Spectral Reference Database for the Analysis and Identification of Indian Pigments

A collection of 41 Indian pigments from the workshop of traditional miniature painter, Mr. Babulal Marotia, were characterized using transmission Fourier-transform infrared (FTIR) spectroscopy, fiber optics reflectance spectroscopy (FORS), and Raman spectroscopy. The resulting spectra can be found in this dataset. The pigments are referred to by their traditional Hindi names.

Transmission FTIR: Fourier-transform infrared spectroscopy (FTIR) in transmission mode was performed using a Bruker Vertex 70 infrared bench spectrometer coupled to a Bruker Hyperion 3000 infrared microscope. Pigments were compressed onto a diamond cell with a stainless-steel roller prior to analysis. Using the Bruker OPUS (version 6.0) software, spectra were recorded between 4000 and 600 cm-1 at 4 cm-1 spectral resolution and 32 scans per spectrum.

FORS: Spectrometer: Ocean Optics FLAME Visible/near IR spectrometer, range 350-1000 nm, typical optical resolution 1.33 nm. Halogen light source: Ocean Optics HIL-2000-FHSA. Reflection/backscatter fiber optic probe used to acquire data. Data acquired with Ocean Optics “OceanView” software.

Raman: Raman analysis was conducted using a Bruker Optics Senterra dispersive Raman microscope with an Olympus BX51M microscope equipped with 20x and 50x long working distance objectives and using the Bruker OPUS (version 7.5) software. The Raman spectrometer has three laser sources, 532 nm, 633 nm, and 785 nm. The optimum laser source depends on the pigment analyzed but in general, blue, and green pigments were predominantly analyzed with the 532 nm laser at 2 mW or 5 mW power and other colors analyzed with the 785 nm laser at 10 mW power. The exception is Menil (MCH.12), which was analyzed with the 785 nm laser at 1 mW power.