In this article is presented a procedure for the process synthesis, which is compound by the following stages: The identification or the primitive problem definition; the creation of alternative solutions, through the Douglas Hierarchical Decomposition method; the analysis of the considered alternatives; and finally the choice of the most reasonable solution. With the purpose to illustrate the last procedure is exposed an example of application made in a tannery, where are shown several considerations depending on heuristic rules, and their respective analysis, according to techniques, locatives and safety restrictions, in order to obtain the best solution in the process modification of finish's products evacuation which cannot be kept on the leather in a paint spray gun machine. The most appropriate solution was the selection and the installation of a spray tower, obtaining an efficiency of particulate matter retention close to 40%; thus, the environmental pollution generated was successfully reduced.