Gresy Griyanitasari successfully defended her dissertation on a closed dissertation examination that was conducted on Monday, January 26nd 2026. In her dissertation, Gresy put a highlight on the low level of chromium absorbance on sheep leather. Gresy conducted this research by analyzing the impact of temperature, time, and the amount of chromium towards the shrinkage temperature of wet blue leather, the amount of Cr203 absorbed, and the total amount of chromium on liquid waste. The optimization process was done by using Response Surface Methodology (RSM) with Box-Behnken design. Other than that, this research is also evaluating the morphology of crust skin and the physical characteristic, colour evenness, and the morphology of finished skin surface with various coating types.
The result of this study showed that the optimal condition of tanning is reached at the temperature of 44,17℃ for 240.12 minutes by using as much as 7.00% chromium. The crust leather resulting from this process has a compact texture and is viable to be continued to the finishing step. On the final step, skin with Light Covering (LC) type coating shows the best physical characteristic, a good evenness of colour, and a surface of the skin that is smoother with a more closed pores compared to other types of coating.
This dissertation examination was led by Prof. Ir. Budi Guntoro, S.Pt., M.Sc., Ph.D., IPU., ASEAN Eng. as the chair of the examination. The promoter team consisted of Prof. Yuny Erwanto, S.Pt., MP., Ph.D., IPM., Prof. Ir. Ambar Pertiwiningrum, M.Si., Ph.D., IPU., ASEAN Eng., and Prof. Ir. Nanung Agus Fittriyanto, S.Pt. , M.Sc, Ph.D., IPM. The other examiner team consisted of Dr. Wagiman, S.TP., M.Sc,. Ir. Yuni Kusumastuti, S.T., M.Eng., D.Eng., IPM. and Dr. Ir. R. Lukas Martindro satrio Ari Wibowo, S.Pt., M.P., IPU., ASEAN Eng.
In this closed dissertation examination, Gresy was declared to pass with minor correction and is considered viable as a doctorate candidate. Through his research, Gresy was able to publish two international publications. Currently, Gresy is finishing her manuscript of her research to be published in a Q1 indexed journal.
Original article: Gresy Griyanitasari Teliti Optimasi Proses Penyamakan Utama Kulit Domba
Translated by: Widadullah Ragid Addiraya