How to Mix Colours When Painting in Acrylics

Why I like to mix my own colours

There are hundreds of different paint colours to choose from when you visit the art store. If you are like me, they all look so inviting you want to buy them all. However, you probably don’t want to buy a separate tube for every colour in your paintings. Mixing colours will save a lot of money and give you a greater range of colours to choose from. Read on to find out how I choose which colours to use for mixing.

Why you need more than one red, one yellow and one blue to mix the perfect colour

Some people will tell you that to mix any colour need only one red, yellow and blue, the primary colours.  Technically, this is true, but that is not quite the way it works when it comes to painting.  Here’s why.

Artists’ paints, or any paint for that matter, are not true primary colours.  

True primary colours are the refraction of light, like the rainbow. Paint companies use pigments to imitate primary colours, but they are never truly pure. Instead, red, yellow and blue paints will always lean a little towards one of the other primary colours.

You will notice that artists’ paints usually have different varieties of each primary colour.  Some reds, for example, lean towards crimson while some have more orange tones. These differences are commonly referred to as warm and cool hues. A warm and cool hue of each primary colour is what you will need to mix any colour. Additionally, white is used to lighten the colours. For ease of colour mixing, I also think it is worth adding at least one green to your painting kit.

Paint companies often have fancy names for the different hues of each primary colour. Often, the name is based on the source ingredients of the pigment. Cobalt Blue, Cadmium Red and Yellow Ochre are all good examples. In the next section, I explain how to know which colours are warm and which are cool. I will also let you know why warm and cool hues make a difference when it comes to mixing paint colours.

Warm and Cool Colours

The way I like to think of warm and cool colours is that warm colours are like the sun.  They are reds, oranges and yellows.  Cool colours are like the ocean, greens and blues. 

When it comes to buying paints, you will be confronted with a whole range of blues, yellows, reds and greens. Each one of these colours can be categorised as warm or cool.  Ultramarine blue, for example, is considered a warm blue. Although blue is a cool colour, Ultramarine contains a bit of red, which is a warm colour. 

On the other hand, Pthalo blue is considered a cool blue because it contains a little bit of green. In the case of red, Alizarin Crimson is a cool red because it contains a bit of blue, a cool colour.  Burnt Sienna is a warm red because it contains a little bit of yellow, a warm colour.

This concept is simple enough to remember when you are using paint straight from the tube, but things can get a little muddy when you start to mix your own colours.

It becomes a bit clearer when you take a look at the colour wheel.

The Colour Wheel

Here is a colour wheel chart I created.  You can download a copy to keep by clicking on the image.

Primary Colours

These are the three primary colours spaced evenly around the wheel.  They are:

• red (warm)
• yellow (warm)
• blue (cool)

Secondary colours

When you mix any one primary colour with any one of the others, you create a secondary colour. Secondary colours fit in between each primary colour on the colour wheel:

• orange (red and yellow)
• green (yellow and blue)
• purple (red and blue)

Tertiary Colours

When you mix a secondary colour with one of the primary colours it already contains, you create a tertiary colour.  These sit between the secondary and primary colours on the colour wheel.  Examples of tertiary colours are:

• turquoise (blue and green) or [blue + (blue+yellow)]
• violet (purple and blue) or [blue + (blue and red)]
• lime green (green and yellow) or [yellow + (yellow+blue)]

A tertiary colour can also be described as a warm or cool version of its nearest primary colour. For example, any hue between:

• yellow and orange is warm yellow
• orange and red is warm red
• red and purple is cool red
• purple and blue is warm blue
• blue and green is cool blue
• green and yellow is cool yellow

Complementary colours

Complementary colours are those that are opposites on the colour wheel.  Each secondary colour is complementary to the only primary colour that is not contained within it. For example, Blue is opposite on the colour wheel to Orange (a mix of Red and Yellow). When you mix complementary colours, all three primaries are present. The result is a neutral colour, either:

• black
• brown
• grey

Understanding warm, cool and complementary colours is how you know which colours to use for mixing.  Here’s why.

Choosing the right colours for mixing

Suppose you want to make green, for example. You mix yellow and blue, right? Yes, but you have a range of blues and yellows to choose from, so how do you know which ones to use?

That depends on the type of green you want to make. For olive green, you might use a warm yellow, such as yellow ochre, and a warm blue, such as ultramarine.  Both these colours contain a small amount of red. All three primary colours are then present in the mix, so the colour shifts towards neutral.

A warm blue mixed with a warm yellow is how you end up with a brownish (or olive) green.

So let’s look at cool colours. A cool yellow leans a little towards green, which means it contains a small amount of blue. A cool blue also leans towards green, so it contains a small amount of yellow. There is no red present in the mix at all, so the colour is pure, no brownish or grey tones.  

Greens made by mixing cool yellow and cool blue are perfect for painting the ocean.

When you mix a cool blue with warm yellow, or vice versa, another whole range of greens is available.  A warm and cool hue of blue and yellow will allow you to make any green you will ever need.

Add to that a warm and cool hue of red, and you can also make any orange, purple, brown, grey and black you will ever need.

Save time in working out exactly how to get any colour you want by making yourself a chart like this.

List all your paint colours along the top and then again down the side of the chart.  Start with the first colour in the top row of your chart.  Mix a little bit of that colour with each of the colours on the left hand side of your chart and paint a little swatch where they intersect in the table.  Do the same with each of the colours on the top row until you have completed the grid.  You now have a reference chart for every colour you can mix with your paints.  This should save you some time and frustration when you are looking to find exactly the right colour for your artworks.

Mixing grey, brown or black

Now suppose you want to make grey, brown or black.

As previously mentioned, neutral colours like grey and brown are made by mixing all three primary colours together, or mixing one colour with its complementary.  That is, you mix yellow with purple, blue with orange or red with green.  You will achieve all sorts of different greys and browns depending on which complementary colours you mix together.  You can also make black by mixing complementary colours together, but it does make a difference which paint colours you use.

Many of the paints you buy already contain quite a bit of white in them.  Some examples are Naples Yellow or Cerulean Blue.  It is also worth mentioning that the amount of white added will differ between paint brands.  When making black, it is important to use paints that have no white added to the tube.  If white is present, you will end up with grey.

There are lots of different ways to make black, but just like the primary colours, black will always lean slightly towards one or the other of the primary colours.  That’s why black paint from a tube is not always the best black to use in your paintings.  The black you should choose will depend on the other colours in your painting. 

Burnt sienna and Ultramarine Blue, or Pthalo Green and Napthol Crimson are two of my favourite combinations for mixing black.  Black will appear when you find the neutral point where all three primary colours are mixed evenly.

Mixing shadow colours

When any colour is mixed with only a small amount of its complementary, a toned-down version of the dominant colour is produced.  This toned-down version is what you should use when applying shadows to your paintings. 

Imagine you are painting a red apple sitting on a yellow table with light coming in from a window. A little green mixed into the red of the apple creates the perfect colour for the shaded side of the apple.  That is the self-shadow. The shadow of the apple that appears on the table is painted by mixing purple into the yellow table colour. That is the cast shadow.

The way to tone down a colour is to add a little bit of its complementary colour.  The amount of complementary colour you add will depend on how strong you want the shadow to be.  That will depend on the strength of the light source, or the tonal range of the painting.  For darker shadows, you would add a bit more of the complementary colour.  

For shadows on white objects, the same rules can apply because when painting sunlit areas of white objects, the colour will not be true white but will lean towards one colour or another.  Note:  I never use white paint to show white objects.  Instead, I use a very pale version of whichever colour gives the best contrast to the surrounding area.  More often than not, the shadow colour I use for white objects will be blue or purple.

Shadow colour chart

Here is another little exercise you can do work out all the different shadow colours, browns and greys you can make.

Start by painting a swatch of each of the three primary colours across the top of your page, red, yellow and blue.  At the bottom of the page paint a swatch of each secondary colour, green, purple and orange.  Each secondary colour should be directly beneath its complementary primary colour. 

Next you can start again at the top with any of the primary colours, say red, and mix in a little bit of green.  Paint a swatch of the mixed colour directly beneath the red at the top.  Then add a little bit more green to the mix and paint another swatch beneath that one. 

Repeat this process until you reach about halfway down the page.  At this point you want the two colours to be roughly a 50/50 mix.  Then you can work your way up from the bottom of the page, starting with the green, adding a little bit of red each time you move up the page. 

Repeat this process with the blue and the yellow and you now have a chart with all the different shadow colours, greys and browns that you can make yourself.

Key points to remember about mixing colours

Remember that warm colours are like the sun and cool colours are like the ocean.  

I recommend you have at least one warm and cool hue of each primary colours in your painting kit

Knowing whether your colours have a a warm or cool hue is going to help you to decide which colours to use for mixing

A colour wheel chart can be useful for identifying primary, secondary, tertiary and complementary colours

Complementary colours mixed together will tone down any colour so you can create browns, greys, blacks or any shadow colour.

As always in art, there are going to be situations where these rules don’t apply. One example is if there is reflected light in your painting.  However, the methods I have outlined above for identifying and mixing your own colours are a great place to start.  Hopefully, my suggestions will save you a bit of time and money.  You don’t need to buy endless tubes of paint of different colours when you know how to mix your own.

If you would like to learn more about colour mixing, with practical demonstrations, please check out the Colour Mixing Class at Blue Beach House Art School.