The Danish sculptor Anne Marie Carl-Nielsen (1863-1945 often prepared three-dimensional models in wax before producing her works of art. The Carl Nielsen Museum in Odense keeps a unique collection of around 200 of the artist's fragile wax models. In 2008 the entire collection was examined, documented, X-ray radiographed, photographed, and conserved. Analyses of five figurines by attenuated total reflectanceFourier transform infrared spectroscopy, optical microscopy, and scanning electron microscopy-energy dispersive X-ray spectroscopy showed two different kinds of wax mixtures, one containing beeswax and potato or maize starch as filler, and the other consisting of gypsum, zinc stearate, and a greasy substance. During the examination a specific deterioration phenomenon was noticed in the areas where the wax models had been strengthened with internal metal armatures. A chemical reaction between the wax mixture and the copper containing armature has caused an intense greenish colouring of the wax as well as creating a soft and almost liquid consistency and formation of copper(II) carboxylate salts. Based on an original recipe from Anne Marie Carl-Nielsen, a replica of one of the wax mixtures was produced and examined with respect to its infrared spectrum and its modelling properties.