Wet end processing of Zeology tanned leather

How to produce crust leather from Zeo White?

Zeology tanned leather is different compared to chrome and glutardialdehyde (GDA) tanned leather. When processing Zeology tanned leather (Zeo White), it is important to recognize that differences exist between leathers made with Zeology and other tanning agents.  


Differences between Zeo White and wet white & wet blue for wet end processing: 

  • Both chrome and GDA bonds are local and strong. While Zeology’s individual bonds are weaker and remain susceptible to protonation, the sum of the combined bonds form strong interactions with the collagen. 
  • Zeology tanned leather therefore neither behaves as typical chrome, it lacks the cationic charge, nor as a typical GDA leather because its amino groups remain receptive.
  • Zeo White possesses a relatively compact, intrinsically tight grain. The emphasis of retanning therefore shifts to creating fullness and softness. 
  • Zeo White is a dynamic material. In retanning the initial portions should be made of low-astringency products. These can be followed by products of higher astringency. 
  • Zeo White has an off-white intrinsic color. 
  • As in the case of tanning with chrome tannage, Zeology is classified as a mineral tannage but the product is not a metal tanning agent. Whereas chrome tanned leather possesses an Iso Electric Point (IEP) of approximately pH 6.6, that of Zeo White lies between pH 3.8 and 4.2. Even though Zeo White’s IEP is close to that of GDA tanned wet white, it behaves differently than the latter. 
  • While chrome tanning agents react with carboxylic acid and GDA with amino groups only, Zeology interacts with both.  

Technical paper

Upon request a technical paper is available that describes the wet end processes in detail for Zeology tanned leather. 

For more detailled information or to receive the technical paper please reach out to Pim.

Pim Wilgenburg Business Director Nera