A stratigraphic and topographic examination of the polychromies of a small romanesque Madonna from Bertem near Louvain revealed ten consecutive layers of paint, which are fully described. Not knowing in what state of preservation the original polychromy remains, it was decided to take off the overpaints down to the third one, a 14th century well-preserved layer. On the basis of this case and of another one, a Madonna from Hermalle-sous-huy with eight layers of paint and cleaned in 1952 down to the 13th century polychromy, the author points out the importance of a sound knowledge of old techniques with responsible restorers. A laboratory analysis of structure and composition of the polychromies is given by L. Kockaert.