From vegetable tanning to wet blue and wet white tanning
Tanning refers to the procedure of chemically treating raw hides to make it stronger, more flexible and resistant to decay.
The tanning process consists in strengthening the protein structure of the putrescible skin by creating a bond between tannins and peptide chains. The skin is made up of three layers being the epidermis, dermis and subcutaneous layers. The dermis consists between 30-35% protein, mostly collagen, and the remaining are fat and water. It is the dermis that is used to make the leather after the other layers have been removed chemically or mechanically. During the tanning process, acids, alkalis, salts, enzymes and tanning agents are used to dissolve the fats and non-fibrous proteins, as well as chemically bond the collagen fibres with the tanning agents.
Thanks to its 160 years of history in vegetable extracts and its expertise in providing solutions on wet white tanning at low environmental impact, Silvateam R&D laboratories have recently developed innovative technologies for sustainable leather making, called Ecotan.
Ecotan tanning systems
Traditional vegetable tanning (chrome-free)
It is the most traditional and oldest way of tanning hides. Most of the process is done in a traditional way, especially in Italy, where expert craftsmen combine their knowledge and history with high quality raw hides and innovative modern technologies. Vegetable tanning uses natural ingredients, tannins / polyphenols extracted from the bark, wood, fruit and leaves of trees. This means the finished product colour is usually warm, rich tones of natural browns.
Wet white tanning (chrome-free)
This refers to leather with a pale cream or white colour. This fairly new method of tanning has been gaining popularity, partially due to increased concern for the environment. Wet white tanned leathers are free of chrome and recyclable. The main products used for wet white tanning are synthetic tannins, such as phenolic, disulphonic and naphthalenic products, aldehydes, metals (Zirconium, Aluminium, etc.) and oils.
Hybrid chrome tanning
The latest solution at Silvateam consists of an innovative hybrid tannage using a combination of chrome salts and Blancotan CAT, a new syntan based on a dihydroxydiphenyl - sulphone condensation product.