Crystal mounting for macromolecular crystallography typically involves exposing the crystals to ambient conditions for some period of time during looping. Our cryo-optimization experiments were difficult to interpret due to variation from dehydration during mounting. To combat these dehydration issues, we invented a new approach to crystal mounting, "vial mounting", which reduces variation from dehydration. Crystals are mounted directly on the cold stream from a vial in which the crystal is in vapor equilibrium with its cryosolution. A paper on this topic is here: