Abstract

Extensive studies have been carried out on combination tannages involving basic aluminium sulphate (aluminium sulphate, masked with citrate anion) and bagaruwa (Acacia nilotica var. adansonii). The use of aluminium as one of the tanning agents was found to impart improved physical properties. Amongst the combination systems evaluated, a bagaruwa pretannage followed by retannage with basic aluminium sulphate was found to produce stronger leathers. Nigerian tanneries can largely substitute chrome with the indigenously available aluminium tanning agent, the benefits being to reduce the import of chrome and to reduce the pollution due to chrome. Adoption of bagaruwa-aluminium combination tannages in other tanneries in the sub-region where only bagaruwa is available locally, will help to limit chrome pollution and may prove beneficial cost-wise. In addition to the above benefits achievable by mechanised tanneries, this technique will pave the way to upgrading the crust leathers produced by traditional tanners using only bagaruwa tannins.