This is part two of the series on colour mixing.
Darker colours
Did you know there is a way that the colours you already have can be tweaked to make them darker without using black. There is even away to darken a colour by adding a lighter colour to it.
Take a look at this example of colour mixing.
I made it darker by adding a lighter colour to it!
In this example I wanted to make our blue darker. The complimentary colour can be used to do this. The complimentary to violet-blues like this one are orange-yellows. By using a little warm yellow mixed into the blue it should go darker. And it does!
There is a point in the blend where you will see that the colour can be described as neither blue nor yellow. It is what we call a neutral colour. If we add a little more blue than yellow we should find our dark blue.
The dark colour at the top is made this way - just using the blue and that warm yellow. No black was used...promise!
We now have a new darker colour that will enhance our painting, and to our eyes relates somehow to the other colours used.
You can see how using this idea we could have made a darker yellow by adding a little blue-violet. Or for that matter we could darken a green by adding a spot of its complimentary - red.
So what's actually happening: The science bit.
The yellow pigment absorbs blue light. The Blue pigment absorbs yellow. Less light is able to be reflected back to our eyes. So the colour is darker.
The peculiar thing about the example above though, (and what is a little unexpected) is that the complimentary of our violet-blue colour is much lighter. So in this example we did add a lighter colour to make it go darker.
Which does seem strange.
Here is the tip
Make a colour darker by adding a little of it's complimentary (opposite).
If you add just a little you won't change the colour too much, you may want your blue to stay blue, it will just make it a touch darker.
however....
Dont forget there are loads of pigments out there and paint manufacturers use them to produce a huge range of colours in shades of light to dark. There may well be a darker option you could use. You might get the result you need by moving from the lighter cobalt blue say, toward a darker blue shade like phthalo blue maybe.
Don't forget...
You should choose carefully whenever you mix paints together. With watercolour particularly, painting with a single pigment paint (some paints are made of a blend of several pigments) will always give more luminous colours when mixing paints together. If you want pure brilliant colour use single pigment paints as much as possible. You can find out more about colour mixing on the Colour Mixing: Part 1 page.