Tanning : The Process Of Making Leather From Skin

By Michael Sanford

Tanning: The chemical and mechanical process used to treat hides and eliminate perishability. Tanning is the process of making leather from skin. This is commonly done with the acidic compound tannin, which prevents normal decomposition and often imparts color

There are two types of skin tanning. Immediate tanning is a response to the UVA radiation of sunlight. This tanning arises just a short time after sunbathing and lasts only a few hours or days. Delayed tanning is caused by the UVB radiation of sunlight. It appears approx. 2-3 days after sunbathing and lasts longer, disappearing with natural renewal of the skin. The intensity of tanning depends on the skin type.

The process of dressing up animal skin/hide into leather consists of three stages. The first stage is the preparation for tanning. The second stage is the actual tanning and other chemical treatment. The third stage applies finishing to the surface.

In preparation for tanning, the skins (of smaller animals like goat, sheep, lamb, pig, etc) or hides (of larger animals like cow, buffalo, etc) are washed, treated with lime/sulfide to remove hair and natural fat, then delimed to remove sulfide and acidified to prepare for tanning.

The majority of leather produced today is tanned using chromeIII tanning material. In the raw state chrome tanned skins are blue and therefore referred to as “wet blue”. The wet blue is then split for the desired end product, garment upholstery, shoe upper etc, followed by dyeing (to give color), fat liquoring (to add fat/oil) and retanning (to fill up the fiber structure) in wet condition.


The leathers are dried and mechanically softened and prepared for finishing. Finishing is usually done by coating the surface with paint-like mixes. Suedes, Nubucks, etc. are finished by raising the nap of the leather by rubbing with emery paper (sandpaper).

Another process, that was used by Native Americans, involves “tanning” the skin using brains. First, the hide can be strung in a frame. Second, the flesh from skins is scraped as before. Then the hide is allowed to dry after which the hair on these skins is shaved off. Then, brains are mixed with a minimum of water. The hide soaks for 24 hours. Then, you stretch it as it dries. Finally, you sew the skin in a bag and smoke it using rotten wood placed on coals.

Public health experts and medical professionals are continuing to warn people about the dangers of ultraviolet (UV) radiation from the sun, tanning beds, and sun lamps. Two types of ultraviolet radiation are Ultraviolet A (UVA) and Ultraviolet B (UVB). UVB has long been associated with sunburn while UVA has been recognized as a deeper penetrating radiation.

Although it’s been known for some time that too much UV radiation can be harmful, new information may now make these warnings even more important. Some scientists have suggested recently that there may be an association between UVA radiation and malignant melanoma, the most serious type of skin cancer.

What are the dangers of tanning?

UV radiation from the sun, tanning beds, or from sun lamps may cause skin cancer. While skin cancer has been associated with sunburn, moderate tanning may also produce the same effect. UV radiation can also have a damaging effect on the immune system and cause premature aging of the skin, giving it a wrinkled, leathery appearance.

The American Medical Association (AMA) and the AAD have warned people for many years about the dangers of tanning. In fact, AMA and AAD have urged action that would ban the sale and use of tanning equipment for nonmedical purposes. Doctors and public health officials have recommended the following steps to minimize the sun’s damage to the skin and eyes:

* Plan your outdoor activities to avoid the sun’s strongest rays. As a general rule, avoid the sun between 10 a.m. and 4 p.m.

* Wear protective covering such as broadbrimmed hats, long pants and longsleeved shirts to reduce exposure.

* Wear sunglasses that provide 100% UV ray protection.

* Always wear a broadspectrum sunscreen with Sun Protection Factor (SPF) 15 or more, which will block both UVA and UVB when outdoors and reapply it according to manufacturer’s directions.

* Seek immediate medical attention if you receive skin or eye damage from the sun or if you experience an allergic reaction to the sun.

* See your dermatologist or personal physician if you develop an unusual mole, a scaly patch or a sore that doesn’t heal.

* Always wear a broadspectrum sunscreen with Sun Protection Factor (SPF) 15 or more, which will block both UVA and UVB when outdoors and reapply it according to manufacturer’s directions.

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