Low-key values are the structural spine of portrait, giving it gravity and atmosphere. Yellow, ochre, sienna: warm hues deployed as the palette's primary energy. Saturation is deliberately withheld - the beauty here lies in the near-monochromatic gradations rather than colour difference. #B98A54 functions as the palette's exclamation mark: highest chroma, lowest percentage (4.8%). A value spread of 61 units gives the palette both depth and air - shadows are genuinely dark, lights genuinely light. The combination of low values, muted chroma, and compressed range is the signature of the Tonalist mode - painting as atmosphere.