Retarding additive for flexography inks of the nitro-thermoresistant range. We produce it by using pure Methoxypropanol and pure Isopropyl Alcohol, in a percentage designed to form an azeotrope. Adding this ink mixture not only has a retarding function, it also limits problems due to a possible surplus dose of Methoxypropanol (such as ink yielding), further reduces the hygroscopicity of the mixture and offers a more balanced evaporation of the solvents.