Colour Theory and Mixing
Friday 9th January 2026
Peter Keegan is a full time professional artist living and working in Buckinghamshire. He trained at the Cardiff School of Art. He mainly specialises in portraits. He is in the process of publishing a book and has made several Ask an Artist podcasts. He has a variety of painting courses and painting retreats which can be found on his website.
This evening’s Zoom demonstration is on Colour Theory and Mixing and Peter stressed that this applies to any medium. He will be working in oil paint and apart from the fact that watercolorists tend to use the white of the paper rather than white paint, the theory still applies. He will divide the evening into two parts.
Part 1- Theory : How to mix colour accurately.
Part 2 – How we see colour. How it can be bent and shaped.
Most artists will recognise the colour wheel although not everyone uses it however it is very useful to understand colour and how to mix it. The colour wheel is firstly made up of the Primary colours of Red, Yellow and Blue. The Secondary colours are Green, Orange and Purple. The colour wheel provides the full colour spectrum and it divides into cool colours on one side and warm colours on the other. Warm colours will contain red while blue combines to make cool colours.
Tonal value refers to how light or dark a colour is. Every colour has a grey scale. To lighten a colour add white while black will darken the tone. White is the coldest colour in the palette. Ice White appropriately describes the coldest colour available.
Complimentary colours are found on the opposite side of the colour wheel. Green is opposite Red, (think Christmas) Orange is opposite Blue (think sports), Yellow is opposite Purple and tends to be associated with luxury especially when the yellow is gold (think Cadburys).
Analogous colours are groups of colours that are found next to each other on the colour wheel. In the chart above the analogous colours all contain an element of the Primary colour Blue. They create harmony and go well together.
Tertiary colours are colours made with one Primary colour and only one colour that is next to it on the colour wheel. Examples of tertiary colours are turquoise, teal, pink, rose, magenta, chartreuse or lime green
Tonal Values refer to how light or dark a colour is. The tonal scale is Yellow, Orange, Green, Red, Blue and Purple. Colours change their temperature depending on their environment and what they are compared with.
After discussing the basis of the colour wheel Peter turned to colour mixing. He had prepared a palette of four paints: Titanium White; Bright Yellow Lake; Scarlet Lake; and Ultra Marine Blue. He then took four different colour swatches to demonstrate how the colour on these swatches can be matched with paint.
The first swatch was called “Spontaneous Combustion”. It was clearly not the same colour as the red paint on the palette but starting with the nearest colour to the one desired, Peter began with red paint, then he added some blue but he could see the desired colour was slightly chalkier so he added a little white. He then painted on the card to show that he had indeed matched the colour with his paints.
The next colour swatch was called “Blue Batik” so he began with the Ultra Marine Blue. This needed to be lightened with white and then made more purple with a little red. It took six mixes to reach the right match.
The third swatch was called “Hunting Jacket Green”. Green is a secondary colour made with yellow and blue. It will take more mixing to attain a match with this colour as can be seen in the image below. Nonetheless, Peter was only using the four paints he had on his palette to reach the match.
Finally, Peter took a grey swatch with the unlikely name “Poetry in Motion”. This was the lightest swatch so far. Consequently, Peter started with white, added a little red creating a pink. He increased the saturation of the hue with colour and desaturates it with white. Peter reminded people that what he was seeing in the studio and what we were seeing on line might vary slightly but after 15 mixes he had achieved a good match.
Next Peter took an apple to try to get the colours of the fruit bang on using the colours in his palette. Hue, which is often referred to as chroma by Americans, is the colour which can be saturated to increase the tone or desaturated with white. Peter saw the contour as yellow so he began with yellow and mixed in the red. He then used a little blue to darken the darkest side of the fruit. .
Looking at the core and the stalk Peter used a little green and yellow for the centre and the three primary colours to produce the dark brown of the core. The highlights come last and he used a combination of yellow and white, not pure white.
Part 2 – How we see colour
Colour Harmony is where groups of colours come together to great effect. Peter put up some well known artists’ paintings to illustrate this. The first was Claude Monet’s Houses of Parliament which uses an analogous palette of blues and purples but he pointed out the use of the yellowy orange, which are the complimentary colours to the blues and purples.
Peter then put up this David Hockney painting which uses intensity of colour with the high contrast of red earth and green fields.
Everyone would recognise Van Gogh’s Sunflowers which has a limited palette of yellows.
People were hesitant to name the artist of this painting in very muted desaturated colours using a tertiary colour palette and may have been surprised to learn that it was also a David Hockney painting.
Buckingham Landscape
Peter explained that he was going to use a reference photo of a Buckingham landscape to further demonstrate how colour can be manipulated to produce very different effects with 10 mins per sketch.
The first one would be an accurate representation and in fact he changed the blue in his palette from Ultra Marine Blue to Cobalt Blue to better depict the sky colour.
Next he painted an analogous/tertiary sketch with colours that all go with each other. The purples are harmonious and create a different feel to the scene. All the colours go with each other and are harmonious.
For the third little sketch ‘think Hockney’. He will use high saturation to intensify the colours. Contemporary artists often take sharp contrasting colour to make them bounce across the scene. (LFauve artists and Kaninsky)
Finally, it was de-saturation. It was to be almost completely devoid of colour. It necessitates the use of a lot of white. (Mogdigliani and Gwen John).
Below is the set of four little sketches
Colour is the most emotive thing available to us as artists. Subtle colour changes can change the emotional impact of the painting. Art with a capital A is trying to say something. You should write down the feeling that you want to convey so that you do not get lost. The emotive side comes from colour. It gives the artist a wider vocabulary.
To avoid muddy colours check the labelling on a tube of paint. The more pigments in a paint the muddier it is likely to be. Paynes Grey is made up of three pigments. Sap Green has lots of different pigments. Check what is written on the tube.
Series numbers indicate the price and pigment quality. Series numbers run from 1 – 6 or 7. For instance, Chinese Vermilion is series 7 and might cost as much as £80. A code such as PB29 indicates the name of the pigment i.e Ultra Marine Blue. Organic or Inorganic, Transparent or Opaque. Light Fastness and Tinting Strength. Artist Quality paints give stronger hues.
Peter advised artists to use a large palette. He sees his colours as personalities. Some colours get on especially well with each other. He uses this enormous palette with warm colours on the left and cold colours on the right. He keeps the white and black paint far apart from each other.
Finally, Peter illustrated how slippery colour can be and of course there are some people who are actually colour blind. Colour blindness is more often found in men. The test card below can help determine whether someone is colour blind by whether they can see the numbers in the circles. If you are not colour blind the numbers read 6,12, 29 and 74.
To illustrate just how the mind can play tricks on interpreting what it sees Peter illustrated with a number of images where despite appearances objects are in fact the same colour. For instance in the images below Tile A and B are the same colour, the pink crosses are the same colour and so are the peacocks. The backgrounds create the illusion that they are different.
This can of Coke image is particularly unbelievable. The colour red does not exist in this image and yet everyone sees a red Coke can. This might be societal. Perhaps people who have never seen one before might not be fooled as easily.
Peter Keegan runs a wide variety of classes and courses that can be found on his website as well as four classes on Colour Theory on line. For further information please see:
Grateful thanks go to Peter Keegan for an excellent demonstration of colour theory and mixing. Several members have already written to say what an extremely fascinating and informative demonstration this was. No knowledge was assumed and the whole topic was covered and illustrated very effectively.
Write Up by Carole Head