Leather vegetable-tanned

Finished ready-for-use leather, vegetable tanned leather and crust may have a different water content depending on the environment. A water content below 12 15% inhibits the proliferation of micro-organisms. However, sporogenic species may have released spores which withstand unfavourable conditions, e.g. great heat and dryness, but will germinate to a metabolic active state again as soon as favourable conditions appear. 

The apphcation of vegetable tanning materials has an additive effect on the leather. The more vegetable tannins appHed the more the leather becomes like vegetable-tanned leather. The color is changed, the fullness of feel increases, and the leather can be worked and embossed like vegetable leather. 

The si2e of the vegetable tanning molecules and the coUoidal nature of the system result in the fixation in the hide of filling materials. The filling action is essentially an impregnation of the hide to form a dense firm leather. These properties are gready desired in sole and mechanical leathers. 

The chrome tanning is one step in a compHcated series of leather operations leading from the raw hide to the finished products. Chrome tanning is the most important tannage for all hides except heavy catde hides, which are usually vegetable tanned. In heavy shoe uppers and soles, a chrome tanned leather is frequently given a vegetable retan to produce chrome retan leather. 

Cationic dyes were the first synthetic organic dyes employed for dyeing leather, initially for dyeing of vegetable-tanned leather. Currently, brilliant cationic dyes are used for enhancing the brilliance of the shades obtained with 1 2 metal-complex dyes. 

Bindings covered with vegetable-tanned leather are washed with pure toilet soap, saddle soap, or mild, high quality surgical toilet soap and a 7-10% solution of potassium lactate. 0.25% of p-nitrophenol can be added as a fungicide, but this is not necessary if the temperature and relative humidity are constantly satisfactory (see p. 5). The lactate, when applied to new vegetable-tanned leather, is thought to protect the leather from the deleterious action of sulfuric acid which usually forms in leather when sulfur dioxide is absorbed. It is. probable that it has little efficacy once chemical deterioration has started, and for some years doubt has been cast on its effectiveness, even on new leather, despite favorable results in laboratory tests. However, it is used, and its use is advocated just in case it is beneficial. 

Vellum. There is a great deal to be said for this material which has proved durability and is certain to last much longer than any present-day vegetable-tanned leather. Difficulties can arise with full-vellum bindings... 

A. Cassano, J. Adzet, R. Mofinari, M. G. Buonomenna, J. Roig, and E. Drioli, Membrane treatment by nanofiltration of exhausted vegetable tanning liquors from the leather industry. Water Research 37, 2426-2434 (2003). 

Use Vegetable tanning, retanning of chrome-tanned upper leathers, dyeing, ore flotation, oil-well drilling fluids, flavoring. 

Use Source of wattle bark extract, used in vegetable tanning of leather, especially retannage of upper leathers and production of heavy leathers. 

Materials used for leather dyeing are usually acid dyes, direct dyes, mordant dyes (Thorstensen, 1993) and reactive dyes (Shao and Zhao, 1984). Basic dyes are primarily used for dyeing vegetable tanned leather (Sandoz, 1949). 

Oil-tanned chamois leather Alum-tawed skins Formaldehyde-tanned leather Aluminium-tanned skins Vegetable-tanned leather (hydrolysable) Vegetable-tanned leather (condensed) Chrome-tanned leather... 

It has been suggested that vegetable tanning developed from a desire to colour oil or alum-processed skins. Interestingly the earliest surviving recipes for the preparation of leather, dating from Babylonian times about 3000 years ago, show that a combination of these three processes were employed ... 

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