AIC's 52nd Annual Meeting

The preservation of art objects and valuable collections within historical buildings poses a unique challenge, primarily because these structures were not originally designed to protect such items sustainably. One notable example is the 15th-century Mehrangarh Fort Museum in Jodhpur, India, which houses an irreplaceable collection. This fort, stretching over 500 yards in length, ranks among India's largest forts. The museum houses an extensive and invaluable collection of silver artifacts, ranging from pure silver to electroplated variations, each representing various forms and types of silver objects. Recognizing the significance of preserving this remarkable collection, an educative program on conservation and preservation of silver artifacts was designed incorporating air quality risk assessment. The collaborative endeavour was part of the in-house training program hosted by the Mehrangarh Art Conservation Centre, Mehrangarh fort, Jodhpur in October 2022 under the Tata Trusts- Art Conservation Initiative Project. This assessment sought to quantify the concentrations of pollutants employing non-invasive, on-site pollutant sampling devices. The collected samples underwent laboratory analysis, utilizing Gas Chromatography for gaseous pollutants and Atomic Absorption Spectrometry to detect elements. The air monitoring survey had a specific emphasis on safeguarding the historic silver collection while assessing indoor microclimate, air pollution, and suspended particulate matter deposition.

Measurements were made in following locations inside the museum complex:

• Open courtyard
• Open Howdahkhana gallery displays finest example silver elephant seats from 17th-19th century in well-defined spaces with proper natural light and ventilation.
• Two closed showcases from the Daulat Khana Gallery. One of the cases displays Solid Silver Idol of Goddess Gauri (Case I) that is being worshipped by her Highness and another case displays seven decorative silver objects (Case II).
• Storage room for reserved silver collection

The analysis of air quality revealed unexpected and critical findings. Firstly, the outdoor environment displayed a minimal concentration of H2S, nearly at the detection limit, posing no immediate concerns. Secondly, monitoring in the open Howdah gallery indicated lower H2S levels due to natural ventilation. Thirdly, and the most striking findings was the alarmingly high levels of H2S in the closed showcases in Daulat Kahana Gallery. Surprisingly, despite the high H2S concentration in Case I, corrosion of silver was at its lowest. This was attributed to factors such as low humidity and pH levels due to its location, as well as textile barriers. Additionally, the formation of Cu2S suggested the presence of copper, possibly in jewellery or the idol itself, indicating a possible Ag-Cu alloy. In contrast, Case II showed higher corrosion levels, including sulfide and oxides of silver, indicating elevated humidity, alkalinity or the presence of strong oxidizing agents. Objects of both the cases underwent further analysis for their elemental composition using handheld XRF. Finally, in stark contrast, the storage room exhibited the worst conditions, marked by high concentrations of H2S, ozone, ammonia, and particulate matter (PM 2.5 and PM 10). The survey showed that adverse conditions arose from the incorporation of modern materials into the traditional structure, high RH, elevated alkalinity, pollutant accumulation etc.

In conclusion, the assessment of air quality within the Mehrangarh Fort Museum has revealed unexpected findings, particularly concerning the alarmingly high indoor levels of H2S and other pollutants, posing a significant risk to the precious silver artifacts. Furthermore, this study underscores the significance of collaborative projects and emphasizes the necessity of capacity-building training programs, highlighting the delicate balance required between scientific conservation efforts and the constantly evolving external environment.