Cobalt Blue

Cobalt Blue is a Series 6 semi-transparent color. It has a masstone of a deep purple blue, with a vivid blue undertone. This color is available in 80ml, 250ml and 500ml sizes.

Color Detail



Blended with Titanium White

Washed with water

Color Comparisons

Cobalt Blue and Cobalt Blue Hue

The two colors are very similar, but it just is not possible to accurately imitate the true Cobalt Blue pigment. The imitation is as closely accurate as we have been able to get it but when side by side three is a difference.

Cobalt Blue

Cobalt Blue Hue

Cobalt Blue / Cobalt Blue Hue

Comparing Blues

The top colour is the standard shade of Pthalo Blue which is the green shade, the second colour which looks very similar in masstone is the red shade of Pthalo Blue and when the two colours are tinted out and shown side by side it is easy to imagine how some artists might want to use both, and others might possibly change their choice of only one Pthalo Blue after seeing this comparison. If we move down from the red shade of Pthalo Blue we have Cobalt Blue which is much redder than the red shade Pthalo Blue when seen side by side, but the less well known shaded colour called Pacific Blue is much redder again to the point of being almost purple rather than blue and of course Ultramarine Blue sits somewhere in between these two. Most landscape artists would cross compare the pale tints of these colours when assessing what they might like to have on their palette for painting skies. The second swatch of four colours shows them diluted for glazing and the differences in the character of the the colour is easy to see. What is not really apparent on a computer screen is that Cobalt Blue has a sort of built in luminosity which is lacking in Cobalt Blue Hue and therefore true Cobalt Blue is sometimes used in an over painting layer over Cobalt Blue Hue.

The next chart shows the same four colours used as thin glazes. When seen applied as a glaze it is easy to see the difference between the two Pthalo pigments while Cobalt Blue which is a semi transparent colour is of course redder, and it does seem to have the ability to enhance the colour if true Cobalt is used thinly on top of Cobalt Blue Hue. The Pacific Blue which is a fairly opaque would not normally find much use as a glaze.

Pthalo Blue

Pthalo Blue Red Shade

Cobalt Blue

Pacific Blue

Pthalo Blue glaze

Pthalo Blue Red Shade glaze

Cobalt Blue glaze

Pacific Blue glaze

Color Information

  • Chemical Description: Oxides of Cobalt and Aluminium
  • Pigment Type: Inorganic
  • Lightfastness: 1
  • Permanency: Excellent
  • Pigment Strength: Medium
  • Colour Index Name: PB 28
  • Opacity or Transparency: Semi-transparent

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