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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 Ultra?violet 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 non?medical 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 broad?brimmed
hats, long pants and long?sleeved shirts to
reduce exposure.
Wear sunglasses that provide 100% UV ray
protection.
Always wear a broad?spectrum 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 broad?spectrum 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. About the Author For more information on Tanning please visit the Tanning resource center at http://www.safe-tanning-guide.info
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