Beim Ritzen mit Diamantkegeln unter steigender Belastung des Werkzeuges läßt sich die plastische Verformung des Glases bis zu seiner Bruch- und Schollenbildung erkennen. Bei Flächenpressungen mit hohem Druck kommt es zu schollenartigen Ausbrüchen. Vor dem Werkzeug entsteht eine sich ausbreitende Rißlinie.

The film shows the changes occurring in the surface of glass which is deformed be means of scratching tools. The investigation was carried out with a scratching device having a similar mode of action to that of the Martens scratch hardness tester. During the scratching process, under increasing loading on the tool, the plastic deformation of the glass is seen, up to the point of fracture and flaking-off. Surface pressure of over 560 kp/mm2 are needed to produce the flaking tape of fractures. On scratching the surface of the glass with a conically-polished diamond cone, a scratch line can be observed spreading out in front of the tool. Diamond cones were used as scratching tools.