Low-key values are the structural spine of Juan del Castillo, giving it gravity and atmosphere. Temperature reads distinctly warm: the reds and earth tones from Juan del Castillo carry the compositional weight. Saturation is deliberately withheld - the beauty here lies in the near-monochromatic gradations rather than colour difference. A single dominant - #20251D at 28.6% - sets the character of the whole composition. At 1.8%, #DABD89 carries the palette's sharpest chromatic charge: an accent that earns its place precisely because it is withheld. At 59 units of value range, the palette has the tonal breadth to sustain complex spatial readings. This tonal restraint is characteristic of the Juan del Castillo approach: colour serves light, not the reverse. Juan del Castillo's palette 4 carries its own internal logic while remaining in conversation with the artist's broader colour intelligence.