SOAKING DEFECTS

Soaking defects

short,inadequate duration of soaking

is a particular source of defect of dried and partly dried skin and hide results

in a hard tinny texture of the leather of hides and hides section which have have not been adequatly soaked.

this is due difference diffusion of the subsequent treatment chemical into the skin fibers which are still partly stuck together. A perfect soak is obtained by the addition of wetting agents and alkaline sharpners. Mechanical drumming or stretching on blunt fleshing machine also promote the soaking defects.

Low soaking temperature <15>

lower temperature of the liquor slows down and inhibits the
Soaking process. the water absorption of the skin is reduced .furthermore a certain

hardness and firmness of the skin is evident.

excessive soaking temperature >28 degree centegrate

soaking temperature exceeding 28 degrree cent. can lead to undesired high bacterial growth and furthermore to greater hydrolytic degradation of skin substance,substance resulting in a flat and tinny leather quality.Prevention is only possible by adding higher amount of disinfectants.

Damage caused by mechanical process

In particular when soaking dried hides or partly dried ,salted hides the grain may become cracky as a consequence of indequate preliminary soaking followed too quickly by the subseuent treatment,or due to an excessive rotational speed of the drums.

Roller in the mixture
Caused by overloading and inadequate soaking. When the drums are overloaded so that the skin can not move easily in drum float some inner portion remain dried which cause chemical penetration problem in subsequent process
Damage caused by microbial activity

1. Miner damage due to putrefaction
No visible on the soaked hide. Noticeable by putrid smell and matt, lusterless or blind sections in the grain of the leather.

2. Serious bacterial damage
Noticeable on the soaked hide by initial signs of hair-slippiness and /or slippery surface. Is revealed in the leather by loose grain and reduced firmeness.
Heavy putrefaction
Noticeable on the soaked hide by pitting, holes, putrefaction marks on the grain and also by complete loosening of the grain layer. Smell can also be observed and hair removal in soaking.
Remedy
All the above damage can be avoided by addition of bactericidal agents and by reduction of the soaking temperature.
Soaking defects of pickled pelts
Acid swelling
Irreversible damage of the fibers is caused by soaking with a common salt addition of less than 6º Be´.
Soaking defect of fish skin
Decomposition of skin substance
Increased protein decomposition is possible in many sorts. Therefore the soaking temperature should be below 20º C and only products with a neutral reaction should be used if an addition of wetting agents is necessary.