Several analytical techniques can provide information about the elemental or molecular composition of metallic cultural heritage objects. But only electrochemical techniques can provide direct mechanistic and kinetic information of the corrosion process taking place on the metallic surface. While these techniques are routinely used in corrosion laboratories, their application for in-situ assessment of the corrosion of metallic cultural heritage is much less common. One of the main reasons for that is the difficulty of handling a liquid electrolyte on irregular, leaning and usually rough surfaces. In this chapter, a short historic review of the use of electrochemical techniques in conservation science is presented, paying special attention to different approaches for solving the issues of in-situ measurements. A new gel polymer electrolyte (G-PE) electrochemical cell, specifically developed by our research group for its application on metallic cultural heritage, is explained. This cell overcomes some of the shortcomings of previous developments, and has shown to provide results comparable to a traditional liquid cell. Examples are presented of its use in the comparison of the performance of different acrylic coatings for bare or patinated bronze, or the follow-up of the restoration treatment underwent on the bronze sphinxes of the National Archaeological Museum in Madrid.

This work has been funded by EU project “Integrated Platform for the European Research Infrastructure on Cultural Heritage” (IPERION-CH, Ref. H2020- INFRAIA-2014-2015, GRANT n° 654028), by project HAR2014-54893-R from the Ministerio de Economía, Industria y Competitividad (MINECO, Spain), and by Programme GEOMATERIALES 2-CM (S2013/MIT_2914) from the Community of Madrid. Authors also acknowledge the support by the Spanish Network TechnoHeritage,the Museo Arqueológico Nacional and Museo de Escultura de Leganés.

Advanced Characterization Techniques, Diagnostic Tools and Evaluation Methods in Heritage Science - David M. Bastidas; Emilio Cano