Which colour can be added in a small amount to reduce the intensity of orange?

Correct answer: Blue

The governing concept is complementary neutralisation and saturation control. Blue is opposite orange on the traditional colour wheel, so adding a small amount of blue reduces orange’s intensity or saturation. Yellow or red generally strengthens the warm orange mixture, while white makes a tint by lightening it rather than neutralising its complementary intensity. Too much blue, however, can make the mixture dull or muddy.