Updated on 20 February 2017 (Harvard referencing).
16 April 2016. Two days ago I found the time to finish the series on mixing colours with exercise 4. I managed to produce a fairly satisfying Chevreul’s colour circle (see Fig. 1a below, apart from primary yellow and primary blue all colours in the photo are close to the original). What I tried when mixing the primary colours was to create a feeling of identical “steps” from one hue to the next. I could not say what made me decide to mix in a little more of the one colour and less of the other and I could not describe with confidence the characteristics which would describe such a step. It was an intuitive decision and it may well be that the colours in the circle do not look evenly distributed to anybody else.
What I noticed in my own circle as compared to Chevreul’s (Fig. 1b) was its artificial look. The colours look too clean and too cleanly separated for my own liking. Although the copies of Chevreul’s colour wheel found on the internet will almost certainly not reproduce the original hues with fidelity and from what is visible, the hues are not evenly spaced, I prefer his work by far. It radiates the sensitivity of someone whose lifelong profession was colour.
Figure 1a. Own colour circle after Chevreul, 12 hues
Following the instructions in the study guide on mixing complementary colours while keeping tonal values (hopefully) constant I achieved the following result (Fig. 2):
Figure 2. Mixing complementary colours
The first thing I noticed in the series was that (in my opinion) most of the resulting mixes would not count as grey. The only mix I would place in the category was that between primary yellow and violet. It turned a beautiful cool grey with admirable ease which also stayed equal in tonal value with respect to that of the original hues. In stark contrast to this was the mix between orange red and blue green, which became a very dark murky green. On the colour circle the axes of these two pairs pairs lie at 90° relative to each other. Tonal values of the other mixes appear to lie in between these two extremes. I also noticed that, of course, there would be several other hues achievable with each pair depending on their relative proportions in the mix. What I tried to do, however, was to produce a mix which came closest to be called grey. As in the previous exercise on mixing colours while keeping tonal values constant there was again a huge difference in the amount of white to be added to the respective darker tone.
Updated on 20 February 2017 (Harvard referencing).
12 April 2016. Since the exercises on mixing colours are intimately connected, I waited until I had completed all of them in order to write a summary of the experience, which, as has been noticed by a number of fellow students before, required the input of
enormous amounts of paint and time. In return it gave a growing understanding of the nature of colour and, in the case of some of the experiments, a near-meditative peace of mind.
Exercise 1: Mixing greys – anachromatic scale
Since I had no previous experience whatsoever regarding the proportions of white and black needed in producing a sensible number of steps for the above scale, I started ever so carefully, adding only minute quantities of black each time. This resulted in a relatively impressive 64 shades in total (see Fig. 1 below). At the dark end of the scale the differences are unfortunately very difficult to see in the photo. With my limited knowledge of photo editing I made things not much better, but in nature there is a continuous darkening visible. Interestingly, I went through three cycles of mixing in black and adding to the darker end of the scale before my eyes/brain would agree that NOW there was a real difference to the shades put on before. When, in the end, looking at the result, the scale went smootly from white to black.
Figure 1. Anachromatic scale using ivory black, 64 steps
Taking two small pieces of paper with neutral grey and placing them on both ends of the scale as advised in the study guide, revealed that the same tone looks darker near white than near black (Fig. 2a and 2 b below). According to Chevreul’s idea that the brain tends to exaggerate differences in tone in order to allow a clear differentiation – see my previous post on Chevreul’s colour theory (Lacher-Bryk, 2016). I assume that probably the real differences may be less prominent on both ends of the scale.
Figure 2a. Light end of the scale comparing neutral grey
Figure 2b. Dark end of the scale comparing neutral grey
The neutral grey produced in the above exercise I then used to prepare an A2-sized ground on acrylic paper. Despite having assumed that I had mixed my grey very thoroughly I noticed differences in tone across the ground. So I made a mental note that it would be necessary to work extremely thoroughly with totally clean tools to achieve acceptable results during the exercises to follow. It took me two whole days to complete the experiments below and left me with literally kilograms of little heaps of mixed paint. Since I have no use for them in the near future it will mean having to discard them with mixed feelings. So I took a souvenir photo of the lot (Fig. 3):
Figure 3. Leftover colour mixes
The following photo shows an overview of the colour mixing exercises (Fig. 4):
Figure 4. Results of the colour mixing exercises
Exercise 2: Primary and secondary colour mixing
To be honest, I am the owner of only a few hues of acrylic paint. I like mixing and I have accumulated some intuitive experience in decades of watercolour painting. Of course, there are some important differences when mixing acrylic paint when compared to watercolour, in particular the source of white mainly as paper white in the one case, and white pigment in the other.
So here is my modest selection of primary colours (Fig. 5):
Figure 5. My primary colours
In the case where I had only two hues of a colour (yellow and red) swapping their positions had no effect regarding the perceived relative tone, but in my opinion it does make a difference to the story told by the hues, tiny as it may be, when reading from light to dark or vice versa. With the blues, however, the primary blue (cyan) looks lighter when placed between two darker colours (ultramarine and bluegreen in my case) than when it sits to the side of the darker hues. The most intense hues of the above were primary red, Naphthol red deep and primary blue (cyan), so I used these in the following mixing experiments (Fig. 6):
Figure 6. Primary colour mixing: top – yellow to red, middle – yellow to blue, bottom – red to blue
The first thing I noticed when comparing the three sets of scales was that identical handling does not produce scales of equal length. While the change from yellow to red was achieved comparatively quickly and the mixes on the red side of the scale look relatively similar (not only on the photo but also in reality), the change from yellow to blue produced an enormous variety of clearly different greenish hues. I even ran out of paper at the end of the scale and had to stop it more abruptly than intended. The mix between red and blue produced did produce some of the murky dark mix mentioned in the study guide, although I would rate some of the hues towards the blue end of the scale as something like violet.
Still, testing other combinations of blue and red in order to make more believable violets gave the following results (Fig. 7). The photo, unfortunately, does not faithfully reproduce the hues especially in the top row, but the most convincing results came from primary magenta mixed with primary blue (bottom row).
Figure 7. Mixing violets: top – Naphthol red deep and ultramarine, middle – primary magenta and ultramarine, bottom – primary magenta and primary blue
The most time and paint-demanding experiments of this exercise were those aimed at mixing secondary colours in the above manner but trying to keep tonal values constant. I continued mixing in the second colour plus white until the hue of the white+colour mix was the same as the original second pigment. A whole day was devoted to the following three scales (Fig. 8):
Figure 8. Mixing secondary colours while keeping tonal values constant: top – yellow to red, middle: yellow to blue, bottom: red to blue
The first thing to mention here is that I may have misinterpreted the instructions. I don’t know whether I may have been required to mix in some white with the starting primary colour, too. I did not and in the case of yellow as starting colour this meant that I had to add ten times the amount of white, and sometimes far more, with each tiny blob of secondary colour in order to keep tonal values constant. This also meant discarding enormous amount of paint each time I started another hue. Interestingly, the same effect was not noticeable after two thirds of the red to blue scale. There were 12 steps in the scale and no white had to be added after step 8. I have no valid explanation for the phenomenon yet, but maybe the red in this case has a slightly darker tonal value than the blue, so when having got rid of the difference by mixing in white for a while, the adding of more blue would not make any further changes to the overall tonal value. Or it may be my eyes, which are not yet expert at recognising small tonal differences with certainty. However, although I can see some fluctuations, I am quite pleased with the outcome. Considering the differences in darkening through drying in different hues of acrylic paint I was surprised to see a relatively smooth result. The brownish grey I was supposed to see halfway through the red to blue scale according to the study guide was not really there apart from the third mix from the left, but I may have msjudged the amount of colour to mix in in the first step, so there is a chance of having missed some information here simply by low resolution.
Exercise 3: Broken or tertiary colours
In the last exercise, requiring the mixing of secondary colours, the occurrence of grey was perfectly visible in the case of a scale between orange red to green blue, but was completely missing in the transition from sap green to vermilion. Maybe the mustard colours to the right of the sap green count as broken or tertiary colours without being grey. They certainly lack chroma when compared to the original colours (Fig. 9).
Figure 9. Mixing secondary colours while keeping tonal values constant: top – orange red to green blue, bottom: sap green to vermilion
A phenomenon I noticed in all the mixing experiments was the different qualities of the colours chosen to mix, which resulted in skewed transitions in some instances. For example, in the mixing of primary colours the transition from yellow to red was fast, so that most of the scale I would describe as reddish. The same effect was visible in e.g. the transition from yellow to blue shown in the second photo from the bottom, second row, and in the last of all mixes from sap green to vermilion. I would tend to describe the scale as orange-dominated. It would be interesting to have other people look at the scales to see whether their perception matches my own.
Experimenting in this way was a major hint regarding both the incredible properties of colour and the power of human perception. It also makes my head swim to think of the worlds I need to discover yet. No wonder we are all addicted to colour.
Updated on 19 February 2017 (Harvard referencing).
3 April 2016. Michel-Eugène Chevreul (1786-1889) was a multi-talented, ingenious chemist in 19th century France, who, after having been urged to investigate the reason for the apparent turning grey of high quality yarn used in the making of tapestries, devised a groundbreaking classification of colours, a chromatic circle (Fig. 1), to serve as first-ever standard for weavers and dyers. It was and still is being adapted and extended by many contributors (Costa, 2009).
Figure 1. Michel-Eugène Chevreul (1861) Chromatic circle. Source: Michel-Eugène Chevreul [Public domain] via Wikimedia Commons
The original trigger for his research had been one observation where the nature of blacks appeared to change when seen next to blues and violets in tapestries. After doing some research on that major problem Chevreul came to the ingenious conclusion that colours set next to each other mutually influence the perception of their respective nature. Chevreul described this main observation as the Law of Simultaneous Contrast of Colours, stating that “In the case where the eye sees at the same time two contiguous colours, they will appear as dissimilar as possible, both in their optical composition and in their strength of colour” (emphasis added by me). It was first published in an English language translation of his 1839 book, “The Principles of Harmony and Contrast of Colours and their Application to the Arts” (1855) (Roques, 2011, p. 4).
The above statement was interpreted by Chevreul as a tendency of the brain to enhance perception by exaggerating differences in lightness and hue, in particular along the common border (Roques, 2011, pp. 4-5, for the effect on lightness see top row in Fig. 2 below). The same works also for the bottom image in the same illustration. In the row of increasingly dark stripes the different borders to the left and right of each stripe will make them resemble “channelled grooves more than plane surfaces”. This effect is known as “Chevreul’s illusion”.
Figure 2: Redrawn detail from original by M.-E. Chevreul (1839) Illustration of the contrast of lightness. Source: Georges Roques after M.-E. Chevreul (1839) [Public domain] via Roques (2011)
When the law is applied to hue, the following effects are observed: Placing side by side narrow strips of different tones of the same colour or strips of the same tone in different colours influences both the perception of intensity (contrast of tone) and optical composition (contrast of colour) of each colour, hence the name “simultaneous contrast of colours” (Roques, 2011, p. 6).
The basis of the perceived modifications depend upon the concept of complementary colours first observed by Buffon in 1743 (e.g. after staring at a red dot for some time, it will appear green when moving the eye to a white sheet, Roques, 2011, p. 7) and observations by Hassenfratz regarding coloured shadows created by the simultaneous use of two different light sources (Roques, 2011, p. 7). Chevreul considered, in line with his observation for lightness, that complementary colours are those which are the most opposed. Exaggerating differences in this context means that the brain will add to each of the juxtaposed colours a little of the colour complementary to each. A white pattern on coloured grounds will thus appear tinted with the colour complementary to that of the ground. Adding some of the background colour to the pattern influenced by the complementary colour will neutralize the effect. And, importantly, juxtaposing complementary colours has the effect of enhancing each other, since to each is added some of itself (Roques, 2011, pp. 8-9).While the basic physical mechanisms of colour perception are not disputed and Chevreul’s explanations are supported by findings in neuroscience, there exist several conflicting theories regarding the mutual influence of colours and their effect on the perception of colour in art (Roques, 2011, p. 9), while a main point of criticism is that according to modern standards Chevreul confused additive and subtractive mixing, the former referring to mixing light, the latter to pigments and which are incompatible (Roques, 2011, p. 10). It is also important to remember that the observed effects depend on the size (area) of the coloured samples. In cased the samples are very narrow, the colours will “fuse” to be perceived as an average between the two juxtaposed colours (Roques, 2011, p. 11).
Chevreul’s work, increasingly so as he moved from pure to applied science, was of immense interest for whoever used colour at the time. Since, however, many workers of the time became acquainted with Chevreul’s theories in a second-hand fashion there were some misunderstandings transported regarding their true nature and some artists adopted a style of painting based on misinterpretations (Roques, 2011, pp. 12-13). Interestingly it was mostly artisans, and not painters, who appreciated Chevreul’s findings when solving practical problems. Painters were only interested in the enhancing effect of juxtaposing complementary colours and tended to ignore the unwanted effects in other colour pairs. Among the painters interested in Chevreul’s findings was Eugène Delacroix (1798-1863, France) (Fig. 3). The example below is a good example of applying complementary colours, see especially the flags on the ground (Roques, 2011, p. 16):
Figure 3. Eugène Delacroix: “Entry of the Crusaders into Constantinople”, 1840, oil on canvas. Source: Eugène Delacroix (1798-1863) [Public Domain] via Wikimedia CommonsDespite contrasting opinions it is obvious that many painters deliberately applied their knowledge regarding the use complementary colours, e.g. Impressionist Claude Monet (1840-1926) or Impressionist and Neo-Impressionist Camille Pissarro (1830-1903) in the following painting, where the juxtaposed greens and reds assume a great brilliance. He even went as far as taking in Chevreul’s advice to pay attention to the effect the colour of the frame has on a painting.
Camille Pissarro: “The Red Roofs”, 1877, oil on canvas (source: Wikimedia Commons)
During Neo- and Post-Impressionism painters became increasingly interested in the organisation of colours on the canvas. Among these, Neo-Impressionist and theoretician Paul Signac (1863-1935) and Georges Seurat (1859-1891) were most avid in their application of Chevreul’s colour theory, especially when “optically mixing” by placing small dots of complementary colours next to each other. According to Roque (p. 18) there was another misunderstanding at the base of their idea: rather than enhancing the respective complementary colour, the effect would be one of averaging them out, since they did not take into account Chevreul’s warning of not confusing contrast and mixing, the presence of which depends on the size of the sample of colour. The luminosity remains in their paintings, because the dots are big enough for optical mixing NOT to work (Roque, p. 19).
Georges Seurat: “The Seine and la Grande Jatte – Springtime 1888″, oil on canvas (source: Wikimedia Commons)
Vincent van Gogh (1853-1890) was another painter with a keen interest in colour theory. Since he had a great liking for yellow, many of his paintings have juxtaposed a large proportion of the complementary colour, violet, e.g.:
Vincent van Gogh: The Café Terrace on the Place du Forum, Arles, at Night, 1888, oil on canvas
Roque, on p. 21, discusses also van Gogh’s description of the ideas behind the famous painting of his bedroom, on the base of which was an interest in transporting an impression of rest by the selective use of colour. To this end van Gogh used both the contrasts of complementary colours AND the same hues in different states.
Chevreul’s ideas continued to be of interest with the beginning of abstract art. Since the latter artists has a particular interest in the organisation of colour on the canvas, his theory helped them organise their ideas. Foremost among these was Robert Delaunay (1885-1941), who used it to systematically structure his abstract paintings. His intention was to capture colour vibration and transport it to the eye of the viewer by applying a phenomenon which Chevreul called “mixed contrast”: Seeing one colour, followed by the illusion of its complementary, superimposed on the colour of another object introduced at a later point in time.
Robert Delaunay: “Le Premier Disque”, 1912-1913, oil on canvas (source: Wikimedia Commons)
Despite an increasing tendency to challenge and replace Chevreul’s ideas with newer findings, they are still in use as a basis of teaching colour theory today (Roque, p. 24).
References:
Costa, A.B. (2009) Michel-Eugène Chevreul. French Chemist [online] Encyclopaedia Britannica. Available at: https://www.britannica.com/biography/Michel-Eugene-Chevreul [Accessed 3 April 2016]
![Figure 1b. Chevreul's colour wheel, 72 hues. Source: Michel-Eugène Chevreul (1883) [Public domain] via Wikimedia Commons](https://andreabrykocapainting1.files.wordpress.com/2016/04/chevreul_colour_wheel.jpg?w=343&h=327 "Chevreul_colour_wheel")
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