A cleaving tool provides pressurized gas to the edge of a substrate to cleave the substrate at a selected interface. A substrate, such as a bonded substrate, is loaded into the cleaving tool, and two halves of the tool are brought together to apply a selected pressure to the substrate. A compliant pad of selected elastic resistance provides support to the substrate while allowing the substrate to expand during the cleaving process. Bringing the two halves of the tool together also compresses an edge seal against the perimeter of the substrate. A thin tube connected to a high-pressure gas source extends through the edge seal and provides a burst of gas to separate the substrate into at least two sheets. In a further embodiment, the perimeter of the substrate is struck with an edge prior to applying the gas pressure.