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'Corrosion of gold alloy objects...'

2017 Research

Goldsmithery

Participation in the research project (2012-2017), called "Study of products and corrosion mechanisms from gold alloy objects to the development of conservation strategies for jewellery collections with cultural interest", for granting a PhD Scholarship in a business context, given to Isabel Tissot, by the Portuguese Foundation for Science and Technology and the company Archeofactu - Archaeology and Art, Ltd., under the scientific guidance of Maria Filomena Guerra and Maria Luisa de Carvalho Leonardo.
The identified research, hosted by the Centre for Atomic Physics, University of Lisbon, enrolls within the conservation and restoration of heritage for development of the study and research on methods of analysis and preservation of gold objects and its alloys, in order to obtain an intervention solution for this type of objects conservation and plans for preventive conservation of jewellery collections in museological context.
http://hdl.handle.net/10451/35143

Archer armband (c.1700 BC) from the *National Museum of Archaeology*, in Lisbon (Portugal). The corrosion layer shows a reddish colour with a multi-hued effect.

In-situ ellipsometric measurements during the corrosion of a gold alloy sample (A) and the electrochemical cell used for the in-situ measurements (B).

Portable XRF during the analysis of a gold necklace (NMA-Au47) from the collections of the *National Museum of Archaeology*.

SEM-EDS equipment (A) and detail of the SEM chamber prior to the exam and analysis of brooch *Ophelia* (CGM-1138) from the *René Lalique* collection of the *Calouste Gulbenkian Museum* (B).

Analysis of a torc fragment from Serpa (NMA-Au293) of the *National Museum of Archaeology* with the D8 Discover diffractometer from the *Laboratório José de Figueiredo*, Lisbon.

Iron Age torc from Codeçais, Bragança (NMA - Au 1139) and the detail of the terminal illustrating the corroded surface in 2009 (A) and 2012 (B and C).

SEM image of the blue fabric showing the wool fibres with scales characteristics of the wool fibres morphologies mixed with polyester fibres, exhibiting a flatter surface.

Bronze Age torc (MNA- Au 293) from Serpa (A); fragment of a Bronze Age torc (MNA-Au 283) from Alentejo (B) and Iron Age earring (MNA-Au 574) from Cabeço de Vaiamonte, Monforte (C).

Details of red corroded surfaces of the pendants *Peacocks on prunus* (CGM-1203) (A) and *Nymph in a tree* (CGM-1165) (B).

Fragment foil (GMA-432-25A) from Abydos excavations showing a heterogeneous corroded surface with colours varying from dark yellow, red and blue (A); and bead from Harageh (NMS-A1914.1096) with homogeneous corrosion with a red colour surface (B).