Abstract

This study is aimed at combining the usage of valonia and modified valonia extracts with oxazolidine to obtain an increase in hydrothermal stability, and thus to develop tanning efficiency and to produce leathers that have better properties then the ones tanned with valonia extract only. Natural and three modified valonia extracts and oxazolidine were used as tanning materials. Skin samples were divided into two groups. In group A, valonia extracts were used as tanning materials and oxazolidine as retanning agent. Group A was divided into 4 subgroups according to the used extract type. Each subgroup was also separated into four lots according to the oxazolidine percentages used. Group B; where oxazolidine was used as pretanning while valonia extracts as tanning agents, was divided into three subgroups according of oxazolidine usage. Each subgroup had four lots according to the used extracts. General means of Shrinkage Temperatures (Ts) for natural extract, group A and B were found as 65.66, 78.62 and 83.42^oC, respectively, indicating that the oxazolidine pretanning followed by valonia retanning provides better tanning efficiency. On the base of the unique experiment, 4% oxazolidine and 20% least modified vegetable tannin combination gave the best result.

Key words: Leather, tanning, tannin, valonia, oxazolidine, vegetable, shrinkage temperature.