colour update

I know, I know, I said there’d be a weaving update, but this is very nearly almost weaving.

When I first posted about the “serious” colour scheme, I linked to this useful summary of Goethe’s colour triangle and illustrated the mixing of primary and complementary colours. Then I borrowed a couple of books on colour from the university library, including the very readable Colour by Paul Zelanski and Mary Pat Fisher. This book gives an overview of all the different aspects of colour, including physics, physiology and the practical aspects of working with colour, so they don’t go into depth on any particular theories. However, they illustrate Goethe’s triangle and comment that

Goethe offered an alternative model in which the primaries … were the corners of a triangle, the secondaries the sides, and tertiaries the mixtures of the three surrounding colours.

The three surrounding colours? I did a double take when I read this, as I had understood from the colour class — and from those notes — that the tertiary colours were made by mixing a primary and its complementary colour. Then I had a think: after all, there are only three primaries and in either case they are all represented in the mix.

Imagine that we want to colour in the triangle marked T in this picture and suppose that each secondary colour is a 50-50 mix of the two neighbouring primaries.

If we mix red and green with “the primary dominating the mixture”, as originally proposed, then we have a certain amount of red and a smaller amount of green, which is actually half that smaller amount of blue plus half the amount of yellow. I find it easier to think of these things in symbols rather than words, so I would write

T = a x Red + b x Green

and then break it down into

T = a x Red + b x 0.5 x Blue + b x 0.5 x Yellow

where a is the amount of red which allows it to dominate the mixture and b is the smaller amount of green.

The new information doesn’t tell me what proportions of the “three surrounding colours” I should use, so I shall assume that I mix them equally. This gives me

T = Red + Violet + Orange

which I can break down into primaries

T = Red + (0.5 x Red + 0.5 x Blue) + (0.5 x Red + 0.5 x Yellow)

But then I can add up all my little bits of red and I have

T = 2 x Red + 0.5 x Blue + 0.5 x Yellow

This, thank goodness, looks very similar to my mix of red and green above: I just need to substitute a = 2 and b = 1, which does indeed give dominance to the red over the green.

From this little exercise I am satisfied that the two descriptions are most likely telling me the same thing and it is safe to go back to the loom.

colour update” was posted by Cally on 18 Sept 2010 at

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2 Responses

  1. Evelyn Oldroyd
    | Reply

    Now I will have to find my old art school notes to see what they say about Tertiary colours.

  2. Cally
    | Reply

    I did some scouting around and found two distinct types of definition for tertiary colours. One kind of definition says that they include all three primaries (as in this case); the other kind is talking about the modern colour wheel and the mixing of a primary with an adjacent secondary so that you get, e.g. a red-orange rather than a “straight” 50-50 orange. That’s the definition I have been accustomed to, but it appears to be using recycled terminology!! I’d love to know what you learned at art school.

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