This information is from the Frith Street Gallery (http://www.frithstreetgallery.com/): Since the early 90s, Ingrid Calame has been working with tracing. Her practice involves going to specific locations to trace marks, stains and cracks on the ground on to architectural polyester-based tracing film. From these tracings she make drawings and paintings. The original tracings are layered on top of each other and the resulting image is retraced in a different coloured pencil for each layer. Each sheet is peeled back one by one until Calame reaches the bottom of the pile. The final drawings are always a surprise.