Interpreted digital swatch
A pale, opaque, distinctly green-leaning blue — the colour of a sky near the horizon rather than overhead. Cerulean is the specialist among blues, and painters keep it on the palette for one job that nothing else does as well.
Origin
A cobalt stannate, first described by the Swiss apothecary Albrecht Höpfner in 1789 and brought to market as an artists' colour by George Rowney in England around 1860. The name comes from the Latin caeruleum, which in Roman usage referred to blue pigments generally — Pliny uses it for Egyptian blue — so the modern name is a borrowed antiquity rather than a continuous tradition. Manufacture calcines cobalt and tin oxides together at high temperature, and tin makes it costly; some modern versions substitute chromium, sold as cerulean blue chromium, which is greener still and cheaper.[1, 2]
In art history
Because it appeared late and cost a great deal, cerulean has a narrow but distinct history: it belongs to the Impressionists and to everything downstream of them. Monet used it in skies and in water, Signac and the Neo-Impressionists valued it because its opacity holds a discrete dot of colour without bleeding into its neighbours, and it recurs through twentieth-century landscape and coastal painting. In this atlas it appears in seven eras, all of them after 1860 — one of the clearest examples in the database of a pigment acting as a date stamp. If a painting contains cerulean, it was not painted before the middle of the nineteenth century.[3]
In the studio
The characteristic that defines it is opacity. Most blues are transparent; cerulean is chalky and covering, which means it sits on the surface as a solid block of colour rather than glowing from underneath. That makes it wrong for glazing and right for the flat, matte, atmospheric passages where a transparent blue would go muddy. Its green bias makes it the natural blue for a horizon, for sea, and for skin in cool light. It is entirely lightfast, unaffected by alkalis — so unlike Prussian blue it can be used in fresco — and safe in every mixture. Its drawback beyond price is a certain deadness: overused, it flattens a picture.
Afterlife
Genuine cobalt-tin cerulean is still manufactured in small quantities and is among the more expensive artists' pigments. Most tubes sold today under the name are either the chromium version or a phthalo-and-white imitation, and the difference matters more here than with most substitutions: the imitations are transparent, and transparency is the one thing cerulean exists to avoid.
In different media
Cerulean or cobalt?
Both are cobalt pigments and both are permanent, but they are different compounds and they do different jobs. Cobalt blue (PB28) is cobalt aluminate. Genuine cerulean (PB35) is cobalt stannate, cobalt combined with tin, and cerulean blue chromium (PB36) is a cobalt chromite that leans greener still. On a tube, the Colour Index code is the only reliable way to tell which one you have.
Side by side, cerulean is the greener and paler of the two. Gettens and Stout describe it as the only cobalt blue without a violet tint, and it is the more opaque, with little tinting strength. Cobalt blue is a clean, slightly warmer mid-blue and semi-transparent in most paints. Neither overwhelms a mixture the way Prussian or phthalocyanine blue does.
In watercolour the difference is also one of texture: cerulean granulates, settling into the grain of the paper. Both resist light, acids and alkalis, and both have been used in every technique, fresco included. Monet used them together: in The Gare Saint-Lazare of 1877, cerulean, then new on his palette, is mixed with cobalt blue and synthetic ultramarine.[4, 5, 6, 7, 8, 9, 10]
By Pigmentoria · Published · Updated
Sources
- Höpfner, A. (1789). Vorschlag einer Bereitung zu einer beständigen blauen Farbe. Magazin für die Naturkunde Helvetiens 4. Orell, Geßner, Füßli und Comp., Zürich, pp. 41–47. archive.org/stream/magazinfrdiena04hp/magazinfrdiena04hp_djvu.txt
- Gettens, R. J. and Stout, G. L. (1942). Painting Materials: A Short Encyclopaedia. D. Van Nostrand, 1942; Dover reprint, 1966, s.v. Cerulean Blue. archive.org/details/paintingmaterial0000gett
- Roy, A. (1985). The Palettes of Three Impressionist Paintings. National Gallery Technical Bulletin 9, pp. 12–20, n. 11. nationalgallery.org.uk/media/15803/roy1985.rtf — on its arrival c. 1860 and on Monet, The Gare St-Lazare
- ColourLex. Cerulean blue. colourlex.com/project/cerulean-blue/
- Golden Artist Colors. Heavy Body Acrylic: Cerulean Blue Chromium (product data). goldenartistcolors.com/products/heavy-body-acrylic-color-cerulean-blue-chromium
- Winsor & Newton. Professional Watercolour: Cerulean Blue (product data). winsornewton.com/products/professional-watercolour-cerulean-blue
- Gettens, R. J. and Stout, G. L. (1942). Painting Materials: A Short Encyclopaedia. D. Van Nostrand, 1942; Dover reprint, 1966, s.v. Cobalt Blue; Cerulean Blue. archive.org/details/paintingmaterial0000gett
- ColourLex. Cobalt blue. colourlex.com/project/cobalt-blue/
- Winsor & Newton. Artists' Oil Colour: Cobalt Blue (product data). winsornewton.com/products/artists-oil-colour-cobalt-blue
- Roy, A. (1985). The Palettes of Three Impressionist Paintings. National Gallery Technical Bulletin 9, pp. 12–20, The Gare St-Lazare (1877). nationalgallery.org.uk/media/15803/roy1985.rtf
Others in this family: Ultramarine · Prussian blue · Cobalt blue · Azurite
Where it appears
Every era and artist in this atlas whose palette includes this pigment. Links are reviewed by hand, and those that are not a named use of the pigment are marked.