Aim of the present proposal is to apply water-soluble alkali-silicates ("Wasserglass") in leather production. During the beamhouse processes (soaking, unhairing and opening-up of the fiber structure) in order to prepare hides and skins for the tannage, Wasserglass will be applied as pretanning agent hl order to stabilize the pelts (i.e. unhaired hides and skins) for shaving.
Shaving is a mechanical procedure in order to reduce and level the thickness of hides and skins, where shavings (thin, small pieces, or cuts, from the flesh side of leather) will occur. At State-of-the-Artprocesses, shaving is either carried out with pre-tanned hides and skins, or after the main-tannage. While shavings from pre-tanned pelts do not contain any chrome tannin (main tanning agent), and so can be disposed as sanitary landfill. shavings from tanned pelts ("wet blue") contain trivalent chrome.
For further utilization, these chrome-shavings have either become de-tanned (for protein production) or pressed with a binder in order to produce leather board. Since the demand for leather board is very limited and de-tannage requires many washing processes in order to remove the chrome completely, most of the chrome-shavings have to be disposed at special dumping sites.
With the application of Wasserglass, it is to expect that the fibers will not become tanned in the common sense, but sufficiently stabilized in order to withstand the mechanic strain of shaving. As this treatment will be carried out prior to any tannage, the arising shavings will only contain alkali silicates, which easily can be removed, and so a native hide fiber will be obtained. This material can be easy utilized for many purposes, e.g. as starting material for protein productiom As the stabilizing Wasserglas can also be removed easily from the shaved pelt, the following tannage can be carried out with every tannin, and also without changes hl technology.
If this procedure once will be implemented into leather industry, up to 50 000 tons of chrollleshavings can be avoided only in the European Union. Moreover, as Wasserglass is a cheap and common, non-poisonous auxiliary, neither an increase of production costs nor any environmental or work-place-risk are to expect. On the contrary, saving of disposal costs will make the procedure feasible for the European tanners.
Funding SchemeCRS - Cooperative research contracts
56029 S. Croce Sull'arno