Chemical, mechanical and manual processes that lead to the final product.
All chemical operations occur with the use of water in the drum, the typical tannery machine, constituted by a cylinder, which rotates around its own axis and which contains leathers, water and chemical reagents mixed individually by algorithms.
Subsequently (or together with the greening process) skins proceed to the mortar, that is the relaxation of the dermal tissue in order to increase the absorption capacity of tanning products (also by chemical processes). It is also useful to the peeling of the skin by partial saponification.
The lime is then removed with the purge. In this phase, water is added and the pH is lowered up to values close to those of the isoelectric point of collagen. The pickle completes the purge phase using acids (sulfuric and hydrochloric). The dermis deflates and gets a pH (2.8 to 3 degrees) suitable for the next stage of tanning.
The tanning step preserves the epidermis from organic degradation conferring mechanical resistance to temperature, moisture and chemicals agents. These characteristics are obtainable through the use of chromium which has an astringent effect on tanned leather and is solvable through the basification (increases the PH of about 4 degrees) so as to bring it back to the original thickness.
Alligator skins stay five days on special racks in order to permit chromium to fix correctly.
Just out from the drums, skins undergo the process of wet shaving in order to obtain a uniform thickness over the entire surface (about 1.1 / 1.5 cm). They pass through a series of rollers with sharp blades which remove part of the skin. Then they switch to synthetic tanning in order to be whitened
and allow coloring during the dyeing process. Drying takes place on the roundabout chain with an oven above and taking half a day with temperatures around 30 degrees.
Selection and dyeing
After drying, skins undergo the first division for selection and size directly from the roundabout chain.
This takes place in the crust warehouse. They are then stored and catalogued in order to be immediately available according to customer orders. Before dyeing them, a color master is given both to the technicians and to the client. In this way, it is possible to obtain the finished product without wasting material. The recipe of the background color obtained is then replicated in the production phase using small drums for about 3-4 hours, in which tanned skins are placed in perforated bales so as to avoid kinking. In this stage technicians proceed with the skins fattening, established in mutual agreement with the customer through the master.
The drying of products derived from alligators, ostriches, lizards and alligator’s hips takes about half a day and is done in a oven (temperature around 35°). In order to avoid folds clamps, which hold hanging skins, are used. For snakes, lizards etc. the drying is done by stretching skins on slightly heated steel plates, or on glasses, or even in a natural way, in relation to the size of the skin.
The finishing process
The finishing process is aimed at improving the leather’s appearance, in addition to protecting the surface. It includes several mechanical and chemical operations that affect the skin’s appearance, for example the softness (with waxes and oils), the gloss (with resins and caseins) or further staining (supra color or removable), so as to obtain the desired color and other characteristics.
The finishing process includes:
- “volanatura”: rotation of the leather so as to break up its rigid surface and give softness to the article
- dry shaving: to achieve the thickness of the master
- finishing by spray machine: an automated process on the roundabout chain for production of standard articles, or manual process done under an aspiration cab for samples or special items
- rolling finish: skins go under rollers or brushes in order to soften them and give opaque or semi-shiny reflections.
- polishing: through the rubbing of an Agata stone constant heat is generated (80 ° C at maximum pressure). The skin becomes stiff due to the hardening of the previously applied casein and appears full of mirrored reflections.
- manual work:
- hand buffing to get deeper colors or to penetrate the scales;
- discoloration which, by a further wash through an automatic spray, gives the skin a vintage effect
- painting, with which it is possible to get extremely customized products.