Retanning Resin rev.2 from 13/05/13


Aspect Viscous Liquid
Colour Dark brown
Odour Characteristic
pH (sol. 10%) 5.5 ± 0.5/
Active Material 38 % ± 1.0
Solubility Soluble in water
Ionic Charge Anionic


ALFASIN B is a retanning product resulting in the association of an acrylic polymer and polyphenolic moieties.
Both entities, linked through a chemical reaction, associate to form a resin which is both vegetable and polymeric.
As indicated in the second part of this leaflet, this particular disposition confers to the product special properties.


The first consideration to be mentioned is that the resin through his vegetable part integrates poly phenolic moieties which have the possibility to react and establish links with NH moieties of the proteinic chain inside the skin producing a tannig effect.

Due to the great number of reacting moieties, ALFASIN B has a strong capacity to fix on the leather: Hide powder analysis shows a tanin content greater than 80 % mesured on dry material.

As a consequence ALFASIN B may act as a non rigid cross linking chain as well as traditional filling resinic macromolecule, both action modes confering it properties similar to a non resinic filler (such as proteinic fillers).

Since free phenolic residues are available, ALFASIN B may react with other products used during the retanning process, allowing a better fixation and consequently a better use. Dyestuff as well as fatliquors and eventually other products used in the process seem to be better fixed inside the leather, since comparative COD measurement in residual bath show lower values when ALFASIN B is used.


ALFASIN B finds its better use in chrome leather retanning.

The quantity to apply naturally depends on the type of item to be produced and specifically on the properties to be imparted to the leather. Nevertheless the originality of ALFASIN B consists in the fact that it can be applied in a percentage varying from 3 to 20 % calculated on the shave weight Taking in account the strong affinity of ALFASIN B with the leather, the best stage to insert it comes after a complete and uniform neutralisation.
The pH of the leather results being a determinant factor for the complete prenetration of the product inside the skin.
Too acidic pH tends to quickly fix the product; on the contrary, pH value around 5,0 - 5,4 diminishes affinity and thus accelerates his diffusion inside the dermic structure.
ALFASIN B is compatible with all types of anionic products and may be added to them either before or after introduction of synthetic or vegetable tannins. A good way to proceed consists in initiating the retannage pouring first the ALFASIN B and then add the other components after 20 minutes.
As well known for other products, such as vegetable tannins, an increase in temperature tends to increase the global fixation of the product. As a consequence it is indicated to initiate the addition of the ALFASIN B in a rather short and cold bath, increasing the temperature during the fatliquoring phase by addition of hot water or any other mean.


Chemical-physical properties of the product have been determined in accordance with internal procedures by methods of analysis provided by national and / or internationally recognized standards. The information contained in this data sheet is based on our current knowledge. Given the multiplicity of factors that can influence the processing and use of our products, it is the responsibility of the customer to carry out its part tests and controls.
We cannot endorse any responsibility consequent to an incorrect use of the product.