG)
    The agent Relugan GT 50 is a Gluteraldehyde-Tanning Agent and has the special property of giving the finished leather product a permanent wash ability as well as sweat resistant attributes. It softens and expands the leather and stabilizes furs. A special property, the process allows usage in the medical field. Over time it has been given the title: Medical Lamb or Sheep Skin. The leather has a golden color.
    Vegetable Tanning
    Vegetable Leather (botanic tanned leather) are tanned traditionally using the pit method.

    This valuable leather is produced following ecological guidelines and methods. The total life cycle of the product is evaluated and remains constantly in fore field of its production, this stands for resource retention production, long life and environmentally safe producing qualities.

    Lederhaus guaranties, that all vegetable tanned leather are produced utilizing following guidelines:


    Leder bearbeiten - Gerbstoffe

    Botanic Tanning Agents
    • Mimosa: A tree bark tanning agent, found in the black acacia (locust tree) from Australia and Africa, is grown on plantations, with a very high amount of tanning agents.
    • Quebracho: A wood tanning agent, which is also very yielding in tanning agents and is used in many differnt leather types. Quebracho grows in plains with an average daily temperature of 24 - 28 °C .
    • Chestnut Chestnut: A wood tanning agent found in the chestnut from France and Italy.
    • Tara: A fruit tanning agent from the Tara bush that is native to Peru and India, used is the shell of the fruit.

    Absolute chrome free
    Neither chrome tanning agents are used, nor does the product ever come in contact with other leathers containing chrome tanning agents (meant is that containers used in the tanning process are cleaned of all chrome containing residue and other dyeing agents) during its production.

    Abandonment of Softeners
    Gluteraldehyde and other Aldehydes which are used to achieve softness and fill in the finished product are excluded.

    Heavy Metal Dyes
    The utilized dyeing agents are in accordance with the 3. Amendment to the German Consumer Goods Regulations from 16.12.94.

    PCP-free, compostable
    Meets requirements as mentioned in guidelines in the PCP-Prohibitive Order, making it totally compostable.
    Leather types
    The following types of leather can principally be produced from every hide. Whatever leather type is produced depends mainly on the method of production.
    Polished Leather is the classic pure vegetable (botanic agents) and mainly in pit tanned leather. Only Cow Hides (no Bull or other animals) are used. Because of this the result evenly distributed structure (fiber, thickness) over the whole hide. The polished leather has a smaller fat content from 5 - 11%; it is not as soft as garment leather.

    Nubuk has a soft, open pored surface which is velvety and feels slightly rubbed. It appears either lighter or darker when one rubs it with the hand.

    Aniline with its soft, almost skin like surface and its transparent protective coat has a very pleasant touch. Every pore is visible and touchable, very high end leather and from appearance very rich and satiny, washable.

    Semi-Aniline lies between Anilin and Nappa, the qualities of both leather types are unified.

    Nappa is also known as smooth leather (see also Upholstery Leather). The surface is finished, the pores are therefore closed. Often the structure is assisted through embossing. Big plus: is good against moisture and soiling.

    Velour/Suede is also known as "Wild Leather". Very appealing due to its long fibered surface soft to the hand touch.

    Full Grain Leather is un-split thick leather with both leather parties' intact, grain side and flesh side.
    History of Leather Production
    Animal Skins and Furs have been prepared prior to civilization and with primitive methods (for example clothing) and so made useful.
    Preparing animal skins to leather with the addition of tanning agents pre-dates the Stone Age man (ca.8000 BC). It is evident that the form of fat tanning (Chamois Method) was done in the Neolithic period (ca.6000 BC). Also smoke tanning over fire and the mineral tanning with alum (White Tanning) are surely ancient tanning methods. Tanning with botanic agents (Vegetable Tanning) is known since the Bronze Age (ca.2000 BC), where mainly the bark of the oak and beech as tanning agents were used. This tanning method (Bark Tanning) was traditionally used during the medieval period. Out of these basics and through increasing civilization and knowledge a craft and industry has emerged.

    Since 1900 Chrome Tanning with Chrome Salts is the most important tanning method, due to the shorter time requirement necessary compared to the Bark Tanning method which can last up to 15 months.
    After the tanning process and prior to dyeing the leather one can determine the tanning method based on the color of the leather.
    Bark Tanning is brown, Chamois Method is yellowish, Alum is almost white and the Chrome Method is silver grey.

    Special tanning methods and finishes prepare the leather for product manufacturing depending on what its final use is to be. Shoe soles for example require other attributes as would leather for furniture, garments, gloves, book bindings or small leather goods.
    Salting of fresh hides (Salt Conserving)
    Fresh skinned hides can be preserved with salt. This is a typical method for conserving hides before the tanning process which may occur due to long transport distances or if the raw hides must wait before being delivered to the tannery.
    Important: Early after skinning and cooling of the hide the skin is coated on the flesh side 25-50% of its own weight in native salt. The salt removes water, conserves the hide and kills bacteria. This allows the raw hide to be stored in a cool place for a number of days. Note: not enough salt is worse than no salt at all.
    Stations of Leather Fabrication
    The Leather production is a complex technological process which is achieved through a number of steps.

    Storing and Sorting

    The conserved raw goods are stored in a cool place; quality is proofed and sorted prior to the production.
    Soaking

    Through the softening the raw hides are freed from dirt and salts.

    Fleshing

    This step in the process removes fat deposits and meat deposits still remaining on the hide. The hides are drawn through a stripping machine.

    Traditional fleshing is done with a fleshing knife and a radial fleshing beam.

    entfleischen auf dem Gerberbaum
    Hair Removal

    Soaked and worked in vats, with the addition of calcium and sulphur the hair is loosened and removed. Scudding is still performed by hand to remove any leftover fur in the hide.
    Deliming, Pickling and Tanning

    Deliming and pickling introduce acids and salts into the hide to prepare for the hide for tanning. During the tanning the hide fibers absorb the tanning agents and the hide is now leather.
    Rolling

    The wet leathers are then pressed through large rollers extracting the water and moisture from the hides.
    Splitting
    To achieve an even and proportionate thickness in the leather it is drawn through a machine with a revolving knife which splits the upper leather or grain from the flesh or under leather. Comparable to the principal of a band saw.

    Upper Leather/Grain Leather
    The grain side is then brought to proper thickness and is then ready for the saddler, upholsterer or bag maker. By thick leathers are all layers of the hide still present. These leathers were used throughout history in the area of protection. Additionally grain leathers find usage in the garment and upholstery industry.

    Split Leather
    The flesh side has a lesser tear resistance and is made into velour/suede, wild leather, or to other heavily finished plain leathers.
    Folding

    The grain leather is worked to a unified thickness. Uneven areas on the flesh side are removed. In closing this step the leather is then separated to individual dyeing pieces.
    Neutralizing, Filling, Dyeing and Oiling

    In this stage the remaining acids from the tanning process are neutralized. Following and according to the leather types the filling and dyeing with leather dyes. Through the additive of oils the leather achieves the necessary softness.
    Drying

    Two methods of drying the leather are administered: Vacuum drying, in that the moisture is sucked up and the Hang Drying whereby the leather is suspended and runs through a drying oven.
    Conditioning

    To get the leather back into a soft state after the drying process it is machine conditioned and additional steps to prepare it for the finishing process.
    Finishing
    After the tanning process the leather is still not useful. There are still quite a few steps which it must undergo depending on type of leather and application. All steps which transpire after the tanning is what is referred to as finishing.

    Finishing achieves the following:
    A.  Protection of the leather surface against chemical and mechanical influence.
    B.  Evening the color and polishing over the whole surface.
    C.  Special optical and touchable elements.
    D. Increasing the value of the leather.

    Through these final finishing steps the leathers surface achieves its final appearance. Through buffing, dyeing, sanding, pressing and ironing the leather depending on its purpose either becomes a glossy, matt, embossed or natural grained, uniform color or multi colored surface.
    The art of leather finishing consists of administering thin coats on the surface without diminishing the natural optic and attributes of the leather, like suppleness, and breathe ability.
    Control

    The quality is governed between every step of the tanning process. The final control proves that the individual steps have met the standards required so as to qualify for the type of leather produced as well as meeting standards as described in the master pattern. Here the leather is sorted as to value grades.
    Measuring, Packing

    The leather is now electronically measured, packed and ready for sale.
    The Leather Purchase
    Our leather originates in Germany as well as companies that meet all legal ordinances. During our purchase of all kind of leather we consider the used technology of production
    Quality Guidelines

    • PCP - Levels max. 5 mg/Kg according to the Pentachlorophenol Ordinance of FRD.
    • No Chrome-VI Levels.
    • No AZO-Coloring Agents according to the 3. Amendment of the German Consumer Goods Regulations from 16.12.94.
    • By natural leathers that discoloring cannot be excluded.
    • Automobile Leather, Motorcycle Leather and Upholstery Leather meet all standards in non-fading properties,
      fastness to rubbing and constant bending properties as prescribed in German Industry Norm.
    • Vegetable Leather only uses natural botanic agents in the tanning process.
    Storing Leather
    An important attribute in leather is its elasticity, suppleness and bend ability, required for this is the proper moisture content within the leather. It is therefore pertinent that the leather be stored properly
    This should take place in a cool, not too dry, ventilated area where a temperature between 10° - 15° C with a relative humidity level of 50 - 75 % is given. If the moisture level sinks too much the leather becomes brittle and harder. By too much moisture the leather could possibly become mould stains or mildew.
    Removal of Mildew Stains: Dry brush and rub with a disinfecting agent.
    Also direct sunlight should be avoided, the danger of fading or fat staining is possible.
    A proper storing can be achieved in cabinets or shelves, whereby the bottom most shelf at least 10cm from the floor is and the leather is not stacked higher than 1m.
    Leather Care
    The purpose of proper leather care is to assure the attributes associated with leather in use maintain a long life span.
    One speaks of two groups or types of leather care:

    a) Surface Care
    Leather articles and shoes are cared for with crèmes and wax lotions, this is atypical surface care. These products beautify the surface and protect it from dirt.

    b) Penetrating Care
    Penetrating care is achieved with leather oils and fats. These assure the leather maintain its supple soft touch and helps assure the water repellency.

    1. Care of Velour, Suede, Nubuk Leathers
    Here no fats or waxes are used, this closes or gums the surface.
    These leathers are cleaned by brushing or lightly sanding the surface with sandpaper or sanding fleece, cleaning it from dirt or stained areas. Impregnating Spray is recommended.

    2. Care of Nappa Leather (smooth surface)
    Depending on the need the surface should be cleaned with a gentle detergent. Soaking of the leather should be avoided. After drying at room temperature the leather should be creamed with a leather crème and polished with a clean rag.
    Is your special garment regardless of your care still not presentable, bring it to a cleaner who specializes in leather garments. Here it will be professionally cleaned, impregnated and through special touch up coloring brought back to life.
    Milled Leather
    Milled Leather is the Surface Structure of the Hide.
    The leather is during the production put into the milling machine where it is rotated, comparable to a large clothes dryer just with the absence of air and heat. Through the soft falling action the natural fine lines in the leather are intensified. The industry then speaks from "dinstinctive Milled Leather".
    Craquelé Style
    Craquelé is the artistic way of aging the leather surface.
    Stylistic devices: The wrinkling of leather is a way of artistically aging the leathers surface structure. This requires special devices to be administered whereby during the drying process special structures are achieved, this allows cracked surface areas to be simulated.
    Editor(s): Stefan Giese

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    Lederhaus Giese GmbH,   Sonnenwall 69,   47051 Duisburg,   Germany
    Tel. : +49 203 518860-0  |  E-Mail: info@Lederhaus.de  |  Internet: www.Leatherhouse.com