Indentation and abrasion in glass products: Lessons learned and yet to be learned

Glass has provided many life-changing products over the past millennia to improve the quality of human living. In this "International Year of Glass 2022" paper, we review the applied science and technology of indentation and abrasion damage in glass, highlighting its practical importance for commercial products. We briefly review what has already been learned from the several hundred high-quality publications on this topic. Though glass products have hard surfaces, indents, and abrasion arise upon contact with other glass and materials during manufacturing, transportation, subsequent user handling, and vandalism. The mechanical response of glass to impact is elastic-plastic, which generates several modes of cracks upon indentation. The science of deformations and stress generation is discussed in terms of theories by Hertz, Boussinesq, and Yoffe. The hydrostatic and shear yield strengths of the glass are suggested to be the more important parameters that govern hardness. Commercial opportunities for repairing or reducing damage from indents, particularly using diamond-like carbon coatings, are briefly discussed. Finally, challenges that lie ahead for a sustainable future of the Earth with increased commercial utility of beautiful glass products from increased damage resistance are outlined with emphasis on network topological principles and hard coatings.