Metal conservation

Conservation and restoration of metals is the activity devoted to the protection and preservation of historical (religious, artistic, technical and ethnographic) and archaeological objects made partly or entirely of metal. In it are included all activities aimed at preventing or slowing deterioration of items, as well as improving accessibility and readability of them as objects of cultural heritage. Despite the fact that metals are generally considered as the relatively permanent and stable materials, in contact with the environment they deteriorate gradually, some faster and some much slower. This applies especially to archaeological finds.

It is very important that a conservator of metals has knowledge of basic metalworking techniques, history of metalwork, history of art, archaeology, corrosion of metals, scientific research methods, theory and ethics of conservation-restoration.

Metals and alloys commonly used for cultural heritage objects

 * Bronze
 * Brass
 * Nickel silver
 * Monel
 * and Steel
 * Weathering steel (Corten)
 * Stainless steel
 * and Pewter
 * and Steel
 * Weathering steel (Corten)
 * Stainless steel
 * and Pewter
 * and Pewter
 * and Pewter

Metals and alloys less commonly used for cultural heritage objects

 * Electrum
 * Tumbaga
 * Shakudo
 * Shibuichi
 * Bidri
 * Hepatizon
 * Electrum
 * Tumbaga
 * Shakudo
 * Shibuichi
 * Bidri
 * Hepatizon
 * Hepatizon

Basic techniques

 * Casting
 * Forging
 * Folding
 * Sawing
 * Cutting
 * Bending
 * Drilling
 * Filing (metalworking)
 * Piercing
 * Sanding
 * Polishing

Joining techniques

 * Soldering
 * Welding
 * Mechanical joining
 * Gluing/cementing

Some supplementary techniques

 * Repousse
 * Chasing
 * Raising (metalwork)
 * Metal spinning
 * Annealing (metallurgy)

Surface decoration techniques

 * Enamelling
 * Niello
 * Engraving
 * Etching
 * Granulation
 * Filigree
 * Inlay (Damascening)
 * Mokume gane
 * Pattern welding
 * Plating
 * Chemical coloring of metals (Patination)
 * Heat coloring
 * Combining metals and other materials

Some contemporary techniques

 * Electroforming
 * Reticulation
 * Anodizing
 * Photoetching

Deterioration of metals
An essential cause of deterioration is corrosion of metal objects or object deterioration by interaction with the environment. As the most influential factors of deterioration of historical objects should be pointed out as the relative humidity and air pollution while in archaeological objects a crucial role has composition, depth, humidity and amount of gasses in the soil. In cases of marine or fresh water finds the most important factors of decay are the amount and composition of soluble salts, water depth, amount of dissolved gases, the direction of water currents and the role of both microscopic and macroscopic living organisms.

Deterioration of materials associated with metals
Associated materials deteriorate depending on the origin whether they are organic or inorganic materials. Organic materials usually fail in a relatively short period of time, primarily due to biodegradation. With inorganic materials are these processes considerably longer and more complex. Amount of gases, humidity, depth and composition of soil are very important. In case of salty and sweet water finds essential are amount of gases dissolved in water, depth of water, direction of currents, and microscopic and macroscopic living organisms.

Organic materials

 * Leather
 * Wood
 * Paper
 * Fur
 * Feathers
 * Textile
 * Bone
 * Horn
 * Tortoiseshell
 * Amber
 * Plant fiber
 * Shell
 * Pearls
 * Ivory
 * Coral
 * Jet (lignite)

Inorganic materials

 * Precious and semiprecious stones (Gemstone)
 * Glass
 * Enamel
 * Niello
 * Ceramics
 * Porcelain
 * Plastics

Basics
As with the conservation and restoration works on any other material, here are the basic tenets of conservation-restoration based on the quality of execution and the best possible preservation of cultural, historical and technological identity and integrity of objects. Minimal intervention, reversibility and repeatability of preferred treatment are essential, as well as the possibility of easy identification of restored parts. Recently non-toxic nature of used materials and procedures becomes important too, both in relation to objects and conservator-restorer as a performer, but also in relation to the environment.

Research
Nowadays scientific research is an integral part of the metals conservation treatment, at least in highly developed countries.

Identification of metals and alloys

 * Simple methods - visual examination, spot tests, specific gravity
 * Scientific methods - X-ray fluorescence, XRD, Particle-induced X-ray emission, LIBS, SEM, electrochemical techniques, metallography

Identification of corrosion processes and products

 * Simple method - visual examination, spot tests
 * The Oddy test - for copper, silver, and lead
 * Scientific methods - xrd, SEM, metallography

Identification of materials associated with metals
Raman spectroscopy
 * Simple methods - visual examination, spot tests, specific gravity
 * Scientific methods - xrf, chromatography,

Identification of technology used to produce objects

 * Simple methods - visual examination
 * Scientific mehods - metallography, x-ray radiography, x-ray computed tomography

Decision making
In preparing the strategy of the metals conservation project interdisciplinary approach to the same is essential. It implies the participation of as many experts as is possible, as a minimum, we can take curator (archaeologist, historian, art historian), scientists specialized for corrosion of metallic objects of cultural heritage and the conservator - restorer.

Documentation
Systematic and well-managed documentation is today an essential prerequisite for quality executed conservation and restoration treatments, including documentation of the state of objects before, during and after treatment. Identification of materials and procedures used to produce object and the results of any scientific research must be part of documentation too. Last but not least- an integral part of the documentation must be a recommendation for further care of object.

Ethics and ethical problems in metals conservation
The ethical concept of conservation of metal objects in principle is the same as those in other fields of conservation-restoration of cultural heritage.

But there are several specific problems that can only be found in the conservation of metals - problem of heat treatment of archaeological objects, and the problem of radical restoration of historic, mostly technical, but also architectonic objects too.

While in the first case problem is primarily in the destruction of valuable scientific data, in case of the technical, the architectural, and somewhat less often, historical objects problem is that a radically restored items just simulate the original appearance of the object, and so in some ways that objects can be considered even as, more or less successful fakes, which only superficially simulate long-lost or never existing state of object.

According to the above-mentioned, whenever it is possible real historical substance must be preserved. Thoroughly documented and technically professionally executed restoration of objects, must be avoided because such objects must be seen only as freshly painted surrogates of authentic historic substance.

Ethical problems connected with conservation of sacred metallic heritage objects can be included too.

Preventive conservation
Metallic heritage objects are sensitive to environmental conditions such as temperature, humidity, air pollution and exposure to light and ultraviolet light. They must be protected in a controlled environment where such variables are maintained within a range of damage-limiting levels.

Preventive conservation, also known as collections care, is an important element of museum policy. It is an essential responsibility of members of the museum profession to create and maintain a protective environment for the collections in their care, whether in store, on display, or in transit. A museum should carefully monitor the condition of collections to determine when an artifact requires conservation work and the services of a qualified conservator.

Cleaning


The most common procedure in conservation and restoration of metals is the cleaning process. This process can be distinguish between mechanical, chemical, electrochemical, ultrasonic, plasma and laser cleaning. In principle, it is aimed at removing dirt and corrosion products from the surface of a metal object. In many cases archaeology objects only can be cleaned mechanically.

Structural consolidation
Aimed at strengthening of the physical structure of the object, and correcting the shape of the object.
 * Mechanical joining - riveting / tab and slot / overlapping / screws
 * Soldering - soft / hard
 * Welding - oxyacetilene / electric arc / TIG / tack / laser
 * Gluing/Cementing
 * Reconstructions -in original material - in polymers - *3D printing

Reconstruction of missing parts or surface decoration
In certain cases, metals conservator must re-create the lost parts of objects or restore original surface decoration. This approach is accurate only if we have an exact documentation or photographs of items in a complete, currently non-existent state that we want to return.

New parts must be clearly and visibly marked and at least they must be minimally different from the original historic material.

If needed, those parts must be easily and completely removable from the object, and with methods which will not harm it.

Only cyanide or hexchromate free processes must be used.

Only worn-out spots can be replated.

Replating of entire object must be avoided.

Stabilization
Focused on slowing of deterioration of objects - in case of archaeology objects the thorough removal or blocking of chloride salts. In case of the historical objects it is focused on the use of corrosion inhibitors, conversion coatings, rust converters or eventually oxygen free storage.
 * Chloride removal (chemical processes, electrochemical processes)
 * Corrosion inhibitors (benzotriazole, tannin)
 * Rust converters˙
 * Conversion coatings (phosphate conversion coatings, phosphate/tannin, etc.)
 * Oxygen free storage

Protective Coatings
Still mainly focused on use of clear coats and waxes, in case of technology objects oil coatings can be used too. In general it supports the stabilization process. Paraloid B-72
 * Clear coats:

durable and non yellowing acrylic resin, chemically an ethyl methacrylate copolymer. It can be used for conservation of metals. Soluble in acetone, toluene, xylene, Shell Cyclo Sol® 100/Shell Cyclo Sol® 53, Arcosolv® PM/1-Methoxy-2-propanol.

Paraloid B 67 is acrylic resin, chemically it is an isobutyl methacrylate polymer. Soluble in toluene, xylene, acetone, Shell Cyclo Sol® 100/Shell Cyclo Sol® 53, Arcosolv® PM/1-Methoxy-2-propanol and white spirit acetone mixture (90 parts white spirit/10 parts acetone).

Paraloid B 44

is acrylic resin, chemically it is composed of methyl methacrylate and ethyl acrylate copolymer. Soluble in toluene, xylene, acetone. It is used for paints and clear coating for metals. It is ingredient in Incralac metal coating.

Paraloid B 48 N

is acrylic resin, chemically it is copolymer of methyl methacrylate and butyl acrylate. It is used as a clear coating for metals - copper, brass, bronze, and zinc. Soluble in toluene, xylene, methyl ethyl ketone, and acetone

Incralac

is special proprietary clear coat for copper and its alloys. It is based on Paraloid B 44 acryilic resin dissolved in toluene. It contains benzotriazole as copper corrosion inhibitor too.

Nitrocellulose lacquer

is solvent based lacquer that contain nitrocellulose, a resin obtained from the nitration of cotton and other cellulostic materials. Can be used on silver objects. Frigilene, Agateen No.27 and Perlitol RE 1260 are good brands.

ORMOCER

Organically modified ceramic, also known as ORMOCER (ORganically MOdified CERamic) is a type of coating used in the conservation of metals. ORMOCER was originally developed by the Fraunhofer Society for the Advancement of Applied Research in Munich. While it is still in research phase, ORMOCER is essentially a heteropolysiloxane-based clear coat.

Other used varnishes or lacquers that would be worthwhile to examine: 

Pantarol A (German product), the use of it is mentioned in German literature, according to manufacturer it is special acrylic coating for metal

Everbrite ProtectaClear Coating,Everbrite Coating (USA products) -  worthwhile to be tested, according to  manufacturer  product is easily removable from treated objects

'''Renaissance Wax
 * Waxes:

is a brand of microcrystalline wax polish that is widely encountered in antique restoration and museum curation. Although not appropriate for all materials, it is known to and used by almost every collection. It is also used as a primary finish for cabinetry and furniture. Renaissance wax is also used by reenactors of historic swordsmanship to protect armour and weapons. It is widely recognised that this substance is more protective and longer lasting than oil, especially for swords and helmets that are frequently touched by human hands.

To quote a typical commercial supplier of conservation materials, it is used, to revive and protect valuable furniture, leather, paintings, metals, marble, onyx, ivory etc. Freshens colours and imparts a soft sheen

Cosmolloid 80 H

is refined white microcrystalline wax. It can be used on historical and archaeological metals. Melting point 60–94 °C. Soluble in benzol, ether, chloroform, carbon disulfide, carbon tetrachloride, turpentine, petroleum distillates, and fixed oils; partially soluble in acetone, diacetone alcohol. Main ingredient in Renaissance Wax. Dinitrol 4010

is a long-term engine protection proprietary product with heat resistance up to 200 °C. It leaves a firm transparent film with short drying time and good adhesion and flexibility on all metal surfaces, rubber and plastic parts. Dinitrol 4010 is resistant to alkali and acidic solutions. According to some research articles it can be used on metallic heritage objects too

Poligen ES 91 009

is patented wax emulsion (BASF), according to some sources better than Paraloid B 72


 * Oils

-WD 40 / Ballistol / 80 parts white spirit+20 parts fish oil


 * Combinations

-base coat Paraloid B 72 / topcoat Renaissance Wax etc.

Precious and semi precious stones
In principle do not use any solvent, but only distilled water, or a 10% solution of soapwort plant (Saponaria officinalis). You must be Especially careful when working on porous gemstones like malachite, opal, chalcedony, chrysoprase, agate, carnelian, lapis lazuli, jade and turquoise. Special attention requires gemstones combined with colored metal foils, in this case, the liquid does not come into contact with the foil. Do not use ultrasonic cleaning.

Niello
Nielloed items can be cleaned only mechanically, never try to use chemical cleaning. Black pigment mixed with Paraloid B 72 can be used for reconnstruction of missing parts. Concentrated solution of Paraloid B 72 or B 67 (soluble in white spirit) can be used as reversible glue.

Amber
Do not clean with solvents, do not use ultrasound, you can use only distilled water, or a mixture of water and ethanol (add up to 0.5% crosslinker). Variety of waxy resin mixtures can be used as glue, depending on the color of amber. You can use 10% solution of Canada balsam in toluene Archaeological material can be cleaned only mechanically. Soaking in liquid paraffin can be used to consolidate and improve color of amber. According to one Korean article for consolidation can be used Paraloid B 67 dissolved in xylene (proved more stable than white spirit, usual solvent for B 67) Artifacts must be Protected from strong light and high temperatures, low humidity and oscillations in humidity, in the case of metal/amber objects do not to use corrosion inhibitors.

Oriental lacquer - urushi
Requires a completely different approach than western lacquers. May be found on the Japanese arms and armour. The best approach – leave it to expert for oriental lacquer. Mixture of 6-8% polyvinyl alcohol and chalk can be used as filling material(Rhoplex WS 24 can be used too). Japanese conservators use traditional techniques, but as Urushi causes allergic reactions, these methods are not recommended. Clean it with an aliphatic hydrocarbon such as white or mineral spirits. Distilled water or saliva (moistened cottonwool swabs) can caused discoloration and should be avoided by the inexperienced: pH is crucial. Keep objects in rooms with controlled humidity and temperature, preferably about 50% RH, and protect them from UV radiation.

Coral
Can be cleaned with cotton wool swabs soaked in distilled water, or with a mixture of distilled water and ethanol. Do not use ultrasound. Avoid any contact with acids.

Pearls
Historical objects can be cleaned using a mixture of 70% ethanol and 30% weak ammonia water (1%). To remove the surface layer that has lost luster you can use 3-5% EDTA, after that step rinse with distilled water, and then with 80% ethanol, then with 90% ethanol, and finally with pure ethanol. Do not use ultrasound. Archaeological finds must be treated as soon as possible, preferably after excavation, you can clean them only mechanically, then consolidate with 2% Paraloid B 72, in the case of dry findings (first saturate with solvent in which it is dissolved), in case of damp or wet findings use Rhoplex WS 24 (acrylic dispersion). Somewhat More recent Russian literature recommends use of bleached beeswax dissolved in white spirit or medical benzine as protective coating. Fish glue mixed with water and alcohol (7/3), with addition of 1% katamine AB as biocide can be used as glue. Nonionogenic detergent 2-3% in a mixture of water and alcohol can be used for cleaning. Avoid prolonged contact with water, sudden changes in temperature and relative humidity, including strong light or contact with acidic or alkaline solutions (soap water too).

Jet
You can clean it with cottonwool swabs soaked in distilled water or soapwort extract (Saponaria officinalis, 100 grams of dried root per 1 liter of boiling water). Archaeological material can be cleaned only mechanically. Wax/resin mixtures or concentrated solution of Paraloid B 72 (or B 67) can used as glue for archaeology objects.

Glass
Main article Conservation and restoration of glass objects

Plaster
Unsealed plaster can be cleaned with soft brush only; never try to use water or water-based cleaning solutions. Sealed plaster can be cleaned with a swab dampened with water or white spirit.

Replicas and Copies

 * molding (process)
 * casting
 * electroforming
 * 3D printing

Storage of metallic heritage objects
The items should be stored in rooms that are protected from polluted air, dust, ultraviolet radiation, and excessive relative humidity - ideal values are temperature of 16-20 °C and up to 40% (35-55% according to recent Canadian Conservation Institute recommendations) relative humidity, noting that if metal is combined with organic materials, relative humidity should not be below 45%. Archaeological objects must be stored in rooms (or plastic boxes) with very low relative humidity, or in the case of particularly valuable items in the chambers with or. Copper or copper alloy objects with active corrosion up to 35% RH. Iron objects with active corrosion 12-15% RH. Shelves in the storerooms must be of stainless steel or chlorine and acetate free plastic or powder coated steel. Wood and wood based products (Particle board, plywood) must be avoided. Also do not use rubber, felt or wool. When you are handling metal objects, always wear clean cotton gloves. Lighting levels must be kept below 300 lux (up to 150 lux in case of lacquered or painted objects, up to 50 lux in case of objects with light sensitive materials)

Important persons

 * Gustav Rosenberg
 * William Matthew Flinders Petrie
 * Friedrich Rathgen
 * Alexander Scott
 * Harold Plenderleith
 * Mstislav Vladimirovich Farmakovskiy
 * Albert France-Lanord
 * Robert M. Organ
 * Hanna Jedrzejewska
 * Joachim Szvetnik

Specializations within the profession

 * Conservation of Historical Metal Objects
 * Conservation of Archaeological Metal Objects
 * Conservation of Technological Metal Objects
 * Conservation of Ethnographic Metal Objects
 * Conservation of Architectural Metal Objects
 * Conservation of Metal Sculpture
 * Conservation of Gold and Silversmiths Works
 * Conservation of Arms and Armour

USA

 * Buffalo State College, Art Conservation Department, objects specialization
 * UCLA/Getty Masters Program - Conservation of Archaeological and Ethnographic Materials
 * Winterthur/University of Delaware Program in Art Conservation, objects specialization

Canada

 * Queens University, Art Conservation, objects specialization
 * Fleming College, Collections Conservation and Management

Mexico

 * Escuela nacional de conservacion, restauracion y museografia, Ciudad de Mexico, Diplomado de Especialización en Patrimonio Metálico

South America
Centro Nacional de Conservacion y Restauracion, Santiago de Chile, objetos arqueológicos, etnográficos e históricos Universidad Nacional Mayor de San Marcos, Escuela academico profesional de Conservación y Restauración Universidade Federal de Pelotas, Instituto de Ciências Humanas, Laboratório Multidisciplinar de Investigação Arqueológica (LÂMINA)
 * Chile
 * Perú
 * Brasil

Africa
1.Conservation Department, Faculty of Archaeology, Cairo University
 * Egypt

2.Conservation Department,Faculty of Archaeology, Fayoum University

The South African Institute for Objects Conservation, Joubertina, Eastern Cape, metals conservation
 * South Africa

Australia
The University of Melbourne, Centre for Cultural Materials Conservation

Europe
Universitaet fuer Angewandte Kunst, Wien, Konservierung/Restaurierung von Objekten
 * Austria

Koninklijke Academie voor schone kunsten, Antwerpen, metalen conservatie
 * Belgium

1. Sveučilište u Dubrovniku, konzervacija restauracija metala (BA+MA)
 * Croatia

2. Umjetnička akademija u Splitu, Konzervacija restauracija metala (BA+MA)

The Royal Danish Academy of Fine Arts, School of Conservation
 * Denmark

Konzervování-restaurování uměleckořemeslných děl z kovů, Turnov
 * Czech Republic


 * France
 * 1) Université Panthéon-Sorbonne Paris I, Paris,Conservation and restoration department
 * 2) Institut de Formation des Restaurateurs d’Oeuvres d'Art ,Institut National du Patrimoine,Saint-Denis-la-Plaine,Metals conservation

Metropolia University of Applied Sciences, Helsinki, objects conservation
 * Finland


 * Germany
 * 1) Roemisch Germanisches Zentralmuseum, Mainz, Ausbildung zum Restaurator des Fachbereischs Archeologie
 * 2) Hochschule fuer Technik und Wirtschaft, Berlin, schwerpunkt Archaeologisch-Historisches Kulturgut
 * 3) Staatlische Akademie der Bildende Kuenste, Stuttgart, Objekt Restaurierung
 * 4) Fachhochschule Potsdam, Metallkonservierung
 * 5) University of Applied Sciences Erfurt, Archäologisches Kulturgut und kunsthandwerkliche Objekte

Technological Educational Institution (TEI),Athens
 * Greece

Hungarian Academy of Fine Arts, Budapest, conservation of metalwork and goldsmiths works
 * Hungary


 * Italy
 * 1) Instituto Superiore per la Conservazione e il Restauro, Roma
 * 2) Opificio delle Pietre Dure, Firenze

Universiteit van Amsterdam, Amsterdam, MA metaalrestauratie
 * Netherlands

Nicolaus Copernicus University in Torun, Institute of Fine Art, Department of Conservation and Restoration of Historic and Artistic Works, graduate program, metal conservation
 * Poland

Faculdade de Ciências e Tecnologia da Universidade Nova, Lisboa
 * Portugal


 * United Kingdom
 * 1) West Dean College, metalwork conservation
 * 2) University of Sussex, metalwork conservation


 * Spain
 * 1) Universidad de Granada, Grado en conservación y restauración de bienes culturales
 * 2) Escuela Superior de Conservación y Restauración de Bienes Culturales, Madrid, Especialidad de bienes arqueológicos
 * 3) Escuela Superior de Conservación y Restauración de Bienes Culturales, Barcelona, Especialidad de bienes arqueológicos
 * 4) Escuela Superior de Conservación y Restauración de Bienes Culturales, Pontevedra, Especialidad de bienes arqueológicos

La Chaux de Fonds, Haute Ecole de Conservation-restauration Arc, objects conservation
 * Switzerland

Ukraine
Lvov Academy of Arts,metals conservation

Russian Federation

 * Факультет искусства реставрации Московской государственной художественно-промышленной академии им.С. Г. Строганова, Moscow-katedra"Restavraciya hudozhestvennogo metalla" (Conservation of artistic metalwork)

India
NATIONAL MUSEUM  INSTITUTE of History of Art, Conservation and Museology (Deemed to be University) Ministry of Culture, Government of India,New Delhi

Iran
1. Art University of Isfahan, Faculty of Conservation, Department for Conservation of Art Objects

2. Tabriz Islamic Art University, Conservation Department

Pakistan
Hazara University,Mansehra

Quatar
University College London, in partnership with Qatar Foundation and Qatar Museums Authority, Doha, objects conservation

Turkey
Gazi University, Faculty of Fine Arts, Ankara, conservation department

Jordan
Faculty of Archaeology and Anthropology,Yarmouk University

Essential literature

 * 1) Corrosion and metal artifacts : a dialogue between conservators and archaeologists and corrosion scientists, Washington 1977.(online)
 * 2) Conservation & restoration of metals : proceedings of the symposium held in Edinburgh, 30–31 March 1979., Edinburgh 1979.
 * 3) Stambolov, T. The corrosion and conservation of metallic antiquities and works of art - a preliminary survey, Amsterdam 1985.
 * 4) Corrosion inhibitors in conservation: The Proceedings of the conference held by UKIC in association with the Museum of London, London 1985.
 * 5) Pearson, C. Conservation of Marine Archaeological Objects, London 1987.
 * 6) Conservation of metal statuary and architectural decoration in open-air exposure : symposium, Paris, 6. - 8. X. 1986 = Conservation des oeuvres d'art et décorations en métal exposées en plein air, Rome 1987.
 * 7) Townsend, J.H.; Child, R.E. Modern metals in museums, Cardiff 1988.
 * 8) Metals Conservation: 7th International Restorer Seminar, Veszprem, Veszprem 1989.
 * 9) Brown, B. ; Burnett, H. ; Chase, W. T. ; Goodway, M., Corrosion and metal artifacts : A dialogue between conservators and archaeologists and corrosion scientists, Houston  1991
 * 10) METAL 95, Proceedings of International Conference on Metal Conservation, London 1997.
 * 11) METAL 98, Proceedings of International Conference on Metal Conservation, London 1999.
 * 12) METAL 01, Proceedings of International Conference on Metal Conservation, Perth 2002.
 * 13) METAL 04, Proceedings of International Conference on Metal Conservation, Canberra 2005.(online)
 * 14) METAL 07, Proceedings of International Conference on Metal Conservation, Amsterdam 2007.
 * 15) METAL 2010, Proceedings of International Conference on Metal Conservation, Charleston 2011.
 * 16) METAL 2013.Proceedings of Internationsl Conference on Metal Conservation,Edinburgh 2013.(online)
 * 17) Scott, D.A. Metallography and Microstructure of Ancient and Historic Metals, Santa Monica 1991.(online)
 * 18) Scott, D.A. Ancient and Historic Metals-Conservation and Scientific Research, Santa Monica 1994.(online)
 * 19) Scott, D.A. Copper and Bronze in Art-Corrosion, Colorants, Conservation, Los Angeles 2002.
 * 20) Scott, D.A. Iron and Steel in Art-Corrosion, Colorants, Conservation, London 2009.
 * 21) Scott, D. A. Ancient Metals: Microstructure and Metallurgy Volume I ,Los Angeles 2011.
 * 22) Scott, D. A. Gold and Platinum Metallurgy of Ancient Colombia and Ecuador.: Ancient Metals: Microstructure and Metallurgy Volume II,Los Angeles 2012.
 * 23) Scott, D. A. ANCIENT METALS: MICROSTRUCTURE ANDMETALLURGY Volume III CATALOGUE OF ANCIENT COLOMBIAN DATA.,Los Angeles 2012.
 * 24) Scott, D. A. Ancient Metals: Microstructure and Metallurgy Vol. IV: Iron and Steel.,Los Angeles 2013.
 * 25) JAIN KAMAL K., NARAIN Shyam, Iron artifacts history, metallurgy, corrosion and conservation, Delhi, Agam Kala Prakashan, 2009, XXII-165 p.
 * 26) Selwyn, L. Metals and Corrosion-A Handbook for Conservation Professional, Ottawa 2004.
 * 27) Draymann-Weiser, T. Gilded Metals-History, Technology, Conservation, London 2000.
 * 28) Draymann-Weiser, T. Dialogue/89 - The conservation of bronze sculpture in the outdoor environment : a dialogue among conservators, curators, environmental scientists, and corrosion engineers, Houston 1992.
 * 29) Dillman, P.; Beranger, G.; Piccardo, P.; Matthiesen, H. Corrosion of metallic heritage artefacts-Investigation, Conservation and Prediction of long term behaviour, Cambridge 2007.
 * 30) Cronyn, J.M. The Elements of Archaeological Conservation, London 1990.
 * 31) Turner-Walker,G. A Practical Guide to the Care and Conservation of Metals,Taipei 2008.
 * 32) Rodgers, B. The Archaeologist Manual for Conservation-A Guide to Non-toxic, Minimal Intervention Artifact Stabilization, New York 2004.
 * 33) Stuart, B. Analytical Techniques in Materials Conservation, Chichester 2007.
 * 34) May, E.; Jones, M. Conservation Science-Heritage Materials, Cambridge 2006.
 * 35) Untracht, O. Metal Techniques for Craftsmen, New York 1968.
 * 36) La Niece, S.; Craddock, P. Metal Plating and Patination: Cultural, Technical and Historical Developments, Boston 1993.
 * 37) Anheuser, K.; Werner, C. (Eds.) Medieval Reliquary Shrines and Precious Metalwork / Châsses-reliquaires et Orfèvrerie Médiévales, London 2006.
 * 38) Horie, C.V. Materials for Conservation, Oxford 2010.
 * 39) Smith, R.D. Make all sure : the conservation and restoration of arms and armour, Leeds 2006.
 * 40) Appelbaum, B. Conservation Treatment Methodology, New York 2007.
 * 41) Practical Building Conservation!Metals and Glass, Farnham 2012.
 * 42) Dillmann, P., Watkinson, D., Angelini, E., Adriaens, A., (Ed.) Corrosion and conservation of cultural heritage metallic artefacts, Cambridge 2013.
 * 43) Risser,E.;Saunders,D. The  Restoration of Ancient  Bronzes - Naples and Beyond,Los Angeles 2013.(online)

Some important books on metal conservation in languages other than English

 * 1) Mourey, W. La conservation des antiquités métalliques, du chantier de fouilles au musée, Draguignan 1987.
 * 2) Stambolov, T.; Bleck, R.D.; Eichelmann, N. Korrosion und Konservierung von Kunst und Kulturgut aus Metall, Weimar I/1987. (online), II/1988. (online)
 * 3)  Шемаханская, М.С. РЕСТАВРАЦИЯ МЕТАЛЛА. Методические рекомендации (1989), Moscow 1989. (online)
 * 4) Никитин, М.К., Мельникова,Е.П. ХИМИЯ В РЕСТАВРАЦИИ. СПРАВОЧНОЕ ПОСОБИЕ.; Leningrad 1990 (chapter on metals conservation) (online)
 * 5) Born, H. Restaurierung Antike Bronzewaffen, Mainz 1993.
 * 6) Heinrich, P. (Hrsg.) Metallrestaurierung, Munich 1994.
 * 7) Catello, C. Argenti antichi : tecnologia restauro conservazione : rifacimenti e falsificazioni, Naples 1994.
 * 8) Marabelli, M. Conservazione e restauro dei metalli d`arte, Rome 1995.
 * 9) Krause, J. Sarkofagi cynowe : problematyka technologiczna warsztatowa i konserwatorska, Torun 1995.
 * 10) Dolcini, L. Il restauro delle oreficerie: aggiornamenti, Milan 1996.
 * 11) Mach, M. Metallrestaurierung/Metal Restoration, Munich 1997.
 * 12) Fischer, A. Reste von organischen Materialien an Bodenfunden aus Metall – Identifizierung und Erhaltung für die archäologische Forschung, Munich 1997.
 * 13) Minzhulin, O.I. Restavraciya tvoriv z metalu, Kiev 1998.
 * 14) Anheuser, K. Im Feuer Vergoldet, AdR-Schriftenreihe zur Restaurierung und Grabungstechnik, Band 4 / 1998.
 * 15) Mach, M.; Moetnner, P. Zinkguß, die Konservierung von Denkmälern aus Zink, Munich 1999.
 * 16) Barrandon, J.N.; Meyer-Roudet, H. A la recherche du métal perdu : nouvelles technologies dans la restauration des métaux archéologiques, Paris 1999.
 * 17) Meissner, B.; Doktor, A.; Mach, M. Bronze und Galvanoplastik-Geschichte-Materialanalyse-Restaurierung, Dresden 2000. (online)
 * 18) Volfovsky, C.; Philippon, J. La Conservation des metaux, Paris 2001.
 * 19) Brueggerhoff, S.; Koenigfeld, P. Farbige Eisengitter der Barockzeit: Beiträge zu Geschichte und Funktion, Korrosion und Konservierung, Bochum 2002.
 * 20) Melucca Vaccaro, A.; De Palma, G. I Bronzi di Riace : restauro come conoscenza : 1: archeologia, restauro, conservazione/vol.1, Roma 2003.
 * 21) Gaomez Moral, F.  Conservacion De Metales De Interes Cultural, Quito 2004.
 * 22) Letardi, P.; Trentin, I.; Cutugno, G. Monumenti in bronzo all'aperto. Esperienze di conservazione e confronto., Genova 2004.
 * 23) Ronald Gobiet (Ed.), Die Salzburger Mariensäule - Zur Konservierung monumentaler Bleiplastiken / Sulla conservazione dei monumenti in piombo, Salzburg 2006.
 * 24) Salvi, A. Meteo e metalli. Conservazione e restauro delle sculture al aperto. Dal Perseo all arte contemporanea, Florence 2007.
 * 25) Catello, D Il restauro delle opere in argento. Restoration of silver artifacts, Naples 2008.
 * 26) Schlaepfer, B.R. Metais: Restauracao e conservacao, Rio de Janeiro 2009.
 * 27) Barrio, J.; Cano, E. (Editores). MetalEspaña ’08. Congreso de Conservación y Restauración del Patrimonio Metálico. UAM-CSIC, Madrid 2009.
 * 28) Krist, G. Metallrestaurierung-Metallkonservierung: Geschichte, Methode und Praxis, Vienna 2009.
 * 29) Safarzynski, S.; Weker, W.  Wprowadzenie do sztuki konserwacji metalu, Warsaw 2010.
 * 30) Schmidt-Ott, K. Das Plasma in der Metallkonservierung-Moeglichkeiten und Grenzen, Zurich 2010.(online)
 * 31) Bruecke, D. Die Konservierung pigmentierter Altbeschichtungen auf Stahlbauten, Saarbrücken 2011.
 * 32) Diaz Martinez, S.; Garcia Alonso, E. Tecnicas metodologicas applicadas a conservacion-restauracion del patrimonio metalico, Madrid 2011. (online)
 * 33) Barrio Martin, J.; Chamon Frenandez, J. Proyecto Dorados: tecnología, conservación y restauración de los metales dorados medievales, Madrid 2011.
 * 34) La técnica radiográafica en los metales históricos (English translation included), Madrid 2011. (online)
 * 35) Konzervování a restaurování kovů. Ochrana předmětů kulturního dědictví z kovů a jejich slitin, Brno 2011.
 * 36) Knaut, M.; Jeberien, A. (Hrsg.): Adel verpflichtet - Forschungen und Ergebnisse zur Konservierung und Restaurierung der barockzeitlichen Särge vom Schlossplatz Berlin-Mitte, Berlin 2012.
 * 37) Conservation of Metal Objects,National Research Institute of Cultural Heritage,Daejeon(S.Korea)2012.
 * 38) Schmutzler, B. Rettung vor dem Rost, Rahden 2012.
 * 39) Landesamt f. Denkmalpfl. u. Archäologie Sachsen-Anhalt (Hrsg.):Die Merseburger Fürstengruft Geschichte, Zeremoniell, Restaurierung, Halle 2013.
 * 40) Kuhn, H.; Emerling, E. Werke aus Kupfer, Bronze und Messing, Muenchen 2014.

Important older books

 * 1) Rathgen, F. Die Konservierung von Altertumsfunden, Berlin 1898 (chapter on metals conservation). (English edition online)
 * 2) Flinders Petrie, W.M. The Method and Aims in Archaeology, London 1904 (chapter on conservation) (online)
 * 3) Rosenberg, G. Antiquités en fer et en bronze : leur transformation dans la terre contenant de l'acide carbonique et des chlorures et leur conservation, Copenhagen 1917.
 * 4) Scott, A. The cleaning and restoration of museum exhibits (report upon investigation conducted at the British Museum, Department of Scientific and Industrial Research). London 1921.
 * 5) Scott, A. The cleaning and restoration of museum exhibits, 2d report. British Museum, Department of Scientific and Industrial Research. London 1923.
 * 6) Fink, C.G.; Eldridge, C.H. The restoration of ancient bronzes and other alloys, New York 1925.
 * 7) Galnbek, I.A. Ochistka i sokhranenie metallicheskikh predmetov drevnosti, Leningrad 1925 (first book dedicated to metals conservation/not only bronze and iron)
 * 8) Scott, A. The cleaning and restoration of museum exhibits, 3d report. British Museum, Department of Scientific and Industrial Research. London 1926.(Russian edition online)
 * 9) Nichols, H. W. Restoration of ancient bronzes and cure of malignant patina. Chicago 1930. (online)
 * 10) Lucas, A. Antiques: Their restoration and preservation. London 1932. (online)
 * 11) Plenderleith, H.J. The preservation of Antiquities, London 1934 (Chapter on metals conservation)
 * 12) Ocherki po metodike tehnologicheskog issledovaniya restavracii i konservacii drevnih metalicheskih izdeliy, Moscow 1935. (online)
 * 13) Farmakovskiy, M.V. Konservaciya i restavraciya muzeinih kollekciy, Moscow 1946 (chapter on metals conservation) (online)
 * 14) Plenderleith, H.J. The Conservation of Antiquities and Works of Art, London 1956 (chapter on metals conservation)
 * 15) France-Lanord, A.  La conservation des antiquites metalliques, Paris 1962.

Online magazines

 * BROMEC Bulletin of Research on Metal Conservation

Metals conservation blogs
1.Armas protohistóricas con magnetita, by Jesús Alonso López

2.Conservation of metals - by Catia Viegas-Wesolowska

3.Staffordshire Hoard Blog

Free software that can be used for metals conservation

 * 1) The Use of Expert Systems in Conservation
 * 2) The Modular Cleaning Program
 * 3) Download free conservators documentation software
 * 4) Freecorp-simple corrosion prediction software
 * 5) Online Cellular Automata based corrosion simulation

Metals conservation video files

 * 1) Conserving Bronze: The Lamp with Erotes from Vani
 * 2) Caring for Metals - Housekeeping for Historic Sites
 * 3) USS Monitor Engine Removed from Water
 * 4) Laser Cleaning of Bronze Eagle in Oak Park
 * 5) Re-Constructing Silver Objects from the Staffordshire Hoard
 * 6) Erik Risser Describes the Conservation of the Apollo Saettante at the Getty Villa
 * 7) CoinScubber - Cleaning Ancient Coins
 * 8) Cleaning an Outdoor Sculpture Part I
 * 9) Parlament Wien, Quadriga, Restaurierung, Bronze
 * 10) Dorure au mercure
 * 11) Repatination of a Bronze WWII Memorial Plaque
 * 12) how to care for bronze sculptures
 * 13) Restoring an Artifact at the SCCRRMM
 * 14) Clemson Conservation Center: H.L. Hunley submarine - Part 1/3
 * 15) NCPTT Iron Fence Repair - Cemetery Monument Conservation
 * 16) Restoration of the USS Monitor
 * 17) Apoxyomenos de Croacia 5
 * 18) Bronze Age Fibula
 * 19) Masterclass -silverplating
 * 20) Patina & corrosion surfaces on ancient bronzes
 * 21) Campanas medievales limpieza criogenica
 * 22) Restauro David Donatello
 * 23) Cruz Parroquial de la iglesia de Santa María de la Asunción de Estepa (Sevilla)
 * 24) Il nuovo intervento di restauro sui Bronzi di Riace
 * 25) Il restauro della base originale del Cinghiale in Firenze
 * 26) Restauración y conservación de los cañones de La Sabana
 * 27) Conservation of iron artefacts at Jamestown
 * 28) Cleaning the Staffordshire Hoard - K551 and K1775.