One of the first things we learn about colour theory when starting to paint is that mixing a yellow and a blue produces a green. Followed quickly by the discovery the result depends not only on the proportions of the yellow:blue mix, but also which specific yellow and blue pigments are involved. Thus begins the quest for the perfect green, which I think ends only if you decide not to paint verdant landscapes.
1. The Easy Mix: Adding a Blue or Yellow to a Green
Adjust an existing green by adding another blue or yellow to it. (It’s not cheating!) Take some of the blue you?re using for the sky or sea or yellow from the sun to shift a tube green to better fit that particular landscape painting.
Tip: For a sense of early morning and late afternoon light, make your greens more golden yellow.
2. The Physical Mix: Blue and Yellow
Mix a blue with a yellow and you?ve a green. Vary the proportions and you?ve variations of that green. Mix the same blue with another yellow, and you?ve another green and yet more variations. Repeat through all the blue and yellow pigments we as painters have available to us, and you?ve all sorts of greens that become tricky to keep track of without creating a colour chart. Stick initially with a few blues/yellows until you know exactly what they?re going to do in a mix, then more onto other pigments; let the knowledge become instinctive through practice.
Tip: A little blue with shift the colour of a yellow more than the equivalent yellow in a blue.
3. The Optical Mix: Glazing
Glazing with blue over yellow or yellow over blue will also create green. An optical mix, where the layers of colour mix as we look at them, rather than a physical mix. The result can be richer, with more depth, than a single layer of a mixed colour.
Tip: Glaze over a mixed green if it turns out not to be exactly as you want it rather than trying to remove it.
4. The Secret Mix: Black and Yellow
Instead of a blue, use a black with yellow to mix earthy dark green. It seems unlikely, but you?ll be surprised at the result! My favourite is perylene black (Pbk31) which is often called perylene green because it has a strong green undertone to it. Remember, as with blues and yellows, different blacks and yellows produce different results, so experiment and make notes of what?s in the mixtures.
Tip: A little titanium white can help make the green more evident in a black:yellow mixture.
5. The Neutralizing Mix: Add Anything and Everything to a Green
If you add a red (the complementary colour to green) or a purple to a green you get useful grey- and brown-greens, which have all sorts of uses especially in landscape paintings. If you’re not feeling adventurous, first try using orange instead of yellow with blue.
Tip: Try it for greens in shadow areas.
Know What You?re Using
If you want to be able to repeat what you?re doing, check the paint tube label to see what pigment(s) is in a colour. Especially if you?re using different brands where the same colour names may not contain the same pigments. Check whether it?s a single-pigment green or a mixed green. It?s important because the more colours you have in a mixture, the sooner you end up with your brush in mud (brownish rather than vibrant mixtures).