Pigments through the Ages - Technical Information

About the chemical structure:

Chemical name:	magnesium euxanthate
Formula:	C₁₉H₁₆O₁₁Mg · 5 H₂O
Refractive index:	above 1.52

Color:

Color Index (C.I.)

this is not considered a pigment anymore because of the banned production method

How can you identify Indian yellow?

Imaging:

UVF: yellow

IRFC: pale red

OM: yellow crystalline particles with a deep rich,translucent orange/yellow hue. Anisotropic and exhibiting weak birefringence. Particles can vary greatly in shape depending up on their manufacture from rods to spherulite to appearing like a gel. Particles can vary in size from 1-30μm.

Microscopic appearance at x500 mag

Analytics:

It's identified by means of FTIR and Raman. It is decomposed by hydrochloric acid. When burned, it should leave white ashes, as many organic substances do.

Raman spectra: University College London;

FTIR spectra: IRUG;

Usage and handling:

Permanence:	Toxicity:
lightfast: good Degradation processes: it was used in both oils and water based mediums, however direct sunlight will result in slight photoxidation and therefore fading.	non toxic. It is no more commercially available

Permanence:

Toxicity:

lightfast: good

Degradation processes: it was used in both oils and water based mediums, however direct sunlight will result in slight photoxidation and therefore fading.

non toxic. It is no more commercially available

Literature:

Artists’ Pigments A Handbook of Their History and Characteristics, Vol. 1, L. Feller, Ed., Cambridge University Press, London 1986, p. 9-36

Baer, N.S., Indictor, N. and Joel, A. The Chemistry and History of the Pigment Indian Yellow, Conservation and the Graphic Art, 1972 Congress of the International Institute of Conservation, Lisbon 1972, p. 401-408