Author/s: Fátima Marcos-Fernández1.2, Susana Bartolomé2, Elena Fernández Fernández2, Javier Fernández Martínez2, Irene Martínez Fernández2, Marta Onrubia1, Sofía Poblete1, Marina Ruíz Takamido1, and Francisco Ortega2
1 Facultad de Bellas Artes, UCM.C, España; 2 Grupo de Biología Evolutiva, Facultad de Ciencias, UNED. España
Vertebrate remains from the Late Cretaceous "Lo Hueco" fossil site (Fuentes, Cuenca, Spain) present conservation problems derived from the application of some methods for the elimination of the matrix (Marcos-Fernández, Plaza-Beltrán and Ortega, 2018). To avoid these problems, some alternative cleaning methods have been explored (Marcos-Fernández et al., 2020). In this context, the use of gels associated with EDTA has given positive results for removing iron crusts on vertebrate remains.
Different treatments have been proven by modifying the EDTA concentration, the amount of gelling agent and the action time of the gelled solution.
The treatment effectiveness was verified both by direct observation of the amount of crust that is dissolved in the gel and by the ability to facilitate its subsequent removal by mechanical methods.
Once the most suitable gelled solution has been determined, a treatment has been set. This treatment consists of applying a 150 ml solution of water with 7.5 g of EDTA and a drop of surfactant for 7 to 15 minutes. To gel the mixture, 6 g of carboxymethylcellulose and 3 g of neutralized polyacrylic acid (carbogel®) are used. To remove the gel and to neutralize the treatment, the application of paper pulp with demineralized water has been used until the gel is totally eliminated.
The treatment is slow but results are very effective since it allows for the removal of the iron crusts on the vertebrate remains from Lo Hueco but doesn’t affect the integrity of the fossil surface during the process.
References
Marcos-Fernández, F. et al. (2020) ‘Controlled chemical cleaning in paleontological preparation: the use of gels on vertebrate fossil remains from the Late Cretaceous of Spain’, Journal of Iberian Geology. doi: 10.1007/s41513-020-00129-w
Marcos-Fernández, F., Plaza-Beltrán, M. and Ortega, F. (2018) ‘La Conservación Preventiva de material paleontológico, la colección de Lo Hueco, the Preventive Conservation of paleontological material, Lo Hueco collection’, in GEIIC Kongresua Congreso 2018ko irailaren 20tik 22ra 20-22 de septiembre de 2018. Álava, pp. 402–410