The quench test has been used by metallurgists for some time in order to probe the effectiveness of quench liquids for optimum properties of metals, e.g. steel. In preparation for "Apollo-11", cryo-liquids, such as Nitrogen, Hydrogen. Helium-4 and others have served to quantify conditions at reduced gravity. Recently perforated plates have been employed by our group extending the range of quench test geometry. Data obtained are compared with He I (normal phase of liquid Helium-4 above the lambda point) and liquid Nitrogen data. In general, geometry parameters and thermophysical properties exert an influence on heat transfer rates, e.g. Bond number and the ratio of gas phase enthalpy differences to latent heat of vaporization (Jacob number). He I data show a rather weak dependence on Bond number. This feature is accompanied by a relatively moderate change of the cooldown rate as "1g" is reduced toward milli-g and micro-g provided vapor removal is secured. In "Part I" of this contribution, cryo-liquid quench test evolution is outlined with focus on geometry and driving force comparisons achieved. In "Part II" details of recent perforated plate studies including flight data are considered.