Repentir is a mobile application that employs marker-less tracking and augmented reality to enable gallery visitors to explore the under drawing and successive stages of pigment beneath an oil painting's surface. Repentir recognises the position and orientation of a specific painting within a photograph and precisely overlays images that were captured during that painting's creation. The viewer may then browse through the work's multiple states and closely examine its painted surface in one of two ways: scrolling or rubbing. Our current prototype recognises realist painter Nathan Walsh's most recent work, “Transamerica”. Repentir enables the viewer to explore intermediary stages in the painting’s development and see what is usually lost within the materially additive painting process. The prototype offers an innovative approach to digital reproduction and provides users with unique insights into the painter's working method.