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 reflectance-Fourier transform infrared spectroscopy, optical microscopy, and scanning electron microscopy-energy dispersive x-ray spectroscopy showed two kinds of wax mixtures, one containing beeswax and potato or maize starch as filler, the other consisting of gypsum, zinc stearate, and a greasy substance. Upon examination a specific deterioration phenomenon was noticed where the wax models had been strengthened with internal metal armatures. A chemical reaction between the wax mixture and the copper-containing armature caused intense greenish coloring of the wax and created 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 modeling properties.