Cobalt yellow

/ ko • bawlt   yel • low /

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About the chemical structure:

Chemical name: potassium cobaltinitrite
Formula: K3[Co(NO2)6] · H2O
Refractive index: n/a


Color Index (C.I.) PY 40

How can you identify Cobalt yellow?


UVF: no

IRFC: blue

OM: at high magnification, tiny crystals and crystalline clusters appear.


It's identified by means of FTIR and Raman.

Raman spectra: University College London;

FTIR spectra: IRUG

Usage and handling:

Permanence: Toxicity:

Lightfast: excellent.

Degradation processes: it is rated as permanent in oils but darkens and fades easily in watercolors. However, the pigment was never popular as an oil color and is much more widely available as a watercolor.

toxic. Harmful by inhalation and if swallowed.

MSDS: Kremer


Artists’ Pigments. A Handbook of Their History and Characteristics, Vol. 1, L. Feller, Ed., Cambridge University Press, London 1986, p. 37-46