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Approaching Colour Mixing

Date: 28-02-2023
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There are many diverse approaches to colour mixing, shaped by our understanding of colour, and what our desired approach and results are.

2400 years ago, Classical Greeks saw colours as existing between the poles of light and dark, and counted five Primary colours occurring, with Green placed “naturally”, according to Aristotle, in the centre.

Around 400BCE in Greece, colour specificity was not so important; what mattered was light and dark, and the colours fell between these two extremes. This makes sense when we think how lives were governed completely by the rising and setting of the sun, where a wick floating in a dish of oil was the only illumination after nightfall. Between white and black, Aristotle placed five hues: Yellow, Red, Green, Blue, and Violet.

Nearly two centuries later, artists such as da Vinci still located colours between the poles of white and black. There was no colour theory as such; colours had attributes and were used symbolically. We can read this concern for dark and light in da Vinci: “of several colours, all equally white, that will look whitest which is against the darkest background. And black will look most intense against the whitest background. And red will look most vivid against the yellowest background; and the same is the case with all colours when surrounded by their strongest contrasts”.

Newton’s spectrum was the result of scientific process, but his counting of seven colours was based on ideas of divinity. Green maintains its central position.

It wasn’t until Sir Isaac Newton (1642-1727) passed white light through a prism, splitting it into the spectrum of colours, then passed it back through another prism, returning it to white light, that concrete theories developed around colours. Newton showed that colours existed in a visible range between Red and Violet, and he described seven hues: Red, Orange, Yellow, Green, Blue, Indigo, and Violet. It wasn’t long after Newton’s Opticks (1704) was published that the first colour wheel was developed by Frenchman Claude Boutet in 1708, showing seven colours (Yellow, Orange, Fire Red, Crimson, Violet, Blue and Green) and suggesting mixing around the wheel to achieve colour harmony.

The three-colour system using the Primary hues of Yellow, Red and Blue was laid out in 1726 by German Jacob Le Blon, and by the beginning of the 19th Century, painters were well acquainted with using this and the Secondary hues of Orange, Violet and Green. In England, Mary Gartside (1755-1819) became the first woman in the Western world to publish a book on colour and discuss colour theory in it. She also classified colours in warm, cool, and light colours, as well as the need to harmonise tints with regard to painting.  The colour wheel had become an important tool for navigating colour.

 

Some of the earliest colour wheels: Claude Boutet in France 1708, Mary Gartside in England 1808, and Goethe in Germany 1810.

Not everyone was thrilled by this. The German polymath Goethe rallied against such a cool analytical approach with colour being determined solely by light, stating that colour is grounded in human experience, as well as elements of light and darkness. Goethe was one of the first to systematically explore colour and colour theory, of how colours are perceived and how they interact with other colours. Unlike Newton, Goethe argued that colour needed darkness, and some colours were made with elements of darkness. JMW Turner (1775-1851) agreed with him, situating all colours between light and dark, just as the ancient Greeks had done.

While Newton was right about the colours formed by visible light, where varying frequencies of light come together to produce colours in a process called additive mixing (the process used by phone and video screens, and movies), Goethe was more correct when it came to mixing colours from paint. When you mix paints, the result is always darker through a process called subtractive mixing, as each addition subtracts wavelengths of light. To get light back into the mixture, we have to add white: “The addition of white is the addition of light,” said Vincent van Gogh.

Arranging colours in order of how active or passive they are allows us to see their placement in the picture plane, with warm hues advancing and cool hues receding relatively, and their corresponding emotional measure.

Aligning colours with human experience gained in popularity with the growth of abstract painting at the start of the 20th Century. Rather than placing hues on a colour wheel, Wassily Kandinsky (1866-1944) placed them between two opposing poles based on their energy, how active or passive they were. At one extreme was Yellow, the brightest, most energetic hue; at the other was Blue, the deepest, most contemplative hue. In the centre, just as in Aristotle’s time, was Green, being a combination of Yellow and Blue; though one can have a more active yellow-green or a more passive blue-green. Kandinsky found that assigning hues an emotional power allows painters to create works “which directly influence the soul”.

Of course, what we need from our palette is not only influenced by our own understanding of how colours work, but by what we are trying to achieve. Painters working in monochromes, such as Yves Klein (1928-1962) in Blue and Ad Reinhardt (1913-1967) in Blacks, are not going to have the palette of a portrait painter, as they have different paths and desires. A painter’s palette becomes more refined as they gain experience in their particular journey, so that the selection necessary at the start, which offers a broad mixing potential, develops into a personalised array that allows the painter’s singular vision to be seen.

Let’s take a look at a basic palette, based on Le Blon’s Trichromatic System, and then see how this can be adjusted to factor in not only the different hues available, but also the physical characteristics of paints themselves.

Mixing from three cool, single pigment Primary hues gives a broad range of possibilities, and forms a basis for additional colours when forming more specific colour choices.

The first question is: what are the three Primary colours? These change with the colours available at the time. In the 18th Century there were very few to choose from, with the first cool blue, Prussian Blue, discovered (by accident) in 1704. This colour was essential for Le Blon’s system, as the cool hues tend to provide the widest gamut of colours. Today we would use Phthalo Blue instead, as it is brighter so produces clearer colours. Alongside the Blue, a cool, lemon Yellow and a cool, bright Quinacridone Magenta in place of Le Blon’s Carmine, though that is also good.

We can see that these three cool Primary colours produce a broad range of hues. Mixed with each other, they circle the colour wheel with few obvious gaps. Combining a Primary with a Secondary (or Complimentary) colour made from the other two Primaries takes the mix across the colour wheel, through the dark centre, where the combination of all three Primary colours shows the effects of subtractive mixing.

However there are plenty of Primary colours: there are around 20 different Yellow pigments available to artists today, and any of these can replace Lemon Yellow to give you a completely different palette. See what happens when we swap it out for an earthy Yellow Ochre or a warm Chromium Yellow Hue and mix it with the Phthalo Blue. No longer do we have bright leaf Greens, instead the Green shades are muted, softer, not so “loud”. These Yellows may suit a landscape painter better than the original line-up, or a painter wanting quieter tones.

Changing out the Yellow for Yellow Ochre or a Chrome Yellow (left) softens the range of available Green tones, while using a single pigment Orange rather than a mix (middle) preserves brilliance. The limited colour choices of 200 years ago gave way to a flood of new colours in the latter half of the 19th Century (right).

Single pigment colours make the cleanest mixtures. You can find the pigment composition of your paint by looking for the Colour Index: PY followed by a number for Yellow, PO for Orange, PR for Red, and so forth. For instance, Phthalo Blue is made from PB15:3. Colours made from multiple pigments do not mix so cleanly, and combining more than four pigments almost certainly results in mud. When we replace the mixed Orange in the original trichromatic system with a single pigment Orange (PO71 often called Translucent Orange or Poppy Red), the increased brilliance is quite apparent.

Increased brilliance was once shunned. Before the Industrial Revolution ushered in the invention of colours in the middle of the 19th Century, painters had few pigments to choose from, so relied heavily on mixing to create particular hues. They didn’t have access to the colours that we do, such as the wonderful range of Quinacridone Reds (since 1980s), so their palettes were very different from ours. Many colours were eye-wateringly expensive or hard to get (art stores would become a thing after 1850). We can see a transition from Yellow to Red that is very different to our original palette when we use a traditional Yellow Ochre and Vermillion, and though still beautiful it does not possess the range of hues of the modern palette.

The new colours developed in the 19th Century provoked a revolution. Cadmium, Cobalt and Chromium colours were discovered, along with “lake” pigments. Brighter, cheaper and more readily available, painters eagerly took them up, with a group called Impressionists often using them straight from the tube (invented in 1849), unmixed, in a determined show of Modernity. This grew into such brilliant abandon that Henri Matisse and his “Fauves” were called wild beasts!

Many modern pigments are bright, and sometimes that still puts painters off. Phthalo Green is one of these, a bright, glowing emerald that can’t be recreated through any mixture. Brilliant hues are easily tamed though, with their brilliance maintaining a clean result in mixing. Phthalo Green settles into a wide range of tones when mixed with various Yellows to create a broad range of Greens, Blue for turquoise tones, or Reds for silky Blacks and Greys.

The opacity or transparency of a colour is usually indicated by a square on the tube or colour chart, allowing you to choose colours that cover or glaze.

An important consideration in selecting colours is how translucent or opaque they are. This is a characteristic of the pigment (sometimes the binder, as in gouache), which may resemble a slither of coloured glass or a ball of metal, depending on the source material. Translucent or transparent colours are used for glazing, as they let light through them, while opaque colours are used for covering or scumbling (dry brushing). Translucent colours create cleaner mixtures than opaque colours, so including one or more in a mix helps preserve brilliance.

Understanding the inter-relationships of colours – the difference that substituting one Yellow for another, or a warmer Blue for a cooler one, for instance – will begin to shape your palette to your personality. Searching out single pigment colours over premixed hues will improve mixing results, colour harmony and save you money. Soon your colour choices will not only be dictated by the desired result, but the results will be entirely coloured by your choices.

Two-colour mixing examples for the Horadam Ultimate Mixing Set, a collaboration between our very own Evan Woodruffe and Schmincke to showcase the possibilities of less ordinary colours.

We live in a time of abundant colour. No painter before has had so many colours so readily available, and at such relatively affordable prices. We may think a genuine Cobalt Blue is expensive, yet in the 16th Century an ounce of finest Ultramarine pigment cost a month’s salary. Thankfully, Ultramarine was synthesized in 1826, making it much more affordable! So grab a colour chart, try some mixtures (and record them!), and dream of colour.

  You can read more about pigments on our blog:

https://www.gordonharris.co.nz/blog/65-colour-in-the-21st-century-artists-have-never-had-it-so-good-

https://www.gordonharris.co.nz/blog/35-artists-paint-a-closer-look-at-quality

https://www.gordonharris.co.nz/blog/62-green-with-envy

https://www.gordonharris.co.nz/blog/67-here-comes-the-sun

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