Wild shrub rich in sweetened tannins
The gambier (Uncaria gambir) is a wild shrub which grows mainly in China, India, Malaysia and Indonesia. In some areas of Asia, between the North and South 10th parallels, it is also cultivated with the pepper plantations. To prepare the extract, gambier’s leaves and twigs are boiled in water. The solution is then evaporated until a syrup is obtained and then cooled under agitation to promote crystallisation. The resulting solid is cut into 25mm cubes.
In order to overcome the dissolution problem and to make them suitable for tanning and re-tanning leather, the gambier cubes are dissolved with tannin dispersants. Gambier extracts commercialised by Silvateam are presented in the following categories:
- Gambier CM (crushed cubes) in the form of brown powder
- Gambier Purified Liquid (melted and purified cubes) in a viscous and dark brown liquid form
Gambier extract obtained contains mainly catechins and other compounds in smaller percentages such as sugars, salts, waxes, oils and minerals.
The extracts are used alone to confer rather soft leathers, with a fine touch and a reddish brown colour. These extracts are recommended for chrome re-tanning of cow hides and calf skins. They are also used as a dispersants in dyes and have shown good results in chrome tanned leathers suitable for gloves because they give fullness without altering the characteristics of softness and elasticity. A peculiar property of gambier extracts is to give the skin good glazed and glossy properties of the dyes. For the production of burnished or brushed articles, we recommend the use gambier in the final recipe in combination with formic acid.