When chrome yellow was first introduced as a pigment in the early nineteenth century, it provided a bright, opaque yellow on the artists’ palette. However, it suffered a flaw in its original form—it darkened upon exposure to light.
Chrome yellow enjoyed a brief history of widespread use among nineteenth-century artists, such as Turner, Manet, Cézanne, Monet, and Pissarro. Cézanne, like Pissarro and Monet, used the neutralizing effect of combining three primary colors—ultramarine, vermilion, and chrome yellow—to make colored grays. (Callen, 2000) Its popularity soon faded because a more stable opaque pigment, cadmium yellow, was introduced in the middle of the century.
The Impressionists’ highly complex paint mixtures of primaries were solutions to the problems of rendering plein air light effects and modeling forms in space. Equivalents were sought in material colors for the effects of light because they realized ‘sunlight cannot be reproduced, but it must be represented.’ (Dennis, 1913) It is not so much the brilliance of each color that produces a high-key picture, as the juxtaposition of specific colors enhances each other’s color and brightness. Renoir noted this effect that every good colorist knows:
“I used chrome yellow which is a superb colour but which apparently plays nasty tricks. I tried cadmium [yellow]; I found great difficulties in using it, it made me paint heavy. Then I wanted to make my little Rubens. I began to paint with Naples yellow, which is a rather dull colour. It gave me all the brilliance I sought. But it’s the same story... It depends what I put around it.” (André, 1919)
By ‘nasty tricks,’ Renoir referred to the darkening of chrome yellow when exposed to light. Despite its brief history as an artist’s color, modifications to the original form of the pigment discovered in the middle of the twentieth century now make it lightfast and resistant to change.
Chrome Yellow Pigment
Chrome yellow is a yellow pigment made by adding a soluble lead salt (nitrate or acetate) to a solution of alkali chromate or dichromate. It is a crystalline mineral consisting of lead(II) chromate that can vary in hue from primrose yellow to orange, depending upon the particle size, which, in turn, depends on the precipitation conditions. Lighter hues like chrome yellow primrose usually contain lead sulfate or other insoluble lead salts. The middle hues are neutral lead chromate, and the orange chromes are basic lead chromate. The pigment consists of very fine particles that are dense and opaque.
The pure form of lead chromate is listed in the Colour Index (1971) as Pigment Yellow 34 (CI 77600), with the lead chromate-lead sulfate composition (chrome yellow primrose) listed as CI 77603.
| Chemical Name: | Lead chromate | |
| EC Number: | 231-846-0 | |
| CAS Number: | 7758-97-6 | |
| IUPAC Name: | lead(2+) chromate | |
| Molecular Formula: | PbCrO4 (CrH2O4.Pb) |
Permanence and Compatibility
When chemically pure, chrome yellow is moderately lightfast but is often observed to darken and become brown upon aging. (Weber, 1923; Doerner, 1934) According to Gettens, sometimes, especially when mixed with organic colors, it takes on a green tone by reduction of some of its chrome to chromium oxide (the basis of the green pigment, chromium oxide). (Gettens, 1966)
Greatly improved resistance to discoloration upon exposure to acids, alkalis, and light is possible by encapsulating the pigment with amorphous silica and other metal oxides. Since the coated pigment particle surface assumes the inert characteristics of silica, these pigments show superior resistance to light, chemicals, and heat. As reported by Kühn and Curran, modern lightfast chrome pigments (based on the monoclinic crystalline form) are encapsulated with silica and various metal oxides. (Kühn, 1986) These encapsulated varieties of chrome pigments are stable to light, high temperature, weathering, and resistant to sulfur dioxide.
Common types of chrome yellow may not be used with alkali binders, such as lime and water glass, because they are transformed into the red basic lead chromate. These varieties also tend to exhibit poor resistance to acids. Lead chromates can be compatible with all common pigments, although older references sometimes warned against mixing with chalk because of the latter’s basicity. However, encapsulated varieties of lead chromate pigments are highly resistant to acids and alkalis.
Toxicity
Although there are potential hazards to health from exposure to high concentrations of soluble chromate salts in industrial environments, there does not seem to be great alarm over risks in using the pigment in small quantities in paint. Because of its very low solubility in body fluids, using lead chromate in paints represents a lower potential hazard. [8] Of course, ingestion and prolonged breathing of the pigment dust should be avoided.
Crocoite mineral specimen from the Dundas extended mine, Dundas, Tasmania, Australia. Photograph of a specimen from the Willems Miner Collection by J.J. Harrison.
Origin and History
Chromium was first extracted from the mineral crocoite by the French chemist Nicolas Louis Vauquelin in 1797. He described the preparation of lead chromate in his 1809’ memoir’ (Annales de Chimie, LXX, p. 90–91). He mentioned that it could be prepared in different hues depending on precipitation conditions. Although first produced in 1804, it was reported that it did not come into commercial production until 1818. [9] Maerz and Paul report the first recorded use of chrome yellow as a color name in English was in 1818. [10] Raft mentioned the purchase of chrome yellow (‘juane de chröme’) in 1815 by Danish painter C. W. Eckersberg (1783–1853), [11] and this appears to be the first mention of the pigment in art literature. [12] Zerr and Rübencamp discuss several mixed chrome pigments that were ‘put on the market under the names new yellow, Paris yellow, Baltimore yellow, American yellow, &c.’ [13]
Sir Thomas Lawrence, c.1825, later copy by Richard Evans of an unfinished self-portrait by Lawrence, the palette and brushes added by Evans, c.1868, National Portrait Gallery.
Chrome yellow is found primarily in paintings of the nineteenth century. Kühn reports the earliest use of chrome yellow in the painting Portrait of a Gentleman by Sir Thomas Lawrence, dated before 1810, [14] which means that the production of the color was earlier than reported by others. George Field (1777–1854) was one of several leading chemists and colormen in the first half of the nineteenth century who were seeking more permanent colors, whether naturally occurring or, increasingly, chemically produced. He had a good working relationship with Lawrence and examined colors for him, as he did for other prominent artists. [15] Lawrence brought Field samples of ‘Paris Yellow’ or chrome yellow. [16] Liebig says it was an expensive pigment sold under the name ‘Cologne yellow.’ [17] Laurie says that Turner used chrome yellow and chrome orange. [18] It is found in works by other nineteenth-century painters, such as Böcklin, Cézanne, and Gauguin.
Because the pigment introduced in the nineteenth century tends to darken on exposure to light over time, and it contains lead, a toxic, heavy metal, it has been replaced mainly by cadmium yellow (mixed with enough cadmium orange to produce a color equivalent to chrome yellow). Cadmium pigments on their own are toxic as well from the cadmium content and are themselves being replaced with azo pigments. As a result, chrome pigments slowly have been dropped from the range of commercial artists’ paints; the last known commercial manufacturer to feature it in their 2008 literature was Sennelier.
For much of the twentieth century, yellow chrome pigments were used in traffic paint, road signs, and American school buses. [19]
Pigment Preparation
Lead chromate is prepared by precipitation of neutral solutions of lead salts with chromate or bichromate solutions, the method of precipitation remaining essentially unchanged since the early nineteenth century. (See United States Patent 2,023,928, filed on October 10, 1932.) In the 1960s and 1970s, patents were issued describing new methods of producing lead chromate pigments that encapsulated them in silicate or other metals to increase their lightfastness and chemical resistance. (See, for example, United States Patent 3,370,971, issued on February 27, 1968.) The encapsulated pigment contains 22% silica as a continuous film of dense amorphous silica surrounding the individual particles of lead chromate. When dispersed in paint and exposed to light, the pigment coated with silica is highly resistant to darkening, whereas the untreated product darkens seriously under the same conditions. Silicate-coated chrome yellow pigments are used to make Rublev Colours chrome artists’ oils.
Use in Mixed Pigment Colors
Chrome yellow is mixed with Prussian blue to form the color mixtures known as ‘chrome green’ and ‘cinnabar green.’ The pale tones of chrome yellow make chrome green, while medium chrome yellows can be used to make cinnabar green.
Rublev Colours Chrome Yellow Artists Oils
Chrome yellows offer several advantages as an artist’s oil paint. Compared to cadmium yellow and azo yellow, chrome yellows make dense, opaque paints that brush out long and flowing, yet the brush marks hold their shape.
Owing to its high refractive index of 2.3 to 2.7, lead chromate possesses good hiding power (opacity). The pigment’s high tinting strength allows pure lead chromate to be diluted with extender pigments. The medium chrome yellows, which usually contain a minimum amount of lead sulfate, tend to have the greatest opacity and tinting strength.
Lead chromates dry moderately well, although chrome yellow primrose dries slower than the light and medium varieties. It is known that they enhance the film-forming qualities of oil paints. Interestingly, lead chromate pigments do not form lead soaps in the process.
Lead chromates disperse well in oil and have very low oil absorption—ranging from 16% to 27%. When ground in oil, chrome pigments do not readily separate if the pigment is well dispersed. This is an advantage because pigment stabilizers are not necessary to make a paint that stores well and provides a paint with the maximum pigment load possible.
Rublev Colours introduced Chrome Yellow Primrose as an artist’s oil paint in August 2010 and Chrome Yellow Light and Chrome Yellow Medium in July 2013. All chrome yellows in Rublev Colours Artists Oils use the encapsulated pigment type that is lightfast and resistant to acids and alkalis. The three chrome yellows offered by Rublev Colours in linseed oil are:
Rublev Colours Chrome Yellow Primrose Artists Oil
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Note: The scan of the “drawdowns” (above and below) contains a pre-mixed paint film of 6 mils (0.006 inches) thickness applied to a standard test card to examine color consistency, opacity, and other qualities. The horizontal black bar on the test card shows the color’s relative hiding power (opacity). The drawdowns show the full-color strength (mass tone) on the left and mixed in a 1:2 ratio with titanium white on the right. The bottom area of the drawdowns is scraped to show undertones.
Rublev Colours Chrome Yellow Light Artists Oil
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Rublev Colours Chrome Yellow Medium Artists Oil
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References
(Callen, 2000) Callen, Anthea (2000) The Art of Impressionism. Painting technique and the making of modernity. New Haven and London: Yale University Press, p. 157.
(Dennis, 1913) Denis, Maurice (1913) Theories, 1890–1910, 3rd edition. Paris, p. 245.
(André, 1919) André, Albert (1919) Renoir, p. 22.
(Weber, 1923) Weber, F.W. (1923) Artists’ Pigments. New York: D. Van Nostrand Co., p. 40.
(Doerner, 1934) Doerner, Max (1934) The Materials of the Artist and their Use in Painting. New York: Harcourt, Brace, and Co., p. 63.
(Gettens, 1966) Gettens, Rutherford John; Stout, George Leslie (1966) ‘Chrome yellow.’ Painting Materials: A Short Encyclopaedia. New York: Dover Publications, p. 106.
(Kühn, 1986) Kühn, Hermann; Curran, Mary (1986) ‘Chrome Yellow and Other Chromate Pigments.’ Artists’ Pigments. A Handbook of their History and Characteristics. Washington, D.C.: National Gallery of Art and Cambridge: Cambridge University Press, p. 191.
8. Imperial Chemical Industries. Lead Chromate Paints, the Facts (1981).
9. De Wild, A. Martin (1929) The Scientific Examination of Pictures. London: G. Bell and Sons, Ltd., p. 69.
10. Maerz and Paul (1930) A Dictionary of Color. New York: McGraw-Hill, p. 192; Color Sample of Chrome Yellow: Page 43 Plate 10 Color Sample L4.
11. Raft, A. (1973) ‘Eckersberg’s farbekob i Rom.’ Meddelelser fru Thorvaldsen’s Museum 15–17, p. 152–154.
12. Kühn (1986) ibid., p. 189.
13. Zerr, George; Rübencamp, R. (1906) A Treatise on Colour Manufacture. 1st edition. Mayer, C. (ed.) London: Griffin & Co., Ltd., p. 149.
14. Kühn (1986) ibid., Notable Occurrences from the Bayerische Staatsgemäldesammlungen, p. 213.
15. Harley, R.D. (1979) ‘Field’s Manuscripts: early 19th-century colour samples and fading tests.’ Studies in Conservation, Vol. 24, p.79–83.
16. Gage, John (2001) ‘A Romantic Colourman: George Field and British art.’ Walpole Society, Vol. 63, p.1–73.
17. Liebig, J.; Poggendorff, I.C.; Wöhler, F. (1842) Handwörterbuch der reinen und angewandten Chemie. Braunschweig.
18. Laurie, Arthur Pillans (1935) New Light on Old Masters. Sheldon Press, p. 44.
19. Worobec, Mary Devine; Hogue, Cheryl (1992) Toxic Substances Controls Guide: Federal Regulation of Chemicals in the Environment. BNA Books, p. 13.
