Orange (colour) with green, of yellow with violet ... trying to make the colours intense and not a harmony of grey". In another letter he wrote simply, "there is no orange without blue." Van Gogh, Pierre-Auguste Renoir and many other impressionist and post-impressionist painters frequently placed orange against azure or cobalt blue, to make both colours appear brighter. The actual complement of orange is azure – a colour that is one quarter of the way between blue and green on the colour spectrum. The actual complementary colour of true blue is yellow. Orange pigments are largely in the ochre or cadmium families,
Orange (colour) a symbol of activity. Orange is sometimes used, like red and yellow, as a colour warning of possible danger or calling for caution. A skull against an orange background means a toxic substance or poison. In the colour system devised by the US Department of Homeland Security to measure the threat of terrorist attack, an orange level is second only to a red level. The US Manual on Uniform Traffic Control Devices specifies orange for use in temporary and construction signage. Because of its symbolic meaning as the orange colour of activity, orange is often used as the colour of