Blue in Barragán’s work is less a sky color than a way of pushing a plane back — it reads as distance and coolness rather than as a wall’s local hue. In Casa Gilardi two blue surfaces frame the dining room, giving the isolated red plane a field to sit against; in Plaza del Bebedero a single blue wall closes a long perspective axis.
The tone shifts with what’s near it: under direct sun it saturates toward ultramarine, in shadow it moves closer to indigo, and next to water it reads noticeably lighter and greener than the same pigment does on a dry wall. Barragán rarely fixed a wall’s final color from drawings alone — he tested large painted samples directly against the built wall under changing daylight before settling on one.
That sensitivity to a color’s neighbors is close to what Josef Albers described in his own studies of color interaction, and the parallel between the two has been argued directly rather than left as coincidence.