Understanding Chemistry of Black Coating in Ancient Bidriware and Attempt to Obtain Similar Coats on Pure Copper and Yellow Brass

Abstract:

Bidriware is an ancient metal-based object of Art from South India dating back to 14th Century A.D. The base casting in a Bidriware work is made of a Zn-Cu alloy in the ratio of 16:1 while the inlay work is hemmed with pure silver. The black patination obtained on the surface of Bidriware has been a source of mystery and intrigue for a long time. In this work, this black patination has been investigated to understand the chemistry behind it. The patination in Bidriware is actually a combination of Cupric oxide, Cupric chloride and other minute quantities of cuprous oxide, cupric nitrate and Zinc oxide, which are the results obtained from XRD, SEM, Optical microscopy and XRF analysis. We have further found that similar black patination can be obtained on the surfaces of pure copper and yellow brass. Since black oxide layers have multiple applications in many fields for the property of black body, a novel method, based on ancient knowledge, has been suggested here to obtain similar surfaces on pure copper and yellow brass samples.

• Periodical: Materials Science Forum (Volume 1087)
• Pages: 127-133
• DOI: https://doi.org/10.4028/p-akq88z
• Online since: May 2023
• Authors: J.J.S. Pravallika, K.R. Phaneesh*, Bandla Subbarao, Akula Bhuvaneshwari
• Keywords: BIDRIWARE, Optical Microscopy, Pure Copper, SEM, XRD, XRF, Yellow Brass, Zn-Cu Alloy

References

[1] The technical examination of bidri ware, Susan La Niece & Graham Martin (1987) The technical examination of bidri ware, Studies in Conservation, 32:3, 97-101.

DOI: 10.1179/sic.1987.32.3.97

[2] Alternative Method of Processing Bidri-Ware Crafts: An Electrochemical Study, A Thesis Submitted By Akshaykumar Varma

[3] Bidri Ware: A Unique Metal Craft of India, Dr. Anjali Pandey, "Bidri Ware: A Unique Metal Craft Of India" International Journal Of Research – Granthaalayah, Vol. 4, No. 3 (2016): 170-175.

DOI: 10.29121/granthaalayah.v4.i3.2016.2799

[4] In Vitro Degradation of Absorbable Zinc Alloys in Artificial Urine Sébastien Champagne, Ehsan Mostaed, Fariba Safizadeh, Edward Ghali, Maurizio Vedani and Hendra Hermawan.

DOI: 10.3390/ma12020295

[5] Scientific and Technical Study of Bidriware Dr. Nalini Avinash Waghmare.