Evaporation of ternary blends of water, with a fast and a slow cosolvent at various ambient conditions, was investigated using an abbreviated method in which computer analysis of a limited number of carefully chosen experiments reveals the independent effects of each variable and permits prediction of evaporation behavior at any set of conditions within the range investigated. Relative humidity was found to have the greatest effect, with temperature and composition following, in that order. Response of solvent balance to humidity and temperature is shown for various compositions, and evaporation time is compared to that of water under the same conditions. For example, evaporation of the ternary water-organic blends is usually slower than water at low humidity, but faster at high humidity. -- AATA