Mixed precision techniques have become an important and sometimes necessary optimization direction for HPC applications for effective use of current generation supercomputers. Effective use of such techniques can result in significant speedups, but at the same time there are challenges in adopting such techniques, both practical and numerical. In this talk I discuss these topics, giving specific focus to Lattice Quantum Chromodynamics (LQCD) which is a regular top-cycle consumer of public supercomputers.