There are four colour experiments on display in this room exploring the science behind Turner’s use of colour.

Experiment 1: Colour and Light

a visitor at the Colour and Line Turner's Experiments exhibition

Our eyes distinguish the colour of objects by the wavelength of the light they emit or reflect. We have receptors in our eyes that pick up difference wavelength ranges, which our brain filters, processing them into the experience of colour. A red flower, for example, reflects the red component of the light hitting it and absorbs all the others.

Although there are no clear boundaries between one colour and the next , the ranges marked on the table give a guide to the colour of the light we can see:
red (620-750nm)
orange (590-620nm)
yellow (570-590nm)
green (495-570nm)
blue (450-495nm)
violet (380-450nm)

Experiment 2: Goethe’s Prism

Exhibition view  of the Colour and Line exhibition at Tate Britain

Goethe was the earliest writer to comment on human perception of colour. He noticed that when he looked through a prism, a spectrum of colours became visible around the edges of objects, even those that were black. He created a series of diagrams in his Theory of Colour so that readers could try it for themselves.

Look through the point of the prism. Without moving your head, look to the left and right at the diagram behind the prism. What colours can you see at the edges of the different shapes?

‘The greatest change…is produced by means of prisms, and this is the reason why the experience of colour can be exhibited most powerfully through glasses of this form. Yet we will not, in employing them, suffer ourselves to be dazzled by the splendid appearances they exhibit, but keep the above well-established, simple principles calmly in view.’
Johann Wolfgang von Goethe, Theory of Colours 1810

Experiment 3: Coloured Shadows

a visitor at the Colour and Line Turners Experiments exhibition

Goethe observed that shadows might be coloured, even though they could be thought of as an absence of light. For him, this conflicted with Newton’s idea that all the colours of the spectrum were contained within white light.

With your arm raised above the table, touch the button. Your arm is casting two shadows. Are they different colours?

‘In travelling over the Harz in winter, I happened to descent from the Brocken towards evening: the wide slopes extending above and below me, the heath, every insulated tree and projecting rock, and all masses of both, were covered with snow or hoar frost. The sun was sinnking towards the Oder ponds. During the day, owing to the yellowish hue of the snow, shadows tending to violet had already been observable: these might now be pronounced to be decidedly blue, as the illuminated parts exhibited a yellow deepening to orange.’
Johann Wolfgang von Goethe, Theory of Colours 1810

Experiment 4: After images

Goethe noticed the phenomenon of the after image, where a reverse colour image of something we’ve been looking at appears when we close our eyes. This is most common now when someone takes your photography using a flash. Goethe thought it was particularly interesting that even neutral or non-colours - black, white and grey - did this. He couldn’t reconcile this with Newton’s observations about colour. Newton was measuring how light worked physically, while Goethe was beginning to record how humans perceive colour.

Look into the box beside you. You will see a grey disc - stare at it for a minimum of 10 seconds. Now press the button to turn off the light, but keep looking in the box. After a few moments you should begin to see a coloured image of the disc. What colour is it? Does it change? What about if you close your eyes?

‘I had entered an inn towards evening, and, as a well-favoured girl, with a brilliantly fair complexion, black hair, and a scarlet bodice, came into the room, I looked attentively at her as she stood before me at some distance in half shadow. As she presently afterwards turned away, I saw on the white wall, which was now before me, a black face surrounded with a bright light, while the dress of the perfectly distinct figure appeared of a beautiful sea-green.’
Johann Wolfgang von Goethe, Theory of Colours 1810