Practical Hard Sky

Greek praktikós, practical — adjectival suffix -al. As a color modifier, practical implies a clear-and-purpose-fit-and-everyday quality where the hue carries the visual register of Shaker-and-Quaker utilitarian-and-functional everyday-life craft. Sits at the crisp-and-functional end of the grid, parallel to functional and workmanlike in usage.

Old English heard, firm / hard. As a color modifier, hard implies a stone-and-iron-and-bone quality, the visual register of hand-hard-and-firm stone-and-iron-and-bone hard-and-firm-and-resistant tactile-hardness-and-firmness surfaces under hard-and-firm tactile-hardness light. Sits at the modifier-and-texture end of the grid, parallel to forged and hewn in usage.

The blue of a clear sky at noon — produced by Rayleigh scattering, the preferential dispersion of shorter wavelengths through atmospheric molecules. Air itself is colorless; the color we see is sunlight scattered toward our eyes by every cubic kilometer above. The reference shade is mid-latitude noon under a high pressure system: a clean, slightly green-shifted blue with the luminous depth of light scattered across an entire hemisphere of air.