Tanning

 Tanning - the stage of the leather industry, which consists in the processing of raw leather tanning agents for resistance to decay while maintaining the strength and softness. It can be performed using vegetable substances (red tanning), metal salts (mineral) and fat (zamshevanie). Vegetable tannins - a pulverized spruce, willow and oak bark. A mixture of bark pour skins in special pits or tanks and fill with water. The main rule of this stage - a gradual increase in the concentration of tanning solution. This is a long process that requires moving the skins from one well to another. End of tanning is determined by external characteristics. When mineral tannage using various chromium compounds, the process may take place in one or two stages with the movement of skin from one solution to another.