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Electronic Appendix

Ochers in Rajasthan
Giovanni Cavallo, Dept. Environment Constructions and Design, SUPSI

Earth pigments have been widely used from ancient times to date.
India has an important historical background on the use of ochers and clay pigments in the arts. The main earth pigments deposits have been systematically studied in Rajasthan.

A precise and systematic knowledge of the materials used in the ancient and modern artistic objects represents the first step before projecting any conservation work. Earth sciences provide several analytical techniques for a better understanding of the origin, composition and even provenance of the raw materials used as pigments and for determining physical and chemical properties as durability, stability, compatibility; all these properties depend on the purity of the raw material.
Rajasthan State in NW of India is one of the most important locales in the production and export of ochers and clay pigments; occurrences of ochers are found at various places.
The project, developed in cooperation with Dr. M. K. Pandit, Head of the Department of Geology, University of Rajasthan, intends to characterize the raw materials occurring in a few districts of Rajasthan State (Bhilwara, Chittaurgarh, Udaipur) from a mineralogical and chemical point of view. This would provide a well-needed fill up in the knowledge and will be used in identifying and selecting appropriate type for restoration works in terms of stability and compatibility. In addition, the study would also open new fields for Indian researchers, being the application of geological sciences to cultural heritage conservation a new opportunity.

Geology, mineralogy and geochemistry of ochers (mineral pigments) in Rajasthan State (India)
The Indian partner is a geochemist and petrologist with more than 25 years of research and teaching experience. He is the leader of his research group in the university and has been successful in formulating and completing externally funded research projects.

The collaborative research project, discussions and field work with the Swiss partner and access to the laboratory allowed to enhance the knowledge of the Indian partner who also got an update on the latest developments in the relevant field treated in this project. Some students from the Indian partner university were directly involved and benefited through this exposure at the international level. The knowledge so gained will be disseminating among other students also who would be indirect beneficiaries of this collaborative research work.

The cooperation between Swiss and Indian University represented an important opportunity in terms of exchange of ideas, experiences and augmenting knowledge. The common background (geological studies) associated to specific knowledge in the field of geochemistry enriched and enhanced the Swiss competencies in the field of pigment study.

Results
The painting raw materials studied in the districts of Bhilwara, Chittourgarh and Udaipur (Rajasthan) show a strong connection between the host rocks and the deposits; the microstructure and the texture of the original rock are sometimes very well preserved. In many cases the reconstruction of the entire profile could be possible and the deposits can be described as an in-situ alteration profile.
The common character in the Bhilwara and Chittaurgarh districts is the association between white clays and yellow ochres (fig. 1); this is controlled by the geology where feldspar alteration is responsible for kaolinite formation sometimes in association with illite, and biotite alteration for yellow ochers (goethite).
Distinctive characteristics are the association kaolinite and kaolinite/illite with goethite and hematite. This is very useful for establishing the provenance of the raw materials, also in connection with the trace element analysis.
Other distinctive characteristic is the crystal quality. Some samples containing kaolinite show the (001) reflection at 7.16 Å broad due to their low crystallinity.
The high content of ilmenite is associated with basic magmatic rocks, mother rocks of clay-rich hematite.

All the paintings raw materials collected need a preliminary treatment before their use in order to separate the colouring fraction from the other minerals, generally quartz and calcite.

Regarding the analytical techniques adopted, petrography revealed many interesting aspects otherwise non detectable using ancillary techniques as XRD (X-ray Diffraction) and XRF (X-ray Fluorescence). The use of FTIR (Fourier Transformed Infrared Spectroscopy) was very useful for the fast analysis of clay minerals such us kaolinite and illite. Kaolinite-rich goethite samples didn’t show the goethite diagnostic bands because masked by the kaolinite absorption bands.

Applications
The studied areas show a large availability of earthy pigments (white, yellow and red) generally of good quality usable as source for natural pigments. These materials should be used for the conservation and restoration of architectural surfaces instead of synthetic pigments for a lot of reasons: the compatibility with the support and the other pigments, the stability in terms of time-resisting and in relationship to the climatic conditions, the respect with the traditional art of painting.
In many cases the use of modern pigments leads to a complete transformation of the original surface becoming flat, cold and extraneous to the environment (fig. 2).
As comparison it is possible to understand this difference looking at the colour used in villages where traditional materials have been used and not.

The long-term cooperation between SUPSI and the University of Rajasthan is intended to be oriented on the application of the results gained by the project.
The application will be oriented to the Shekhawati region (NW Rajasthan) famous for the paintings decorating the external and interior walls of the havelis.
Here original painting raw materials (yellow and red ochers, white clay, lime, green earth) some of them maybe coming from Bikaner district, have been used during the 18th century according to the traditional use. Nowadays the use of synthetic materials is transforming the original characteristics of this region visited by people coming from all over the world.

Key messages

Painting raw materials are expression of Indian art tradition
The collaboration between the involved institutions was very fruitful
The partner institutions are planning future collaborations developing projects on fields of common interest

The Partner Institutions

University of Applied Sciences Southern Switzerland
Dept. Environment Constructions and Design
Laboratory of Technical and Experimental Studies
PO Box 12 - 6952 Canobbio (Tessin, Switzerland)
www.supsi.ch

University of Rajasthan
Dept. of Geology
302004 Jaipur (India)
http://www.uniraj.ernet.in/Departments/Geology/bottom.html

Dr. M. K. Pandit, Head of the Department of Geology, University of Rajasthan
pandit-mk@uniraj.ernet.in
manoj.pandit@gmail.com

Project manager: Dr. Giovanni Cavallo
www.imc.supsi.ch; giovanni.cavallo@supsi.ch

Figure 1. Characteristic association between white clay and yellow ocher (goethite). Chittourgarh district, Rajasthan (India).

Figure 2. Use of synthetic pigments on the external walls of a havelis in Fathepur, Rajasthan (India).


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		Electronic Appendix Ochers in Rajasthan Giovanni Cavallo, Dept. Environment Constructions and Design, SUPSI Earth pigments have been widely used from ancient times to date. India has an important historical background on the use of ochers and clay pigments in the arts. The main earth pigments deposits have been systematically studied in Rajasthan. A precise and systematic knowledge of the materials used in the ancient and modern artistic objects represents the first step before projecting any conservation work. Earth sciences provide several analytical techniques for a better understanding of the origin, composition and even provenance of the raw materials used as pigments and for determining physical and chemical properties as durability, stability, compatibility; all these properties depend on the purity of the raw material. Rajasthan State in NW of India is one of the most important locales in the production and export of ochers and clay pigments; occurrences of ochers are found at various places. The project, developed in cooperation with Dr. M. K. Pandit, Head of the Department of Geology, University of Rajasthan, intends to characterize the raw materials occurring in a few districts of Rajasthan State (Bhilwara, Chittaurgarh, Udaipur) from a mineralogical and chemical point of view. This would provide a well-needed fill up in the knowledge and will be used in identifying and selecting appropriate type for restoration works in terms of stability and compatibility. In addition, the study would also open new fields for Indian researchers, being the application of geological sciences to cultural heritage conservation a new opportunity. Geology, mineralogy and geochemistry of ochers (mineral pigments) in Rajasthan State (India) The Indian partner is a geochemist and petrologist with more than 25 years of research and teaching experience. He is the leader of his research group in the university and has been successful in formulating and completing externally funded research projects. The collaborative research project, discussions and field work with the Swiss partner and access to the laboratory allowed to enhance the knowledge of the Indian partner who also got an update on the latest developments in the relevant field treated in this project. Some students from the Indian partner university were directly involved and benefited through this exposure at the international level. The knowledge so gained will be disseminating among other students also who would be indirect beneficiaries of this collaborative research work. The cooperation between Swiss and Indian University represented an important opportunity in terms of exchange of ideas, experiences and augmenting knowledge. The common background (geological studies) associated to specific knowledge in the field of geochemistry enriched and enhanced the Swiss competencies in the field of pigment study. Results The painting raw materials studied in the districts of Bhilwara, Chittourgarh and Udaipur (Rajasthan) show a strong connection between the host rocks and the deposits; the microstructure and the texture of the original rock are sometimes very well preserved. In many cases the reconstruction of the entire profile could be possible and the deposits can be described as an in-situ alteration profile. The common character in the Bhilwara and Chittaurgarh districts is the association between white clays and yellow ochres (fig. 1); this is controlled by the geology where feldspar alteration is responsible for kaolinite formation sometimes in association with illite, and biotite alteration for yellow ochers (goethite). Distinctive characteristics are the association kaolinite and kaolinite/illite with goethite and hematite. This is very useful for establishing the provenance of the raw materials, also in connection with the trace element analysis. Other distinctive characteristic is the crystal quality. Some samples containing kaolinite show the (001) reflection at 7.16 Å broad due to their low crystallinity. The high content of ilmenite is associated with basic magmatic rocks, mother rocks of clay-rich hematite. All the paintings raw materials collected need a preliminary treatment before their use in order to separate the colouring fraction from the other minerals, generally quartz and calcite. Regarding the analytical techniques adopted, petrography revealed many interesting aspects otherwise non detectable using ancillary techniques as XRD (X-ray Diffraction) and XRF (X-ray Fluorescence). The use of FTIR (Fourier Transformed Infrared Spectroscopy) was very useful for the fast analysis of clay minerals such us kaolinite and illite. Kaolinite-rich goethite samples didn’t show the goethite diagnostic bands because masked by the kaolinite absorption bands. Applications The studied areas show a large availability of earthy pigments (white, yellow and red) generally of good quality usable as source for natural pigments. These materials should be used for the conservation and restoration of architectural surfaces instead of synthetic pigments for a lot of reasons: the compatibility with the support and the other pigments, the stability in terms of time-resisting and in relationship to the climatic conditions, the respect with the traditional art of painting. In many cases the use of modern pigments leads to a complete transformation of the original surface becoming flat, cold and extraneous to the environment (fig. 2). As comparison it is possible to understand this difference looking at the colour used in villages where traditional materials have been used and not. The long-term cooperation between SUPSI and the University of Rajasthan is intended to be oriented on the application of the results gained by the project. The application will be oriented to the Shekhawati region (NW Rajasthan) famous for the paintings decorating the external and interior walls of the havelis. Here original painting raw materials (yellow and red ochers, white clay, lime, green earth) some of them maybe coming from Bikaner district, have been used during the 18th century according to the traditional use. Nowadays the use of synthetic materials is transforming the original characteristics of this region visited by people coming from all over the world. Key messages Painting raw materials are expression of Indian art tradition The collaboration between the involved institutions was very fruitful The partner institutions are planning future collaborations developing projects on fields of common interest The Partner Institutions University of Applied Sciences Southern Switzerland Dept. Environment Constructions and Design Laboratory of Technical and Experimental Studies PO Box 12 - 6952 Canobbio (Tessin, Switzerland) www.supsi.ch University of Rajasthan Dept. of Geology 302004 Jaipur (India) http://www.uniraj.ernet.in/Departments/Geology/bottom.html Dr. M. K. Pandit, Head of the Department of Geology, University of Rajasthan pandit-mk@uniraj.ernet.in manoj.pandit@gmail.com Project manager: Dr. Giovanni Cavallo www.imc.supsi.ch; giovanni.cavallo@supsi.ch Figure 1. Characteristic association between white clay and yellow ocher (goethite). Chittourgarh district, Rajasthan (India). Figure 2. Use of synthetic pigments on the external walls of a havelis in Fathepur, Rajasthan (India).