A Guide to Mixing Colour

Posted by Sarah Jane Humphrey on

In our recent blog post ‘An Introduction to Colour Theory’, we explored colour theory, primary, secondary and complementary colours, and how complementary colours react together once combined. This helped us understand that, although colour mixing can be a tricky affair, there’s a certain science behind it, which can be learnt and used with consistency. 

Here, we explore the history behind colour strategy, and offer some more of our tried and tested tips and tricks, to help explain how you can add life and light into your paintings.  


Applying Colour

Johannes Itten, through his research and association with the Bauhaus School, went on to develop 7 colour strategies which have changed the way in which we can observe and apply colours. Understanding how certain colours, through their contrast or hue, work with or against each other can have a measurable effect on your finished artwork. Colours applied in the incorrect manner will look garish and unnatural and will not achieve the results you intend. 

A good tip is to make yourself a colour wheel and take time to experiment with mixing colours and variants of tones. Then, when working on future studies, don’t be afraid to return to these if you get in a pickle. 

Greens in particular can be very difficult to get correct, so are a good starting place for any experiments. By mixing very small amounts of another colour with green and gradually increasing the volume of added mixture each time, you can create a visible measure of variations. Record notes by the side of your experiments so you can recall the colours needed at a later date.


Colour swatches showing how different greens can be mixed

Green Palette


Warm and Cool Colours

Over time and with experience you will gain an eye to pick out different tones to colours, and mix them to your benefit when painting or drawing. Warm colours are those that lie at the red and orange end of the spectrum. When we observe these they tend to ‘advance’. This is due to the properties of those colours when we revert back to viewing them as spectrums of light. Each spectral colour is actually defined by the wavelength of its light: the warmer colours obtaining a higher value than the cooler and therefore standing out or advancing more. The cooler, more 'blue-ish' colours at the opposite end of the spectrum, have a lesser wavelength of light and will appear to ‘recede’.

By incorporating these observations made by Sir Isaac Newton we can then begin using warmer or cooler variants of colour to make areas really pop out from an artwork, or others retreat back. Used in conjunction with accurate drawing from perspective and effective use of reflective light and shadow contrasting, your artworks will take on a stunning realism.

 Botanical painting, green grapes on vine

 Botanical Painting

Colours to achieve shadow

This will be down to your personal preference. Much like any use of colour, all artists tilt towards preferred colours. One example where this can be seen is in the rise of impressionism, a fabulous movement of colour and mark making investigations. Although a far cry from the realism scientific illustrators are trying to represent, the impressionist’s observations of the light reflected onto different surfaces is certainly one to take note of. Look at the way light and sky colourations fall onto snow, sometimes giving it an almost violet hue. Or vibrant flowers reflecting onto the shiny surface of leaves. Colours less obvious to the mind, very often appear once we look at subjects in closer detail. The smart use of dark reds in the shadow of greens, not only gives a harmonious collaboration of colours but also a more natural look than darkening a pigment green with black.

Experiment with colour mixing, and don’t be afraid if the separate paints or pencils look a real clash in their pure pigments before mixing. A good rule of thumb with botanical and scientific illustration is to apply colour cautiously, gently increasing the mixtures of paint quantities or deepness of coloured layers in the use of pencil crayon. It may sound a little faffy but to get into the regular practice of gently wiping your brush to remove the excess paint on a piece of scrap paper each time before painting onto your artwork will save you making any new unwanted marks. Many artists will tell you never to use the colour black. Although a true black is unlikely to crop up in naturally derived subjects, it is if used in a very delicate manner the real making of bringing a subject to life.

 A cool colour palette and using deeper tones, darker grapes on vine

A cool colour palette and using deeper tones


Greys, browns, deep purples, violets, indigos, dark reds and greens all make excellent colours for deepening shadowed areas. Gradually adding them into your artwork creates subtle colour changes. Alternatively, ‘paynes grey’ is a favoured colour of many artists and a great alternative to black, to use at some (but not all) of the darkest points of shadow. It will give you almost every depth of shadow you will need to make. You can use a little ‘payne’s grey’ mixed in with your darkest colour (for example with ‘burnt umber’), to achieve a really deep result. If there is an area of complicated darkness, for example a bushy plant like lavender or a root ball of some sort, you may need to darken still to command a true sense of contrast within your artwork. Being bold with contrast will offer you as the artist a fabulous depth and realism, much in the same way as using very definite areas of reflected light and daring to go quite light in areas.


A Final Top Tip

It's a good idea to paint with caution when using a larger selection of colours to create a realistic artwork that your palette doesn’t become muddied. To clarify this as a term, ‘muddied’ is when the wrong colours have been mixed together and cause a dull tone. The loss of vibrancy across a painting from this can look lifeless, and when using water soluble paints can often be tricky to rectify. To avoid this, try not to become lazy with cleaning your palette or adding new paint to already mixed muddy colours. You really are best to begin again with a clean area in your palette or if that is not possible to wash it out and start again.

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