Splash of Colour

Colour is the range of visible light. Colour can be seen when light strikes an object. The light is then reflected into the human eye, from there a message is sent to the brain and the information is processed and interpreted – telling us what colour we see.

Colour can be broken down into three parts:

hue, which is colour in its purest form;
intensity, which is the vividness of a colour;
tone or value, which relates to light or darkness of a colour.

Different values are created by tints and shades. A tint is created when white is added to a colour, while a shade is created when black is added to a colour.

The Colour Wheel, which was invented by Sir Isaac Newton (1642–1726), is made up of three types of colours:

Primary: red, yellow and blue. No two colours can be used to make these colours; they are created through the use of pigments.
Secondary: orange, green and purple. These colours are made by mixing two primary colours together.
Tertiary: red-purple, red-orange, blue-green, yellow-green, blue-purple and yellow-orange. These are made by mixing a secondary and a primary colour together.

Some colours are known as ‘warm’ colours and some colours are ‘cool’. Which colours would be cool? What do these colours remind you of?

Complementary colours are those opposite each other on the colour wheel.
Harmonious or (analogous) colours are next to each other on the colour wheel.
A monochromatic colour palette consists of variations (tints and shades) of one colour.

Seeing and Perceiving Colour

Colour and light are inseparable. Two scientists working in the field of chemistry and physics, Sir Isaac Newton (1642–1726) and Michel Eugéne Chevreul (1786–1889) were instrumental in helping us understand the way we see and perceive colour. Newton analyzed the nature of light, and chemist Chevreul analyzed the visual effects of colour juxtapositions. Chevreul determined that when the eye sees two colours side by side, they appear vastly different in colour and strength.

What is light?

Physics is a strand of science that helps us to understand the properties of matter and energy, such as heat, sound and light. Light is all around us and is made up of waves with varying wavelengths. These different wavelengths are perceived by our brain as different colours. The part that we can see is the visible spectrum (familiar to us as the colours of the rainbow), which was discovered by Sir Isaac Newton, author of Opticks. Wavelengths are perceived by our brain as different colours. Most objects that we see in everyday life reflect a range of wavelengths of light to the back of your eye at different intensities.

Stanislaus Ostoja-Kotkowski, born Golub, Poland 1922, died Adelaide 1994, *Projected laser beam*, c.1976, Adelaide, direct positive colour photograph, 35.2 x 27.7 cm (image); Gift of Edward and Jane Booth 2003, Art Gallery of South Australia, Adelaide, Estate of J.S. Ostoja-Kotkowski.

The human eye plays a very important role in how we see colour. It consists of many components including, but not limited to, the cornea, pupil, iris, lens and retina. The retina contains approximately 126 million light-sensitive cells, which can be categorised into two types of cell, rods or cones. Rods help us see in grey scale, particularly in low light conditions such as night time. Cones allow us to see colour. In humans, each cone can contain one of three types of photopsins (photoreceptors), which are pigments sensitive to either a red, blue or green wavelength of light.

The wavelengths of light reflected towards the eye stimulate different combinations of these pigments, enabling us to see a variety of colours (not only red, blue and green). Stimulation of different combinations of the pigments enables us to perceive millions of different colours. For example, the perception of different shades of purple is due to varying combinations of red and blue cone cells being stimulated. Yellow light (which has a wavelength between that of red and green light) stimulates the red and green cones and this information is decoded by the brain to give the perception of yellow light.

Paul Signac, born Paris 1863, died Paris 1935, *Saint Tropez: the port*, 1897-98, Paris, colour lithograph on paper, 43.3 x 32.7 cm (image), 52.0 x 39.9 cm (sheet); South Australian Government Grant 1980, Art Gallery of South Australia, Adelaide.

The mosaic-like surfaces of paintings by the Neo-Impressionists play on the function of the retina’s cone cells. The brain attempts to make sense of the pixelated field of colour, which consists of small strokes or marks of contrasting coloured paint placed next to each other, giving the work a shimmering, luminous quality and thus dazzling the retina. This can be seen in Prairie à Éragny, 1886, by Camille Pissarro. Neo-Impressionist artists were interested in colour division, that is, in placing both contrasting and complementary colours (colours opposite on the colour wheel) side by side. This approach is based on Michel Eugéne Chevreul’s Laws of Simultaneous Colour.. Paul Signac’s use of this technique, combined with pure colour and rhythmic lines, enabled him to also create the illusion of movement. The boundaries between the complementary colours used in Red Buoy, 1895, and Saint Tropez: the port, 1897–98, create an intense colour effect making his works of art luminous and bright.

Rainbows, colours, prisms and wavelengths

The light we see, both natural and artificial, is made up of all the colours of the rainbow. These separate colours can be viewed if the white light moves from the air into a different medium, such as water or glass, at an angle. In both of these cases, the wavelengths of light slow down and bend. The different colour wavelengths slow down to different extents which makes them bend differently, separating the colours. When this occurs in moisture in the atmosphere, we see rainbows in the sky! We can also manipulate light by passing it into a glass prism at an angle to see the same effect. A good explanation can be found on ABC Education, ‘How do Prisms create rainbows?

Hear from Dr Lisa Slade as she discusses how and why artists use colour.

Investigate the work of Stanislaus Ostoja Kotkowski and his use of light, colur and movement.
When do we see rainbows in nature? Draw a diagram that shows how rainbows appear in nature.
Locate works of art in the collection that capture different times of the day. As a class discuss the qualities of the works that suggest to you what time of the day it is.
Look for works of art that where artists have used Chevreul’s theory of colour juxtaposition. What do you notice about the relationship between the colours that sit side by side?

Stanislaus Ostoja-Kotkowski, born Golub, Poland 1922, died Adelaide 1994, *Laser light composition*, c.1982-84, Adelaide, direct positive colour photograph, 25.4 x 30.4 cm (image & sheet); Gift of Edward and Jane Booth 2003, Art Gallery of South Australia, Adelaide, Estate of J.S. Ostoja-Kotkowski.

Investigate the meaning of colours. How have these meanings changed over time and what do they signify in different cultures? Did you discover any colours with multiple representations? For example, the colour red is often associated with love AND anger. What other meanings can you find for the colour red? Research other artists throughout time who have predominantly used red, or another singular colour, in their works.

In the middle of the twentieth century, the colour field painters emerged in Britain, Europe, the United States and Australia. These artists did not depict recognisable subjects; instead colour was the main subject of a work of art, in which stripes, targets and simple geometric patterns were painted. Create a collage with coloured paper that is inspired by mathematics and the colour field painters.

Set up the prism experiment in your classroom. Shine a light (i.e. torch) at the prism on an angle and view the effect on a screen (a white piece of paper). Investigate what happens as you move the prism. TIP: See The Tinkering Studio video in resource list.

If you have access to a convex lens, try positioning the lens to bring the separated colours back together. Where would you position the lens? Photograph your observations during the prism experiment. Using these images as references, create an impression of what you witnessed using collage or watercolour paints.

Seeing Colour

Humans can only see a very narrow band of colours – red, orange, yellow, green, blue and purple. There are colours that run through the Ultraviolet (UV) and Infrared spectrum, above and below the colours humans can see. The section that humans can see (from 400nm to 700nm) is highlighted on the Electromagnetic Spectrum diagram. UV radiation is outside of this spectrum, but you can get UV decorations such as stars for bedroom ceilings or special effects makeup and body paint, that only shows up under UV light. These items contain chemicals that absorb UV light, and re- emit the energy as visible light. Most humans cannot see the UV light emitted by the light, but can see the re-emitted visible wavelengths. Some animals can see in the other spectrums. For example, spiders and a lot of insects, including giant centipedes, can see in the Ultraviolet range.

In any species random variations in genetic makeup occur during reproduction, which result in different characteristics. Within the human species there is genetic diversity, which results in some people having different characteristics, like eye colour. Some people have genetic differences that affect the cones in their eyes, and hence some people see very little colour and some people can see beyond the visible spectrum into the UV and infrared wavelengths. In many psychological experiments, it has been shown that people perceive colours differently. A person’s mood has an impact on how shades of colours are perceived. The brain tries to interpret what it is seeing, using previous experiences.

Light entering the eye is the first stage of seeing. The brain must process the information and make a decision as to what information it wishes to prioritise. This results in people perceiving colours and images differently. The brain interprets colours using contrast, hence colours look different to us depending on the surrounding colours. TIP: Look at Banyon Wall by Sydney Ball and Seris 33, orange and magenta added to green and violet in two colour twist by Bridget Riley.

Bridget Riley, 1931, *Coloured greys*, 1972, London, colour screenprint on paper, 70.0 x 70.0 cm (image), 72.5 x 72.5 cm (sheet); South Australian Government Grant 1973, Art Gallery of South Australia, Adelaide.

Responding
Making

Sometimes our brains are ‘tricked’ into seeing different colours, these are optical illusions caused by the mixed messages that our brain receives. What colours do you see in Bridget Riley’s work? Using the scientific principles of how we see colour, explain how Riley has created an optical illusion.

Introduced species of plants and flowers were one of the many inspirations for the French Impressionists. Investigate one of these species and discuss the pros and cons for introducing foreign plants and flowers.

Imagine if people could see into UV and infrared wavelengths and suggest any evolutionary advantages. Although some people can see slightly into seeing other spectrums, most humans haven’t adapted to this (yet!). Why do you think this is? Suggest how in the future we may evolve and adapt to seeing in other spectrums.

Why do some animals or insects have the ability to see in different spectrums? TIP: Consider what they eat, and what colours those things are. Perhaps look at scorpions as a starting point.

After investigating other moments in art history where artists have explored colour, make your own work of art that responds to the science of colour. You might like to consider optical illusions or investigate contemporary 4D practices.