Cobalt Green Professional Watercolour – 15ml Glass Jar

Description

Cobalt Green Professional Watercolour is prepared using the inorganic mixed metal oxide spinel structured pigment, cobalt (II)/nickel (III)/zinc titanate. The pigment has been selected for its purity, light fastness and intense cool green hue, making it ideal for use in A J Ludlow’s Professional watercolour range.

Cobalt Green is often thought as being synonymous with Rinmann’s (or Rinman’s) Green. It is named after the Swedish chemist, Sven Rinman, who discovered the green cobalt zincate pigment in 1780. The colour is described as a dull yellowish green by the Colour Index, who classify the pigment as C.I. 77335, (pigment green 19) and describe its structure as an “isomorphic mixture of cobalt zincate and zinc oxide which cannot be chemically separated” (Pigment Compendium, page 120). It was an unpopular pigment with artists as it was expensive to buy and not particularly strong (Pigment Compendium, page 329). Rinmann’s Green is also referred to as Zinc Green¹ and is similar to Gellert Green, which was made by using a different method.

Modern cobalt green pigments (classified as C.I. pigment green 50, C.I.77377) are formed by the incorporation of cobalt into various metal titanate spinels, to produce a range of cobalt pigments, whose colours range from bluish-green to green. In A J Ludlow’s Professional Watercolour range the bluish-green pigment (Cobalt Turquoise) is composed of cobalt (II)-nickel (III) titanate, whilst the green coloured one (Cobalt Green) is a complex mixed metal titanate of cobalt, nickel and zinc. These modern pigments are much brighter and have greater tinctorial strength than the original cobalt zincate greens, Rinmann’s and Gellert Green.

Although containing cobalt and nickel, these metals’ bioavailabilty in the pigment used in our watercolour is very low and so the pigment is considered safe for use in our Professional watercolour range.

Notes:

¹ It should be noted that the inorganic pigment mixture of zinc chromate, Prussian blue and barytes (C.I. pigment green 16, C.I.77955 + 77525 or 77007) is also known classically as Zinc Green.

Eastaugh N, Chaplin T, Siddall R, Walsh V, “Pigment Compendium: A Dictionary and Optical Microscopy of Historic Pigments”, Routledge, Abingdon 2013

Pigment Details: Cobalt-Nickel-Zinc Titanate / Colour Index Pigment Green 50 (C.I. PG50)