The transition from the archetypical effect of the uniformly luminous secondary surface to the more variegated textural light is once again due to an increase in the order of surface feature height of the receiving surface. When the surface features, surface geometry, or surface quality or patina are such that parts of the surface will collect or hold light while other areas are recessed or lost in shadow, textural light is at play. Even minute details can be revealed by a source that pushes light across an architectural surface.
Architecture can inform the intensity and directionality of incident light in order to express the materials and methods of its construction. Textural light most commonly exists when a source is narrowly framed and deployed along the edge of the surface plane with few or limited sources of light illuminating other areas of the room. Few additional sources are needed as this archetype of light often acts as a fractured secondary source, providing sufficient illumination for those tasks that do not require precise illumination. In The Eyes of the Skin, Juhani Pallasmaa describes materials that lend themselves to textural effects of light: "Natural materials - stone, brick and wood - allow our vision to penetrate their surfaces and enable us to become convinced of the veracity of matter."1
In some ways, the depth that is apparent when light interacts with these materials is the opposite of "the architectural mirror, that returns our gaze and doubles the world, [and] is an enigmatic and frightening device."2 Details in construction that capture the human endeavour of building are equally important in the realization of this archeytpe. In Peter Zumthor's renowned Therme Vals project, on-site masons were first disappointed when the slit-like apertures that bathe adjacent interior stone surfaces in light were opened. "The shafts of light washed the walls of their finished work causing tiny irregularities in the stone bond to cast dramatic shadows. But watching optical illusion, which at first seemed to suggest a job poorly done, soon turned into pure delight."3 The power of this archetype often lies in the subconscious history that is imparted to the viewer as they observe the phenomenon, be it a history of labour or fabrication.
Textural light is a friend of the shadow - it is through a balance of light and shadow that it exists, and it can continue to exist when this relationship skewed toward shadow until just the barest hint of direct or filtered light is registered by the non-uniform surface. Textural light engages both our visual and visceral senses of experience.
1. Juhani Pallasmaa, The Eyes of the Skin: Architecture and the Senses (Chichester: Wiley-Academy, 2005), 31.
2. Ibid.
3. Sigrid Hauser and Peter Zumthor, Peter Zumthor Therme Vals (Zurich: Scheidegger & Spiess, 2007), 113.