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Fundamentals of Metal Conservation

Objectives

Evaluation of material condition. Understanding and recognition of corrosion mechanisms underlying. Fundamentals of preventive conservation and treatment methodologies applied to metallic materials. Examples for the most common cultural metallic materials, such as: silver, gold, copper, iron and tin alloys.

General characterization

Code

2677

Credits

6.0

Responsible teacher

Elin Maria Soares de Figueiredo, Rui Jorge Cordeiro Silva

Hours

Weekly - 5

Total - 86

Teaching language

Português

Prerequisites

- Basic knowledge of metallic materials and inorganic chemistry

Bibliography

  • ‘Notas para apoio à disciplina de Diagnóstico e Conservação de Metais’, textos elaborados por Rui Silva, 2004.
  • ‘Introdução à Corrosão nos Materiais Metálicos’, textos elaborados por Rui Silva.
  • ‘The elements of Archaelogical Conservation’ J. M. Cronyn, Ed. Routledge, 1990.
  • ‘The Corrosion and Conservation of Metallic Antiquities and Works of Arts’, T. Stambolov, CL publication, 1985.
  • ‘Atlas of Electrochemical Equilibria in Aqueous Solutions’ M. Pourbaix, NACE Int. Cebelcor, 1974.
  • ‘Ancient and Historic Metals. Conservation and Scientific Research’ (Proceedings), ed. D. A. Scott, J. Podany, B. B. Considine, The Getty Conservation Institute, 1991.
  • ‘Principles and Prevention of Corrosion’, Denny A. Jones, Prentice-Hall, 1996
  • Technical bulletins do CCI, CCI Notes, 9/1 a 9/7
  • Publicações diversas em Actas de encontros ou revistas científicas da especialidade.

    • Teaching method

    • The discipline has weekly theoretical-practical lessons and laboratories.
    • Transparencies or PowerPoint presentation is used for theoretical classes being the matter exposed in a class room when required.
    • Laboratorial classes are related to the experiences demonstration of the concepts already given in theoretical sessions. For demonstration purposes visits to museums and conservation labs are effectuated.

    Evaluation method

    - This course unit (CU) is composed of two assessment components: a theoretical-practical (TP) component and a practical (P) component (lab sessions). Each of these components is assigned a weight of 50% in the final classification.

    - The evaluation of the theoretical-practical component is carried out by 1 written test (quiz) and the evaluation of the practical component by carrying out laboratory work with final presentation of reports and discussion (20% individual participation in classes, 60% group reports and 20% oral presentation). The TP component will be evaluated in person; the P component will be evaluated in person.

    - Approval to the CU implies a positive assessment (> 9.5 out of 20 values) in each of the components.

    - The final classification (NF) counts the grade obtained in the theoretical-practical component (NT), obtained by test or exam, and the practical component (NP), according to the weight specified above. The formula for calculating the final classification is given by:

           NF = 0.5 NT + 0.5 NP,

    calculated by entering the grades in both componentes rounded to the nearest tenth.

    - Frequency is obtained if the student is not absent more than 1/3 of the P classes and obtains a positive assesment in P component. A positive assessment in the practical component (laboratory classes) is mandatory to obtain approval in the course unit or to access a final exam, necessary if the student has not yet obtained a positive assessment in the theoretical-practical component by test (quiz).

    - In the performance of any evaluation, the provisions of Article 10 n.3 of the FCT NOVA Evaluation Regulation are taken into account, "When fraud or plagiarism is proven, in any of the evaluation elements of a UC, the students directly involved are immediately disapproved in the UC (...).”.

    Subject matter

    Introduction

    • Introduction to materials diagnosis. Categories of object condition or conservation priority.
    • Corrosion. Atmospheric corrosion (characterization of atmospheric types in term of it relative humidity and pollutants agents).  Archaeological objects: basics of corrosion in soils and sea waters.
    • Conservation. Concepts of cleaning and stabilization, consolidation and reparation, protection and storing of metallic objects. Protective coatings (waxes and lacquers), storage boxes and bags, pollutants and oxygen absorber products and vapor phase inhibitors used in conservation of metallic objects.

    Silver and silver alloys

    • Corrosion under aerobic conditions (clean and pollutant atmospheres with sulfur sources). The tarnishing of silver objects. Corrosion in aqueous solutions containing chlorides and in other more complex environments, such sea waters and soils. Corrosion under anaerobic conditions and in the presence of sulfur reducing bacteria (SRB’s).  Appearance of decayed silver objects.
    • Conservation and intervention; care and cleaning, silver tarnish removal and removal of thick and hard corrosion products.

    Copper and copper alloys

    • Corrosion under aerobic conditions (clean and pollutant atmospheres with carbonate, sulphate and cloride sources). Corrosion in liquids. Corrosion of copper under anaerobic conditions (environment containing chlorides or sulphides). The Bronze disease. Examples. Appearance of decayed copper rich objects.
    • Conservation: removal of green copper products and stabilization of copper objects contaminated with chlorides. Use of inhibitors and protective coatings.
    Iron and Iron alloys
    • Corrosion under aerobic conditions (clean and pollutant atmospheres with carbonate, sulphate and chloride sources). Corrosion in liquids. Corrosion under anaerobic conditions and in the presence of sulfur reducing bacteria (SRB’s). The “Iron sweating” and the formation of “green rusts”. Examples. Appearance of decayed forged iron, cast iron and steels objects.
    • Conservation of objects with high chloride concentration (mechanical or electrolytic cleaning, chemical extraction, electrolytic and chemical reduction, Rust removal products. Protective coatings and passivation procedures.
    Tin And Tin alloys.
    • Corrosion under aerobic conditions (clean and pollutant with chlorides). Surface oxides and deterioration mechanisms. The “tin pest”. Corrosion in liquids. Appearance of decayed pewter objects.
    • Conservation of tin objects: cleaning, stabilization and coating.
    Other metals and Alloys

    • Corrosion in gold and lead rich alloys.

     

    Programs

    Programs where the course is taught: