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 syllabus calls "6th+ "kyū""). The first five "dan" grades ("shodan" to "godan") are represented by a black belt. Judoka ranked sixth to eighth "dan" may wear a red and white belt, and those ranked ninth or tenth "dan" may wear a solid red belt, but this is not required and the black belt remains the standard for all "dan" grades. In the past women's belts would include a white stripe in the centre of the length of the belt to differentiate them from men, but this is much less common now. Promotions are regulated by Judo Canada using guidelines set