Penry Williams is high in key: pale, luminous, and filled with optical air. Temperature is cool-dominant, with blue and green families claiming the largest areas. Chroma is kept low across all colours, producing the soft, enveloping quality that characterises tonal painting. #966A2A delivers the chromatic peak at only 5.0% - a small shot of colour with outsized visual impact. At 58 units of value range, the palette has the tonal breadth to sustain complex spatial readings. High luminosity and cool temperature suggest the plein-air condition: unfiltered daylight and open sky. Palette 4 sits within the larger chromatic argument that Penry Williams's complete body of work advances.