How many times did you mix your primary colours in the hope to get the imagined brilliant orange or the perfect purple but instead you get only muddy colours?
Since school time we are taught that the primary colours are red, yellow, blue and that from mixing these colours we can obtain all other colours. But the more I used only this three colours, the more I disappointed and became aware that this was a very limited palette and that it didn’t give me the expected results. For example taken the colour Purple (blue + red), it didn’t matter what red or blue I used. I have never managed to create a beautiful purple but only a muddy tone.
Then I did some research to explore the way colours work and here is what I discovered.
A Little History About the Development of the Colour Theory
The first colour wheel was discovered by Isaac Newton in the 18th century when during an experiment he observed that the light could be divided into 7 base colours (red, orange, yellow, green, blue, violet, indigo) and assumed that from the union of all colours together we could return to the white.
In the following years this assumption turned up to be inexact and it was Goethe with his work “Die Farbenlehre” the one who eliminated the colour indigo and reorganized the remaining 6 colours according to a complementary principle. Complementary colours are couple of colours where the first colour is a primary colour and the second one is the result of the union of the other 2 primary colours. These colours become brighter if put next to each other. Examples for them are yellow and violet, blue and orange blue, red and green. The colour wheel by Goethe it is considered as the starting point for the development of the modern colour theory.
Additive vs Subtractive Colour Mixing Models
When we talk about colour mixing systems it is very important to analyse how secondary colours are obtained.
Additive Colour Mixing Model
In this case the secondary colours are created by overlaying two or more wavelengths of primary colours (as it happens in the human eyes). An example of this kind of mixing system is the RGB, which is basically how our eyes work and the one used in TV-screens.
Subtractive Colour Mixing Model
In this case the secondary colours are created by overlaying two or more wavelengths of primary colours so that each colour involved in the mixture absorb a particular wavelength and the secondary colour is based on the remaining wavelength. Examples of this kind of mixing system are the traditional RYB and the CMY(K), used in the printing industry, or the way in which paint mixing works.
In the following paragraph I will talk more in detail about the different colour mixing models RYB, RGB and CMY(K).
Colour Mixing Models: RYB vs. RGB vs. CMY(K)
Basically a colour system (or colour model) is a 3 dimensional space where each dimension is represented by a primary colour and the secondary colours are each colours found in this space and generated by the combination of two or three of these primary colours.
The most known colour systems are the RGB, the RYB and the CYM(K) Colour Systems.
RGB Colour Mixing Model (also called Light Model)
The RGB Colour Model is the one which is primarily used for TV-screens and is based on the way in which our eyes, through different receptors called “cones”, perceive the white light as a combination of three wavelengths (red, green, blue). When the light stimulates two or more of these cones according to the frequencies, our eyes will unite this frequencies into one single frequency and give back the secondary colour corresponding to that resulting frequency. For this reason the primary colours of the RGB (red, green and blue) are also called additive primary colours of light.
The secondary colours of light and the entire colour range, which are produced by the union of two or more frequencies of the primary colours at different intensities, are:
yellow (red+green),
cyan (blue+green),
magenta (red+blue).
The sum of all primary colours gives back white; the complete absence of them gives back black.
The complementary colours of light in a RGB Colour Model are:
Red - Cyan
Green - Magenta
Blue - Yellow
RYB Colour Mixing Model
Whilst the RGB Colour Model is an additive colour system, the RYB Colour Model is one of the subtractive colour models. It is the traditional one taught since we are kids and the starting point for the colour wheel by Itten.
In the RYB colour model the primary colours are Red (R), Yellow (Y) and Blue (B) and the secondary colours are obtained by intermixing them.
The secondary colours in this system are:
Green (Yellow+Blue)
Purple (Red+Blue)
Orange (Yellow+Red)
The sum of all primary colours gives back black; the complete absence of them gives back white.
The complementary colours in a RYB Colour Model are:
Yellow - Purple
Blue - Orange
Red - Green
CMY(K) Colour Mixing Model
Whilst the RGB Colour Model is an additive colour system, the CMY(K) Colour Model is the other subtractive colour model and is primarily used for printing devices.
In the CMY(K) the primary colours are Cyan (C), Magenta (M), Yellow (Y) and, in the printing industry, they are completed by Black (that is indicated with the letter K for Key). The secondary colours are obtained by exploiting the way at which pigments absorb the different wavelengths when they are intermixed.
For example if we mix yellow (perceived as the sum of red and green) and magenta (perceived as the sum of red and blue) the resulting mixed colour will be red because:
The green contained in yellow will be absorbed by its complementary magenta and neutralized. What will remain in the yellow is the red;
Similarly the blue contained in the magenta will be absorbed by its complementary yellow and neutralized. Also in this case what will remain in the magenta is the red.
The secondary colours in this system are:
Bright Green (Yellow+Cyan)
Bright Orange (Yellow+Magenta)
Bright Purple (Cyan+Magenta)
The sum of all primary colours gives back black; the complete absence of them gives back white.
The complementary colours in a CMY Colour Model are:
Yellow - Bright Violet
Cyan - Bright Orange
Magenta - Bright Green
RYB, RGB and CMY(K) Colour Mixing Models for Acrylic Paints
Apart from RGB Colour System, which can be applied when using interference paints, I decided to focus on the differences between the standard (RYB) and the CYM(K) because acrylic painting (which is pigment based) is basically a subtractive mixing model.
However, over time I have learned that the RYB system alone is not enough to cover all the possibilities of the colour palette, even though it is important as a starting point. With this system you can achieve dark and sometimes murky colours, no matter what blue or red you use.
CMY(K)-Model, on the contrary, is very good if you want brighter colours. I made some tests and substituted the red with the magenta and the blue with the cyan (through a turquoise paint) and got following results:
According to the shade of red, blue, yellow that you use, you can get different shades of orange, green or purples or completely unexpected colours. In this case you have also to keep in mind the so-called tinting strength of your colours. Tinting strength means that in a mixture one colour dominates the other one (for example red over yellow). In that case the mixture will tend to the hue of the dominating colour and you will need to use a bigger quantity of the other to go in the opposite direction (for example 1 part of red and 3 (or more) parts of yellow to have a yellowish orange). To know more about it, watch the tutorial Quick Tip 290 – Color Strenght by Dianne Mize “In The Studio Art Instruction”
When substituting red with magenta you can get more pinkly oranges or more purplish tones
When substituting blue with turquoise you can get brighter purples
When you use red you can get bright oranges or darker und muddier purples.
After this experiment what I understand was
there are more alternatives for primary colours according to our needs and that we can get more variations of purple, orange and green by substituting one or two of the classical primary colours.
both RYB and CYM Colour system are complementary to each other and not substitute.
I hope I could inspire you to experiment and find new colours on your own. Let me know in the comments below.
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Have a colourful and creative day!
Laura