AbstractA new concept of perfumery ternary diagrams (PTDs), based on an analogy between perfume pyramid structure and engineering ternary diagrams, is described. These diagrams allow a fast theoretical evaluation of the odor value in the headspace for all possible concentrations of a perfume liquid mixture constituted by three fragrant components and one solvent base, thus eliminating a long trial‐and‐error experimental work to analyze the headspace composition. The effect of the nonidealities in the liquid phase arising from molecular interactions was analyzed, as well as the effect of ethanol in a test mixture composed of limonene, geraniol, and vanillin. A diffusion model was used to simulate the evaporation of a small and finite sample of perfume test mixture. The changes in the liquid phase and in the gas–liquid interface were followed using the PTDs developed in this work. A characteristic point of a PTD was used as the initial mixture for simulating the evaporation of the small amount of perfume as a function of time and space. The performance parameters, such as impact, tenacity, diffusion, and volume, were discussed based on these results. © 2005 American Institute of Chemical Engineers AIChE J, 2005