Quantitative Oddy test by the incorporation of the methodology of the ISO 11844 standard: A proof of concept

The Oddy test is a preventive conservation tool that helps to preserve real objects of cultural significance. To do this, it uses silver, copper and lead coupons as corrosion dosimeters. Despite its utility and ex-tensive experience, one of its limitations is the lack of a quantitative assessment method to avoid the subjectivity of visual examination and numerically rank the tested materials into suitable (permanent or temporary) and unsuitable. To address these issues, we present a proof of concept for the incorporation of the methodology of the ISO 11844-2 standard into the assessment stage of the '3 in 1 ' Oddy test. And so, use standardized quantification methods of corrosion rate for metal coupons such as electrochemical reduction for silver and copper coupons and gravimetric methods for lead coupon.A traditional '3 in 1 ' Oddy test has been performed to evaluate four materials known for their harmful nature to metallic cultural heritage: oak wood, medium density fibreboard (MDF), wool and leather. The electrochemical reduction method yields excellent results for copper and silver, allowing quantifying the corrosion even for the lightest tarnishing of the metal coupons that act as control or reference. For ex-ample, in the absence of contaminant-emitting material, the silver coupon lost 0.12 nm of thickness due to corrosion of the own conditions of the Oddy test (60 degrees C and 10 0%RH). Mass gain is also a convenient method with enough sensitivity to rank the corrosion of lead.It has been shown that the ranking established by visual inspection alone can be misleading, rating similarly materials that produce large differences in corrosion rates. Moreover, in the case of copper, the visual rating of the tested materials does not agree with that obtained from electrochemical reduction. Further research is needed to establish the limits of this methodology, but results presented here demon-strate the feasibility and utility of this approach.(c) 2022 The Author(s). Published by Elsevier Masson SAS.This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

Automated summary

The Oddy test is a preventive conservation tool that helps preserve real objects of cultural significance by using corrosion dosimeters. By incorporating the methodology of the ISO standard, a more accurate assessment of the corrosion of tested materials can be achieved.