Washing and Rinsing in leather

Rinsing or washing processes and its environment effect
Rinsing and washing processes in leather production are absolutely necessary in almost all beam house operations. Where possible, the rinsing processes-which are mostly uncontrollable and require large amounts of water, should be replaced by the more economical washing baths.
Soaking
The preliminary soak, or first soaking bath, should always be removed because it contains a high accumulation of constituents such as salt, dirt, dung soluble protein albumin and globins and also preserving agents.
Harmful waste in bath
The washing bath contains dirt, dung (sometime blood) and albumin protein and biocide used in soaking process can give harmful effect on environment.
Liming
After depilation and opening up of the skin it is imperative that the lime liquor be drained and followed by a washing bath. Liming chemicals not used up, dissolved residues of keratin and hair, and fat saponification products must be removed. By doing this prewashing we removed excess of sodium sulphide and lime so that the subsequent process requires less chemical for deliming. The subsequent washing bath serves to make the slippery surface of the limed pelts easier to handle in the following mechanical treatment processes such as fleshing and splitting. Often an intermediate reliming process is performed at this stage, depending on the type of leather, or cream of lime is added to the washing bath in order to avoid lime blast through the action of air.
Harmful waste in bath
Sodium sulphide or Sulphydrate, lime used in liming process for hair or wool removing and skin fibers opening up can damage marine life.
Deliming & bating
The addition of deliming agents causes the formation of readily or slightly soluble calcium salt which have to removed from the process, as do the unused enzyme contained in the bate in order to avoid refermentation. A washing bath is essential.
Slippery touch further reduced in this washing.
Harmful waste in bath
Deliming agents such as organic acid, ammonium sulphate, ammonium chloride. Bating agents such as enzyme and acid bat.
Degreasing
After degreasing a washing bath is required so that all fatty matters which have been emulsified by means of surfactants and fat solvents are removed from the skin.
Harmful waste in bath
Degreasing agents such as organic solvent or emulsifiers and fat removed.
Wet back
After wet back process a washing is essential so that surfactant and wetting agents can be removed.
Harmful waste
Surfactant, emulsifier, ammonia & organic acid if used.
Neutralization
As in neutralization process salt and water are formed so the washing becomes necessary to do. This well washing removed the formed salt and also excess of acid and neutralizing agents.
Harmful waste in bath
Neutralizing agents such sodium bi carbonate and salt.