Color theory primary colors work at all is that the imperfect pigments being used have sloped absorption curves, and thus change color with concentration. A pigment that is pure red at high concentrations can behave more like magenta at low concentrations. This allows it to make purples that would otherwise be impossible. Likewise, a blue that is ultramarine at high concentrations appears cyan at low concentrations, allowing it to be used to mix green. Chromium red pigments can appear orange, and then yellow, as the concentration is reduced. It is even possible to mix very low concentrations of the blue mentioned and
Judo in Canada starting at first "dan" ("shodan") and ending at tenth "dan" ("judan"). Grades are also differentiated by belt colour. Kano originally adopted white and black belts in 1886 to mark the distinction between "kyū" and "dan" grades, and red and white and solid red belts were later introduced to distinguish judoka who were sixth "dan" and higher (collectively referred to as "kōdansha", or 'ones with high dan'). Coloured belts for "kyū" grades were first introduced by Mikinosuke Kawaishi in France in 1935 because he felt that European students would progress more quickly if they received visible recognition of their achievements. In