Tanning : The process of making leather from skin
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