The surface of beeswax seals shows a tendency to become covered with a white crystallic layer, composed mainly of unsaturated hydrocarbons. In order to obtain deeper insight into the nature of this adverse phenomenon, the thermal properties of the efflorescence and the pseudobinary mixtures efflorescence/beeswax were studied employing DSC and FTIR methods. The results are in agreement with the hypothesis that a primary cause of the problem is the limited miscibility of both pseudocomponents. Although a certain amount of alkenes can be "tolerated" in recrystallized beeswax, the resulting mixture is metastable. The possible delayed crystallization of alkenes is then connected with the development of the efflorescence. An understanding of the problem is important for suggesting reasonable conservation measures. (C) 2013 Elsevier B.V. All rights reserved.