Mineral- Vegetable Combination Tannages and Retannages Based on Acacia nilotica (Sunt) Bark Powder

Abstract

The aim of this study is the application of garad barks (Acacia nilotica) as local tanning material for the production of upper leather. Garadbark which was located at City of El Geneina (West Darfur State) and El Jaili (Khartoum State), was analyzed for tannins, non-tannins, total soluble, Total solid and %Moisture. Phytochemical investigations of garad bark widely distributed in Sudan have been carried out. Analysis of Garad bark gave the following values: tannin 23%, non-tannins 14%, total soluble 37%, total solid 41.45%, insoluble 54.35,moisture 8.65%, pH 5.5. The combination of vegetable tannins with metal salts has been used for thousands of years. In the present study, a combination tanning system based on garad bark has been studied. It was seen that the combination tanning using garad bark 20% with aluminum (2% Al2O3), (9% ZnO) resulted in leathers with shrinkage temperature more than the control (garad bark tanned) leather. The physical and chemical characteristics of experimental leather are comparable to control leathers. The experimental leathers are softer than the control leathers. Combination tanning system using20% garad bark - 2%Al2O3 is found to be better compared with other combination tanning systems.

Garad bark as alternative retanning agent for mimosa using wet blue has been studied. Most organoleptic properties of the experimental leathers produced from garad bark extract are better than control produced from wattle. However, softness property is better in the case of wattle retanned leather and the physical strength properties are comparable with matched pair control leather. Therefore using garad bark appears to be a good alternative for the retanning processes. Besides being technically feasible, retanninggarad bark is also economically viable as the cost of the garad bark extract is cheaper.