Why can’t I mix the right colour?
Imagine a time of poster paints and sugar paper. Of bright colours, chubbie crayons, green grass and blue skies. These were perfect painting days apart from one thing I almost forgot to mention….brown sludge.
Lots and lots of brown.
Your teachers told you ‘mix yellow and blue to make green’, red and blue to make purple.
You listened, but the problem was still there.. you created brown sludge.
What were you doing wrong?
Nothing, you were just given the wrong paints…
The hidden secret in paints
The way paint looks when it comes straight out of the tube is usually very different to how it reacts when you start painting with it. This is especially true with darker colours, the lighter colours such as yellow often behave much as you would expect, hence why a yellow sun always worked at school.
So the primary colours red, blue and yellow alone are not the whole story. Small amounts of other colours are hidden within each pigment – this gives each colour a colour bias.
Colour theory is misleading
The colour mixing wheel is a great tool, it is handy to have one in your studio for quick reference.
Remembering all the complementary colours when you are starting painting can be tricky.
However, if you take the theory at face value you are in for hours of frustration when trying to mix the colour you want.
What is colour bias?
Every single colour has a bias towards another colour.
A blue pigment will have either a red bias or a green bias in comparison to another blue pigment.
Colour ‘theory’ states that you can mix all 3 secondary colours with the 3 primaries,
However, this will only work if a ‘pure’ primary colour is used.
With paint pigments, you can’t find a ‘pure’ red, for example, that will make both a good orange (when mixed with yellow) and a good purple (when mixed with blue).
This is because the red will have a bias towards either orange or purple due to the chemical impurities found within every pigment. (see What are my Acrylic paints made from?)
So a red that has an orange bias (Cadmium Red) will mix a bright orange, but will not mix a bright purple.
Blue & Yellow don’t make Green
You mixed the correct colours, a blue and a yellow, but the finished colour is a dull, murky green. Not the vibrant colour you had envisaged.
So what do you do?
Add more yellow? It gets a bit lighter but is still wrong, what about more blue? no, now it’s too dark…what it needs is brightening up, so you reach for the white paint, only to find this doesn’t work either you’re left now with a grey looking green.
Disheartened, you make another trip to the art shop to buy a pre-mixed bright green.
Why didn’t the colours mix to the colour I wanted?
How to mix a bright green
The greenest or cleanest green is made by using a green shade blue and a green shade yellow. (check out the video above at 1 min 12 sec)
- Ultramarine blue has a red (warm) bias so would be the wrong choice for vibrant green.
- Phthalo blue has a green (cool) bias so this would be a good choice for a bright green.
- Cadmium Yellow has a red (warm) bias so would be the wrong choice for vibrant green.
- Hansa yellow has a green (cool) bias so this would be a good choice for a bright green.
Option 1: Ultramarine blue + Cadmium Yellow light = muted green
Colour Bias (purple-blue) + (orange-yellow)
Option 2: Phthalo Blue + Hansa Yellow medium = bright green
Colour Bias (green-blue) + (green-yellow)
If we look at the colour bias on Option 1 we are essentially mixing 2 complementary colours blue and orange together.
Complimentary colours are those that lie opposite each other on the colour wheel and will mute each other out, making it impossible to make a bright clear colour.
Option 3: Cerulean blue + Hansa yellow = very bright green
So in Option 3 we have a yellow that has a large amount of yellow and small amount of green. Mixed with a blue such as Cerulean blue, which has a large amount of blue and a small amount of green resulting in a very bright green.
- large amount of yellow
- Small amount of green
- Very Tiny amount of orange
- Large amount of blue
- Small amount of green
- Very tiny amount of purple
The secret to effective colour mixing is understanding the different pigment qualities of paints so you can match the colour you want every time.
For a more intensive look at colour bias, I recommend you have a look at Blue and Yellow Don’t Make Green by Micheal Wilcox.
It gets a tad scientific and can be a bit overwhelming to start with but if you paint with watercolours has a huge selection of samples of different colour mixtures you can make.
You might also like my Simple Colour Mixing Course that introduces the basic of colour mixing with acrylics and classical painting techniques.