The novel paste electrolyte measuring cell for EIS testing of the commonly used surface protection on bronze

Ines Soljic, Ivana Soic, Magdalena Eskinja, Adnan Mujezinovic, Sanja Martinez

Publikation: Beitrag in FachzeitschriftArtikelForschungBegutachtung


The cell was tested on polished and patinated bronzes of different compositions, on sulfide 14 patina/Paraloid B-72-coated bronzes with different numbers of coating layers, on protected 15 bronze samples with different degrees of damage to the protective layers, and on uncoated and 16 coated patinated bronzes after 24 h conditioning in the condensation chamber. A quantitative 17 criterion of Phase Angle at 0.1Hz was deduced and explained. The systems show two or three 18 time constants, depending on the number and integrity of the layers. Capacitances of the highfrequency response that are attributed to the coating range from 1.8 to 31 nF/cm2 19 and capacitances of the medium-frequency response attributed to the patina range from 1.1 F/cm2 20 to 2.3 nF/cm2 21 , indicating Paraloid B-72 penetration into the pores of the patina. Log ∣Z∣ at 22 0.1Hz decreases with mechanical damage to the protective layers. Damage also leads to the 23 occurrence of the low-frequency response attributed to the Faradaic process on the substrate. 24 The three layers of Paraloid B-72 on the sulfide patina had Log ∣Z∣ at 0.1Hz around 8 and were 25 insensitive to the 24-hour condensation, indicating good protection. The cell was further 26 applied to different sides of bronze coins, so no electrical contact with the substrate was 27 required. The Kramers-Kronig test was applied to confirm the validity of the EIS results.
FachzeitschriftProgress in organic coatings
PublikationsstatusVeröffentlicht - Apr. 2023

Bibliographische Notiz

Funding Information:
This work has been fully supported by Croatian Science Foundation under the project Development of new solutions for characterization and protection of bronze cultural heritage exposed to outdoor environment IP-2019-04-5030 .

Publisher Copyright:
© 2023 Elsevier B.V.

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