Conservation and restoration of iron and steel objects

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An pillar, slightly fluted, with some ornamentation at its top. It is black, slightly weathered to a dark brown near the base. It is around 7 meters (22 feet) tall. It stands upon a raised circular base of stone, and is surrounded by a short, square fence.
The iron pillar of Delhi is an example of the iron extraction and processing methodologies of India. It has withstood corrosion for the last 1600 years.

The conservation and restoration of iron and steel objects is an activity dedicated to the preservation and protection of objects of historical and personal value made from iron or steel. When applied to cultural heritage this activity is generally undertaken by a conservator-restorer.

Historically, objects made from iron or steel were created for religious, artistic, technical, military and domestic uses. The act of conservation and restoration strives to prevent and slow the deterioration of the object as well as protecting the object for future use. The prevention and removal of surface dirt and corrosion products are the primary concerns of conservator-restorers when dealing with iron or steel objects, including nickel-iron meteorites.


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 objects 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.

Identification of metals and alloys[edit]

Identification of corrosion processes and products[edit]

  • 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[edit]

  • Simple methods - visual examination, spot tests, specific gravity
  • Scientific methods - xrf, chromatography

Identification of technology used to produce objects[edit]

Decision making[edit]

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.


Painted objects must be cleaned with polar/non polar solvents or solvent mixtures.

Structural consolidation[edit]

Screws, rivets, gluing, soldering, welding may be used to conserve the structure.

Protective coatings[edit]

  • Clearcoats - Paraloid B-72 - Permalac - Ormocer
  • Waxes - Renaissance Wax - Cosmolloid 80 H - Dinitrol 4010 - Poligen ES 91009
  • Oils - Ballistol - WD-40 - 8 parts white spirit/2 parts fish oil
  • Combinations - basecoat Paraloid B 72 + topcoat Renaissance wax etc.

Archaeology objects[edit]


Only mechanical cleaning can be used(scalpel,micromotor and steel brushes and abrasive discs,microsandblasting unit,ultrasonic chisel).

Structural consolidation[edit]

Gluing only can be used,reversible types are the Best. Glass fibre reinforcments can be used too.


  • alkaline sulphite treatment[1]
  • NaOH/ethylenediamine treatment[2]
  • low-temperature hydrogen plasma treatment[3]
  • subcritical fluids treatment (40 atm., 180 C, 0,5% NaOH)[4]
  • cathodic polarisation[5]

Protective coatings[edit]

  • Clearcoats - Paraloid B-72 - Paraloid B-44 - Permalac - Ormocer
  • Waxes - Renaissance Wax - Cosmolloid 80 H - Dinitrol 4010 - Poligen ES 91 009
  • Combinations - basecoat Paraloid B 72 + topcoat Renaissance wax etc.

Preventive conservation[edit]

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 nitrogen or argon. Iron objects with active corrosion up to 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) [54]

See also[edit]

Further reading[edit]

  • Selwyn, L. Metals and Corrosion-A Handbook for Conservation Professional, Ottawa 2004.
  • Jain Kamal K., Narain Shyam, Iron artifacts history, metallurgy, corrosion and conservation, Delhi 2009.
  • Scott; D.A.; Eggert, G. Iron and Steel in Art - Corrosion, Colorants, Conservation, London 2009.
  • Scott,D.A. Metallography and Microstructure of Ancient and Historic Metals, Santa Monica 1991.
  • Scott, D.A. Ancient and Historic Metals-Conservation and Scientific Research, Santa Monica 1994.
  • Dillman, P.; Beranger, G.; Piccardo, P.; Matthiesen, H. Corrosion of metallic heritage artefacts-Investigation,Conservation and Prediction of long term behaviour, Cambridge 2007.
  • Cronyn, J.M. The Elements of Archaeological Conservation, London 1990.
  • La Niece,S.; Craddock, P. Metal Plating and Patination: Cultural, Technical and Historical Developments, Boston 1993.
  • Hollner, S., Mirambet, F., Texier, A., Rocca, E., Steinmetz, J. 2007. Development of new non-toxic corrosion inhibitors for cultural property made of iron and copper alloys. Article: V. Argyropoulos, A. Hein, M. Abdel Harith (Eds) Strategies for Saving our Cultural Heritage. Proceedings of the International Conference on Conservation Strategies for Saving Indoor Metallic Collections, Cairo. p. 156-161. Athens: Technological Educational Institute of Athens
  • Gilberg, M. R.; Seeley, N. J.: The alkaline sodium sulphite reduction process for archaeological iron: a closer look, Studies in Conservation 27, 1982., p. 180.-184.
  • Турищева Р.А., Рябинков А.Г. Применение современных материалов для консервации предметов из черных металлов в музейной коллекции // Реставрация памятников истории и культуры / ГБЛ. Информкультура / Экспресс-информация. - М., 1987. Вып. 3. - С. 1-6. .
  • Costain, C. G.: Evaluation of storage solutions for archaeological iron, Journal of the Canadian Association for Conservation 25, 2000., p. 11.-20.
  • Greiff, S.; Bach, D.: Eisenkorrosion und Natriumsulfitentsalzung: Theorie und Praxis, Arbeitsblätter für Restauratoren, Gruppe 1, 2000., p. 319.-339.
  • Watkinson, D.: Chloride extraction from archaeological iron: comparative treatment efficiencies, Archaeological conservation & it's consequences: Preprints of the contributions of the Copenhagen Congress 1996, International Institute for Conservation, London, 1996., p. 208.-212.
  • Keene, S.; Orton, C.: Stability of treated archaeological iron: an assessment, Studies in Conservation 30, 1985., p. 136.-142.
  • North, N. A.; Pearson, C.: Alkaline sulfite reduction treatment of marine iron, ICOM Committee for Conservation, 4th triennial Meeting, Venice, 13.-18. listopada 1975., reizdanje: Paris: International Council of Museums, 75/13/3, p. 1.-14.
  • Turgoose, S.: Post-excavation changes in iron antiquities, Studies in Conservation 27, 1982., p. 97.-101.
  • Blackney, K. 2010.Painting Historic Ironwork. Cathedral Communications Ltd.[6]
  • Mardikian, P.; Gonzalez, N. G.; Drews, M. J.; Nassanen, L.; ur. Eggert, G.; Schmutzler, B.: The use of subcritical alkaline solutions for the stabilization of archaeological iron artifacts, Archaeological Iron Conservation Colloquium State Academy of Art & Design, Stuttgart, 24.-26. 06. 2010., p. 59.-62.
  • Neff, D.; Réguer, S.; Bellot-Gurlet, L.; Dillman, P.; Bertholon, R.: Structural characterization of corrosion products on archaeological iron: an integrated analytical approach to establish corrosion forms, Journal of Raman Spectroscopy, 35, 2004., p. 739.-745.
  • Selwyn, L.; McKinnon, W. R.; Argyropoulos, V.: Models for Chloride ion Diffusion in Archaeological Iron, Studies in Conservation, 46, 2001., p. 109.-120.
  • MacLeod, I. D.; ur. Roy, A.; Smith, P.: In-situ conservation of cannon and anchors on shipwreck sites, Conservation of Archaeological Sites and its Consequences, IIC, London, 1996., p. 111.-115.
  • Hallam, D., Thurrowgood, D., Otieno-Alego, V. and Creagh,D. 2004. An EIS Method for assessing thin oil films used in museums.Metal 04: Proceedings of the International Conference on Metals Conservation, Canberra, Australia,4–8 October 2004. p. 388-399. Canberra: National Museum
  • MacLeod I. D.; Cook, D.; Schindelholz, E.: Corrosion and conservation of the American civil war ironclad USS Monitor (1862), Preprints for ICOM-CC Triennial Meeting, New Delhi, 09. 2008., p. 279.-285.
  • Schmuecker, E.: Historic iron: surface stabilisation and appearance, MA thesis, Royal College of Art and Victoria and Albert Museum, London, 2004.
  • Lemos, M.; Tissot, I.; Tissot, M.; Pedroso, P.; Silvestre, P.; ur. Degrigny, C.; Van Langh, R.; Ankersmit, B.; Joosten, I.: Conservation of a Portuguese 15th-century iron cannon: the advantages of dry-ice blasting methodology, poster presented at METAL07, Proceedings of the ICOM-CC Metal WG interim meeting, Rijksmuseum, Amsterdam, IV. , 2007., p. 53.
  • Davey, A. 2007. INFORM The Maintenance of Iron Gates and Railings. Edinburgh: Historic Scotland Technical Conservation, Research and Education Group.
  • Turner, R.; ur. Moody, H.: Abrasive cleaning: an overview, Selected Papers from a Series of Conferences organized by the Metal Section of UKIC 1999-2000, Metals Section Press of the United Kingdom Institute for Conservation, London, 2002., p. 31.-33.
  • Wilson, Lyn; Davey, Ali; Mitchell, David S.; Davidson, Alan: Traditional Architectural Ironwork : Scientific Approaches to Determining Best Conservation Practice and the Bute Canopy Case Study in Metal 2010, Proceedings of the Interim Meeting of the ICOM-CC Metal WG, Charleston, 2010.
  • Degrigny, C. 2010. Use of artificial metal coupons to test new protection systems on cultural heritage objects: manufacturing and validation.Corrosion Engineering, Science and Technology 45(5), p. 367-374
  • Wilson, Lyn; Mitchell, David S.;, Davey, Ali; Pritchard, D., ur. Mardikian, P.; Chemello, C.: Digital Documentation of Historic Ferrous Metal Structures: 3D Laser Scanning as a Conservation Tool, Metal 2010, Proceedings of the Interim Meeting of the ICOM-CC Metal WG, Charleston, South Carolina, 11.-15. 10. 2010.
  • Fryer, Emily; Pullen, Derek; Greenfield, David; ur. Mardikian, P.; Chemello, C.; Watters, C., Hull, P.: Saving Your Spangles: The Conservation and Care of Galvanised Steel Sculptures, Metal 2010, Proceedings of the Interim Meeting of the ICOM-CC Metal WG, Clemson University, Charleston, South Carolina, 11.-15. 10. 2010.
  • Barker, D. 2010.Restoration of Antique Wrought Ironwork.Cathedral Communications Ltd.[7]
  • Eggert,G.;Kuhn,C. et al. Another Base, Another Solvent? Desalinating Iron Finds with Tetramethylammonium Hydroxide Solutions, e-Preservation Science 8, Ljubljana 2011., str. 81-85
  • Eggert,G.;Kuhn,C. Keep cool? Deep-freeze storage of archaeological iron, Metal 2010, Clemson University Charleston (SC) 2011, p. 32-38
  • Eggert,G.;Schmutzler,B. Lässt sich die Konservierung von Eisenfunden `auf Standard´ bringen?

Article: U. Peltz und O. Zorn (Hrsg.): KulturGUTerhalten. Standards in der Restaurierungs- wissenschaft und Denkmalpflege. Mainz 2009, p. 91-95

  • J C Gillies, I Seyb:La Fee aux Fleurs - investigation and conservation of a 19th-century outdoor cast iron sculpture, METAL 2013., Edinburgh 2013., Conference proceedings
  • J Church, A Muto, M Striegel:Comparative study of rust converters for historic outdoor metalwork, METAL 2013., Edinburgh 2013., Conference proceedings
  • M. Bayle, P. de Viviés, J.-B. Memet, P. Dillmann, D. Neff Impact of the Subcritical Stabilisation Process on Corrosion Layers of Iron Artefacts from Different Archaeological Corrosion Contexts, METAL 2016.,New Delhi 2017.,Conference proceedings
  • A. Pandya, J.K. Singh, D.D.N. Singh An Eco-Friendly Method to Stabilize Unstable Rusts, METAL 2016.,New Delhi 2017.,Conference proceedings
  • A.B. Paterakis, M. Mariano Oxygen Absorption for the Protection of Archaeological Iron: Improving Maintenance,METAL 2016.,New Delhi 2017.,Conference proceedings
  • B. Ramírez Barat, T. Palomar, B. García, D. de la Fuente, E. Cano .Composition and Protective Properties of Weathering Steel Artificial Patinas for the Conservation of Contemporary Outdoor Sculpture, METAL 2016.,New Delhi 2017.,Conference proceedings


  1. ^ Gilberg, M.; Seeley, N. The Alkaline Sodium Sulphite Reduction Process for Archaeological Iron: A Closer Look, Studies in Conservation, London 1982.
  2. ^ accessed May 23, 2012
  3. ^ Sjogren, A.; Mathiesen, T.; van Lanschot, J.' Turgoose, S., and Hawkins. C 'Rapid low-temperature hydrogen plasma treatment of archaeological iron'. Zeitschrift für Schweizerische Archäologie und Kunstgeschichte 54 (1997) 34-40.
  4. ^ "The application of subcritical fluids for the stabilization of marine archaeological iron". Retrieved November 28, 2014.
  5. ^ "Maney Online - Maney Publishing". Retrieved November 28, 2014.
  6. ^ "Painting Historic Ironwork".
  7. ^ "Restoration of Antique Wrought Ironwork".

External links[edit]