Notan is about the relationship of light and dark shapes. That relationship is not always one of balance, although the balance of light and dark obviously has resonance in Asian philosophy, expressed in the balanced opposition of yin and yang in Taoism for instance. The relationship is often one of tension, in which there is a deliberate imbalance, or in which the formal dominance of the light or dark is countered with the spacial dominance of the other, e.g a strong black shape in a large white field. It is also important to observe that in Japanese aesthetics notan is not limited to black and white, but is expressed in terms of light and dark. In the sumi-e style of painting, for instance, there may be no pure black or white at all, only shades of grey composed in areas of light and dark. In this context the notion of ‘good notan’ is obviously much more complex than mere balance.
The original Chinese characters, pronounced ‘nóng dàn’ in Chinese or ‘no-tan’ in Japanese refer to how dense the ink is you use in an ink watercolor painting. The solid ink is mixed with water, and can mixed either more dense and dark (nóng) or more dilute and light (dàn). How a painter handles ‘notan’ in an ink painting refers in the first place to how they handle the more and less dilute ink—the shades of grey—in the strokes themselves. But by extension the white is included in consideration of ‘notan’, and not just the strokes, as it is the most light or ‘dilute’ part of the painting. (A clear as opposed to dark sky is also described as ‘dàn’. It also refers to thin or weak soup or tea.)
The meaning and relevance of notan to type design is under increasing discussion, but many outstanding type designers, including Frutiger, have emphasized the importance of “designing the whites.”
Some of the people who have written about Notan as it relates to Type design on Typophile include : Hrant Papazian, William Berkson and Eben Sorkin.