Cobalt Blue

Pigment Blue 28

Cobalt Blue.

Cobalt Blue (cobalt oxide of alumina, cobalt ultramarine, Thénard’s blue, royal blue, cerulean blue), blue pigment, consists primarily of cobalt aluminate CoAI2O4 and is obtained by glowing a mixture of phosphate of cobalt oxide with alumina hydrate or of alum with sulphate of cobalt. Cobalt blue prepared from cobalt oxide and alumina hydrate forms Leiden (Leithen) Blue, Vienna Blue. Cobalt blue has a reddish cast, but when prepared with the addition of zinc oxide it is true blue. It is similar to ultramarine, but much more stable, highly saturated, not fully opaque and appears violet in lamplight. It is used especially in glass and porcelain painting. It is denoted by U on blue colour works: FFU fine fine cobalt blue, MU medium cobalt blue and OU ordinary cobalt blue.

Single Pigment Colours

A small overview of cobalt blue (PB 28) single pigment colours suitable for miniatures, models, and dioramas.

Mixed Pigment Colours

  • Cobalt Blue RAL 5013, glossy, Dupli-Color Acrylic Spray
  • Cobalt Blue, translucent, Marabu Artist Acrylic 954

Source: Meyers Großes Konversations-Lexikon, 6. Auflage 1905–1909