World Library  
Flag as Inappropriate
Email this Article

Liming (leather processing)

Article Id: WHEBN0010445610
Reproduction Date:

Title: Liming (leather processing)  
Author: World Heritage Encyclopedia
Language: English
Subject: Leather, Tanning, Leather production processes, Parchment, Aniline leather
Publisher: World Heritage Encyclopedia

Liming (leather processing)

In Liming for parchment or leather processing, the hides are soaked in an alkali solution by a drum/paddle or pit-based operation where five main objectives are met. The objectives are:[1]

Liming operations of cattle hides usually last 18 hours and are generally associated with the alkaline phase of beamhouse operations.

Removal of interfibrillary proteins

The interfibrillary proteins are denatured by the presence of alkali (particularly sodium sulfide), rendered soluble, facilitating their removal from the leather. Removal is done by the mechanical action of liming or reliming, but more prominently when the pelt is deswelled (during deliming). Failure to remove these proteins results in a hard, tinny leather (due to fibre glueing upon drying) that is brittle and inflexible.

Keratin removal

Keratin that is present in the hair, scales and in the epidermis of the skin is hydrolyzed in the presence of alkali (at pH values greater than 11.5). The disulfide bridges found in keratin protein are cleaved but can be reformed. Long periods of liming will result in hair removal. The main removal of keratin is performed using the unhairing operation. In traditional processing liming/unhairing was indivisible and took place at the same time. Modern liming methods, and in particular, the processing of sheepskins the hair is removed first and then limed in a liming drum. In hair-save technology, the hides are unhaired first and then limed for a further 12–18 hours.

Alkaline collagen swelling

The presence of calcium hydroxide results in the alkaline swelling of skin. The result is the influx of water into the hide/skin and a marked increase in fibre diameter and fibre shortening. The thickness of the skin increases, but the surface area of the pelt decreases. The weight increase, due to the uptake of water results in a doubling of the hide/skin weight. But this weight also needs to take into consideration that proteins (especially the hair) have been removed and the fleshing operation is often performed after liming.

Collagen fibre bundle splitting

The action of liming, in particular the swelling of the skin, results in the splitting of the fibre bundle sheath. Due to the fibre diameter increasing, the bundle sheath cannot contain the thicker fibres and it bursts open. This allows increased access to the fibres which allows better tanning, retanning, dyeing and fatliquoring.


  1. ^ Sharphouse, J.H. Leather Technician's Handbook. Leather Producer's Association. p. 104.  
  2. ^ An Introduction to the Principles of Leather Manufacture by S.S.Dutta p.160
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.