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,
Gardner color scale Gardner color scale Gardner Color Scale is a one-dimensional scale to measure the shade of the color yellow. Colors of transparent liquids have been studied visually since the early 19th century. Changes in color can indicate contamination or impurities in the raw materials, process variations, or degradation of products over time. One dimensional scales for yellowness were created, e.g., Gardner Color Scale. The yellowness of the transparent liquid is determined by pouring the sample into a tube and comparing it to a pre determined and known standard. The standard that the sample falls closest to then becomes the value for