Abstract

The physical and chemical stability of low-chrome wet-blue stock was investigated at various storage pH values, temperatures and times. Chrome contents were varied between 20% and 80%, of normal tannage to determine minimum levels required to protect the hide structure from bacterial and hydrolytic damage. Behaviour of the leathers under storage was assessed from physical tests on the leathers in the wet condition as well as after fatliquoring and drying and from analysis of the interstitial liquor for free chrome and nitrogen. A feature of the results was the comparative stability of the tanned stock under storage at all levels of chrome content. Shifts in physical properties with chrome content were normal trends, while increases observed in grain extension at crack, slit tear and lastometer loads after storage represented beneficial changes. The low levels of soluble nitrogen and chrome in the leather liquors throughout storage indicated that degradation of the hide structure or breakdown of the chrome complexes in the hide was minimal. The experimental results demonstrate the feasibility of extended storage of wet-blue at extremely low levels of chrome application.