Trace of light is an interior design concept that utilizes photo-sensitive material to add aesthetic value to interior space. It employs an antique photographic process called cyanotype to visualize the evidence of light. Rather than using decorative material or artifacts, it uses sunshine and shadow to create genuine light paintings on walls and floors. 
It is subproject of my MID thesis project Time Sensitized which introduces the notion of time to a series of things which we usually consider still or atemporal, such as furniture, tools, buildings, etc.. Trace of light is inspired by sundial. As the sun is constantly moving, window light also changes its position and pattern over the day. The sensitized interior surfaces are transformed into a camera that captures the beauty of this natural, poetic phenomenon. 

A sketch model was made to test out scientific feasibility and to simulate the construction process. The wooden box is for simulating a interior space with openings which let light goes in as windows does. Cyanotype solution is coated onto paper which is trimmed to fit into the inner space. A 2 hours long exposure was done at a winter sunny afternoon. The result shows how the existence of light is visualized by pattern, color and tone, proving that the design could be realized at larger scale.