Page:Atlas of the Munsell color system.djvu/17



CHART

YELLOW AND PURPLE-BLUE CHART. This chart presents a vertical plane passed through the axis of the color solid and bearing the complementary hues, yellow and purple-blue. This pair of opposite hues is shown in regular measured scales from black to white, and from greyness to the strongest color made in stable pigment.

VALUES of yellow and purple-blue range vertically from black (0) to white (10). CHROMAS or strengths of color range horizontally from neutral gray to the maximum (10).

Each step in these color scales bears an appropriate symbol describing its light and its strength. Thus $Y 8⁄9$ is zinc yellow, the strongest permanent yellow, which exhibits 90% of chromatic strength and reflects 80% of the incident light. Its opposite $PB 8⁄2$ reflects the same percentage of light but only 20% of chroma. To balance this pair the areas must be inversely as the chroma, i.e., since purple-blue is but two ninths as strong as zinc yellow, it requires nine parts of purple-blue to balance two parts of the yellow. Attention to these measures leads to pleasing combinations.

Any chosen steps of yellow and purple-blue upon this chart may be balanced by noting their symbols:- thus light yellow ($Y 8⁄9$) balances dark purple-blue ($PB 3⁄9$), when the areas are inversely as the product of the symbols viz:- twenty-seven parts of light yellow and seventy-two parts of dark purple-blue.

Chapters III and IV of the handbook, "A Color notation," describe these balances and their combinations with other hues.

The symbol on each color step is its NAME, a measure of its light and strength by which it is to be memorized, written and reproduced.

AVOID DUST, HANDLING AND EXPOSURE TO STRONG LIGHT.