Passieve en actieve conservering van fossielen in het Natuurmuseum Rotterdam

In this article, the present situation as regards conservation of fossils and subfossils in the Natuurmuseum Rotterdam (NMR) is sketched. The collection consists mainly of materials of mammoths (M. primigenius), M. trogontherii, M. meridionalis), woolly rhino ( Coelodonta antiquitatis), giant deer ( Megaloceros giganteus), hippo’s, whales and micromammals. Many specimens show damages or degradation. The treatment focusses on restoration and conservation, active (consolidate) as well as passive (to optimize storage conditions, shock absorbing packaging). In the seventies, part of the collection has been treated with Velpon dissolved in aceton. However, this treatment has not only resulted in brown and yellowish colours and a glossy appearance of the fossils, but also could not prevent widening of the fissures and cracks. At present, the bones are first thoroughly desalinated with standard mains water, not with distilled water, as in that case also bone minerals will be dissolved together with the seawater minerals. After desalination the bones are treated with polyvinyl acetate (PVAc) as water dispersion, as wood glue D3 on the market. The dispersion is diluted with water in a ratio 1:20 to 1:30, till it is very watery. Bones are submerged till the air bubbles don’t appear anymore (vacuum systems accelerate this process), and dried afterwards. PVAc as water dispersion is safe, cheap, prevents the above mentioned disadvantages, and can also be used at home. Consolidating with PVAc is highly satisfactory in the case of small and medium sized objects.