Volume 8, Issue 4 (3-2026)                   KCR 2026, 8(4): 52-68 | Back to browse issues page

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Hajjari E, Mortazavi M, Raeissi K, Hafezi Kahnamoei M. Chloride Ions Removal and Stabilization of Archaeological Irons: A Review of Methods, Efficiency, Limitations and Challenges. KCR 2026; 8 (4) :52-68
URL: http://journal.richt.ir/kcr/article-1-388-en.html
Chloride Ions Removal and Stabilization of Archaeological Irons: A Review of Methods, Efficiency, Limitations and Challenges
Elaheh Hajjari * , Mohammad Mortazavi , Keyvan Raeissi , Mohammad Hafezi Kahnamoei
& PhD student in Conservation of Historical and Cultural Objects, Art University of Isfahan, Iran.
Abstract:   (1647 Views)
The inherent instability of archaeological iron objects is due to contaminated with chloride ions from the burial environment, as well as being exposed to oxygen and high relative humidity. Therefore, the removal of chloride ions and the stabilization of active corrosion are essential steps to prevent further deterioration and to preserve these artefacts. Numerous scholars have investigated various methods for the dechlorination of archaeological irons. However, the complexity of the corrosion mechanisms, the varying condition under which artefacts were buried, the specific characteristic of each object, and the ethical principles of conservation and restoration confront conservation scientists with significant challenges. As a result, from the earliest research in this field to the present day, studies in the subjects are still ongoing. A meticulous review of the literature can lead to a better understanding of existing research findings and help identify aspects that more research is needed. The aim of this paper is to review, critique and examine each of the different chlorination methods, while also discussing their disadvantages and limitations. This review discuses different methods of chloride ions removal and stabilization of archaeological iron artefacts, including electrochemical techniques, immersion in alkaline aqueous solutions, application of subcritical fluids, hydrogen plasma, and biological treatment using bacteria. In addition, factors affecting the process before, during, and after dechlorination, as well as the specific challenges of treating large and composite objects are examined. Finally, by reviewing and comparing the studies conducted in this paper, it was found that there are still gaps in this regard, the analysis of which will ultimately lead to the application and optimization of appropriate dechlorination methods tailored to the specific characteristics of each object and its conservation conditions.
Keywords: Archaeological iron, Chloride, Corrosion, Dechlorination, Conservation treatment.
Full-Text [PDF 811 kb]   (318 Downloads)    
Type of Study: Research, Original, Regular | Subject: Archaeometry and authenticity assessment of museum objects and historical-cultural properties.
Accepted: 2026/03/3 | Published: 2026/03/3
References
1. Ahmed, S. M. S. (2011). Conservation methods of iron artifacts recovered from the marine environment. Doctoral dissertation, National Technical University of Athens, School of Chemical Engineering, Department of Material Science.
2. Albini, M., Comensoli, L., Brambilla, L., Domon Beuret, E., Kooli, W., Mathys, L., Letardi, P., & Joseph, E. (2015). Innovative biological approaches for metal conservation. Materials and Corrosion 67. doi: 10.1002/maco.201408168 .
3. Andersen, Lars Brock (2006), 'Desalination of archaeological iron artefacts after D.C. Mode Hydrogen Plasma Treatment', Archaeological Metal Finds - From Excavation to Exhibition (Mannheim, Germany).
4. Askey, A., Lyon, S., Thompson, G., Johnson, J., Wood, G., Cooke, M & Sate, P. (1993). The corrosion of iron and zinc by atmospheric hydrogen chloride. Corrosion Science, 34, 233–247.
5. Batis, G., Zacharopoulou, A., Zacharopoulou, E., Siova, H., Argyropoulos, V. (2015). Dechlorination of large marine iron artifacts using a novel technique involving impressed current. Anti-Corrosion Methods and Materials, 62, 259–269.
6. Coelho, J. C., Oliveira, C. M., Carvalho, M. D., Fonseca, I.T.E. (2014). The efficiency of electrochemical methods for the removal of chloride ions from iron marine archaeological objects: A comparative study. Materials and Corrosion. 65, 38–44.
7. Comensoli, L., Maillard, J., Albini, M., Sandoz, F., Junier, P., & Joseph, E. (2017). Use of bacteria to stabilize archaeological iron. Applied and Environmental Microbiology, 83(9), e03478–16.
8. Cornell, R. M., & Giovanoli, R. (1988). Acid dissolution of akaganeite and lepidocrocite: The effect on crystal morphology. Clays and Clay Minerals, 36(5), 385–390.
9. Cuvillier, L., Passaretti, A., Raimon, A., Dupuy, V., Guilminot, E., & Joseph, E. (2022). Exploiting biologically synthetized chelators in conservation: Gel-based bio-cleaning of corroded iron heritage objects. In Proceedings of the Metal 2022 Proceedings of the Interim Meeting of the ICOM-CC Metals Working Group, Helsinki, Finland, 5–9 September 2022; Mardikian, P., Näsänen, L., Arponen, A., Eds.; International Councils of Museums—Committee for Conservation: Helsinki, Finland, 2022; pp. 25–34.
10. Cuvillier, L., Passaretti, A., Guilminot, E., & Joseph, E. (2023). Testing of the siderophore deferoxamine amended in hydrogels for the cleaning of iron corrosion. The European Physical Journal Plus, 138(6), 569. https://doi.org/10.1140/epjp/s13360-023-04159-y.
11. Dalard, F., Gourbeyre, Y., & Degrigny, C. (2002). Chloride removal from archaeological cast iron by pulsating current. Studies in Conservation, 47, 117–121.
12. Daniel, D., Holland, L., & Pascoe, W. (1979). Gas plasma reactions for the conservation of antiquities. Studies in Conservation, 24, 1–6.
13. Degrigny, C., & Spiteri, L. (2004). Electrochemical monitoring of marine iron artifacts during their storage and stabilization in alkaline solutions. Proceedings of Metal, National Museum of Australia, Canberra, ACT, 4–8 October 2004, Published by the National Museum of Australia. p. 315.
14. Degrigny, C., Langh, R.., Joosten, I., & Ankersmit, B., (2007). Use of electrochemical techniques in metal conservation, interim meeting of the ICOM-CC Metal WG, Amsterdam, ed. Christian Degrigny, Langh, R., Joosten, I.,Ankersmitimprime, B., Amsterdam: Rijksmuseum Amsterdam, Metal 2007, p. 47-54.
15. Dillmann, P., Béranger, G., Piccardo, P., & Mathiesen, H. (2007). Corrosion of metallic heritage artefacts: Investigation, conservation and prediction of long-term behaviour (EFC 48). Woodhead Publishing.
16. Drews, M., González-Pereyra, N. and Cook, D. (2014). The transformation of iron oxides, oxyhydroxides and corrosion products by subcritical water treatment. In: Hyslop, E., et al. eds. Metal 2013: Interim Meeting of the ICOM-CC Metal Working Group. Edinburgh, 16-20 September 2013. Edinburgh: Historic Scotland and International Council of Museums, pp. 111-118.
17. Doménech-Carbó, A., (2010). Electrochemistry for conservation science, J. Solid state electrochem., 14: pp. 349–351.
18. Fontaine, C., Lemoine, S., Pelé-Meziani, C., & Guilminot, E. (2022). The use of gels in localized dechlorination treatments of metallic cultural heritage objects. Heritage Science, 10(1), 117. https://doi.org/10.1186/s40494-022-00752-z.
19. Frydendahl, J., Andersen, L. B., Wiinblad, T., Carré, C., Dillmann, P., Neff, D., & Matthiesen, H. (2022). A simple treatment system for the deaerated desalination of archaeological iron. Poster presented at Metal 2022: 10th Interim Meeting of the ICOM-CC Metals Working Group, Helsinki, Finland, 5–9 September 2022.
20. Gilberg, M. R. (1985). The storage of archaeological iron under deoxygenated conditions. ICOM Committee for Conservation Metals Working Group Newsletter, 1, 3.
21. Giraud, T., Gomez, A., Lemoine, S., Pelé-Meziani, C., Raimon, A., Guilminot, E. (2021). Use of gels for the cleaning of archaeological metals: Case study of silver-plated copper alloy coins. Journal of Cultural Heritage, 52, 73–83.
22. Greiff, S., & Bach, D. (2000). Eisenkorrosion und natriumsulfitentsalzung: Theorie und Praxis. Arbeitsblätter für Restauratoren, 33(2), 319–339.
23. Graedel, T. E., & Frankenthal, R. P. (1990). Corrosion mechanisms for iron and low alloy steels exposed to the atmosphere. Journal of the Electrochemical Society, 137, 2385–2394
24. González-Pereyra, N., Näsänen, L., & Cretté, S. (2013). From rivets to composites – ten years of subcritical research. In Ewan H, et al. (Eds.), Interim meeting of the ICOM-CC Metal Working Group, (Edinburgh, United Kingdom: Historic Scotland), 201-06.
25. González, K. S., & Salvato, M. (2019). Pictures speak for themselves: Case studies proving the significance and affordability of X-ray for archaeological collections. In New life for archaeological collections, In New Life for Archaeological Collections, edited by Rebecca Allen and Ben Ford. pp. 226-244. Society for Historical Archaeology and the University of Nebraska Press: Lincoln, Nebraska.
26. Guilminot, E., Neff, D., Rémazeilles, C., Reguer, S., Kergourlay, F., Pelé, C., Dillmann, P., Refait, P., Nicot, F., Mielcarek, F., Huet, N., & Rebière, J. (2012). Influence of crucial parameters on the dechlorination treatments of ferrous objects from seawater. Studies in Conservation, 57(4), 227–36.
27. Guilminot, E. (2023). The use of hydrogels in the treatment of metal cultural heritage objects. Gels, 9(3), 191. https://doi.org/10.3390/gels9030191.
28. Hamilton, D. (1997). Basic methods of conserving underwater archaeological material culture. Nautical Archaeology Program, Department of Anthropology, Texas A&M University.
29. Hamilton, D. L. (1999). Methods of conserving archaeological material from underwater sites: Metal conservation, preliminary steps (pp. 38–47). http://nautarch.tamu.edu/class/anth605/File10b.htm#Sodium
30. James, S., & Joseph, E. (2021). Microbial-driven stabilisation of archaeological iron artefacts. Corrosion and Materials Degradation, 2(2), 274–292. https://doi.org/10.3390/cmd2020015.
31. Keene, S., & Orton, C. (1985). Stability of treated archaeological iron: An assessment. Studies in Conservation, 30: 136–142.
32. Kergourlay, F., Guilminot, E., Neff, D., Rémazeilles, C., Reguer, S., Refait, P., Mirambet, F., Foy, E., & Dillmann, P. (2010). Influence of corrosion products nature on dechlorination treatment: Case of wrought iron archaeological ingots stored two years in air before NaOH treatment. Corrosion Engineering, Science and Technology, 45(5), 407–413.
33. Kergourlay, F., Rémazeilles, C., Neff, D., Foy, E., Conforto, E., Guilminot, E., Reguer, S., Dillmann, P., Nicot, F., Mielcarek, F., Rebiere, J., & Refait, P. (2011). Mechanisms of the dechlorination of iron archaeological artefacts extracted from seawater. Corrosion Science, 53, 2474–2483.
34. Kergourlay, F., Réguer, S., Neff, D., Foy, E., Picca, F. E., Saheb, M., Hustache, S., Mirambet, F., & Dillmann, P. (2018). Stabilization treatment of cultural heritage artefacts: In situ monitoring of marine iron objects dechlorinated in alkali solution. Corrosion Science, 132, 21–34. https://doi.org/10.1016/j.corsci.2017.12.028
35. Krcma, F., Raskova, Z., Klima, M., & Kousal, J. (2007). Characterization of plasma chemical treatment of archaeological artefacts. Treatment of Archaeological Artifact, http://www.phys.tue.nl/FLTPD/poster/krcma1.pdf.
36. Matthiesen, H., Frydendahl, J., Andersen, L. B., Wiinblad, T., Carré, C., Dillmann, P., & Neff, D. (2022). Natural conservation of archaeological iron. Poster presented at Metal 2022: 10th Interim Meeting of the ICOM-CC Metals Working Group, Helsinki, 5–9 September 2022.
37. Memet, J. (2008). Conservation of underwater cultural heritage: Characteristics and new technologies. Museum International, No. 240, Vol. 60, No. 4.
38. Näsänen, L. M. E., González-Pereyra, N. G., Crettéa, S. A., & DeViviés, P. (2013). The applicability of subcritical fluids to the conservation of actively corroding iron artifacts of cultural significance. The Journal of Supercritical Fluids, 79, 289–298.
39. Nordgren, E., Goncalves, P., Shindelholtz, E., Brossia, C. S., & Yunovich, M. (2007). Use of electrochemical techniques in metal conservation. In Metal 07, Book 3: Interim Meeting of the ICOM-CC Metal WG. Amsterdam, 17–21 September 2007; Degrigny,C.,VanLangh,R.,Joosten,I.,Ankersmit,B.,Eds.; Rijksmuseum: Amsterdam.
40. Nordgren, E. (2017). The effect of metallurgical structure on the chloride-induced corrosion of archaeological wrought iron. Doctoral dissertation, Cardiff University.
41. North, N. A., & Pearson, C. (1975). Alkaline sulfite reduction treatment of marine iron. In ICOM Committee for Conservation, 4th Triennial Meeting, Venice, 13-18 October. Paris: ICOM.
42. North, N., & Pearson, C. (1977). Thermal decomposition of FeOCl and marine cast iron corrosion products. Studies in Conservation 22, 146–157.
43. North, N. A., & MacLeod, I. D. (1987). Corrosion of metals. In Pearson, C. ed, Conservation of marine archaeological objects. London: Butterworths, pp. 68–98.
44. Ouyang, W., Cao, X., & Wang, N. (2009). A mathematical model for electrochemical chloride removal from marine cast iron artifacts. Acta Metal, Sinica Direct, Vol.22, No.2, pp. 91-99.
45. Parra, R., Covelo, A., Ramirez, R. J., Tejeda, A., Ortega, A., & Hernandez, M. (2017). Characterization of superficial modification of ferrous rusted substrates subjected to dechlorination-electrochemical process. Journal of Adhesion Science and Technology, 32(12), 1341–1358.
46. Passaretti, A., Cuvillier, L., Sciutto, G., Guilminot, E., & Joseph, E. (2021). Biologically derived gels for the cleaning of historical and artistic metal heritage. Applied Sciences, 11(8), 3405.
47. Patscheider, J., & Veprek, S. (1986). Application of low-pressure hydrogen plasma to the conservation of ancient iron artifacts. Studies in Conservation, 31, pp. 29-37.
48. Petrasz, P., Zhioua, S., James, S., Bindschedler, S., Junier, P., & Joseph, E. (2024). Green alternatives for archaeological iron stabilization. Studies in Conservation, 69(sup1), 270–280.
49. Pienimäki, A. (2022). Commercially available vacuum chambers as an alternative in the deoxygenated desalination treatment of archaeological iron. Kiruna Centre for Conservation of Cultural Property, Kiruna, Sweden.
50. Pienimäki, A. (2023). Desalination of archaeological iron objects in vacuum. Master’s thesis, University of Gothenburg. Department of Conservation
51. Pollard, A., Batt, C., Stern, B., & Young, S. (2007). Analytical chemistry in archaeology. Cambridge University Press, New York, p.6.
52. Reguer, S., Dillmann, P., Mirambet, F., & Bellot-Gurlet, L. (2005). Local and structural characterization of chlorinated phases formed on ferrous archaeological artefacts by μ-XRD and μ-XANES. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 240(1), 500–04
53. Reguer, S., Dillmann, P., & Mirambet, F. (2007a). Buried iron archaeological artefacts: Corrosion mechanisms related to the presence of Cl-containing phases. Corrosion Science, 49 (6), 2726–44.
54. Reguer, S., Neff, D., Bellot-Gurlet, L., & Dillmann, P. (2007b). Deterioration of iron archaeological artefacts: Micro-Raman investigation on Cl-containing corrosion products. Journal of Raman Spectroscopy, 38(4), pp. 389-397.
55. Rimmer, M. (2010). Investigating the treatment of chloride-infested archaeological iron objects. PhD Thesis, Cardiff University.
56. Rimmer, M., Watkinson, D., & Wang, Q. (2013). The impact of chloride desalination on the corrosion rate of archaeological iron. Studies in Conservation, 58(4), p. 326-337.
57. Rodgers, B. (2004). The archaeologist’s manual for conservation, A guide to non-toxic, minimal intervention artifact stabilization, Springer Science, Birkhäuser, pp.83-91
58. Russo, R E., Zamponi, S., Conti, P., Piloni, R., Pierigè, M. I., Faustoferri, A., Fattobene, M., & Berrettoni, M. (2023). Dechlorination of iron artefacts: a novel approach. Materials letters, 338, 133968.
59. Sansonetti, A., Bertasa, M., Canevali, C., Rabbolini, A., Anzani, M., & Scalarone, D. (2020). A review in using agar gels for cleaning art surfaces. Journal of Cultural Heritage, 44, 285–296.
60. Schaefer, K., & Mills, D. J. (2017). The application of organic coatings in conservation of archaeological objects excavated from the sea. Progress in Organic Coatings, 102, 99–106.
61. Schmidt-Ott, K., & Boissonnas, V. (2002). Low-pressure hydrogen plasma: An assessment of its application on archaeological iron. Studies in Conservation 47, pp. 8187.
62. Schmidt-Ott, K. (2004). Plasma-reduction: Its potential for use in the conservation of metals. Metal 04: Proceedings of the International Conference on Metals Conservation. Canberra. Australia. 4-8 October 2004. ed. J. Ashton and D. Hallam. Canberra, National Museum of Australia: 235-246.
63. Schmidt-Ott, K., & Oswald, N. (2006). Alkaline sulfite desalination: Tips and tricks. VDR conference handbook. "Archaeological Metal Finds - From Excavation to Exhibition". October ll-13th 2006, Mannheim, Germany: 17.
64. Schmutzler, B., & Ebinger-Rist, N. (2008). The conservation of iron objects in archaeological preservation – Application and further development of alkaline sulphite method for conservation of large quantities of iron finds. Materials and Corrosion 59(3): 248-253.
65. Scott, D. A., & Eggert, G. (2009). Iron and steel in art. London, Archetype.
66. Selwyn, L. S., Sirois, P. J., & Argyropoulos, V. (1999). The corrosion of excavated archaeological iron with details on weeping and akaganeite. Studies in Conservation 44: 217–232.
67. Selwyn, L. S. (2004). Overview of archaeological iron: The corrosion problem, key factors affecting treatment, and gaps in current knowledge. Metal 04: Proceedings of the International Conference on Metals Conservation. Canberra. Australia. October 2004. ed. J. Ashton and D. Hallam. Canberra, National Museum of Australia: 294-306.
68. Selwyn, L. S., & Argyropoulos, V. (2005). Removal of chloride and iron ions from archaeological wrought iron with sodium hydroxide and ethylenediamine solutions. Studies in Conservation 50(21: 81–100.
69. Siova, E., Argyropoulos, V., & Batis, G. (2023). An investigation of electrochemical dechlorination of wrought iron specimens from the marine environment. Heritage, 6(1), 587–599.
70. Singer, S. (1998). Shipwrecks of Florida: A comprehensive listing, Edn. 2, Pineapple press, USA, p.335.
71. Stambolov, T. (1985). The corrosion and conservation of metallic antiquities and works of art. Amsterdam.
72. Turgoose, S. (1982a). Post-excavation changes in iron antiquities. Studies in Conservation 27: 97–101.
73. Turgoose, S. (1982b). The nature of surviving iron objects. Conservation of Iron: Maritime Monographs and Reports No. 53. ed. R. W. Clarke and S. M. Blackshaw. London, National Maritime Museum: 1-7.
74. Tylecote, R. F., & Black, J. W. B. (1980). The effect of hydrogen reduction on the properties of ferrous materials. Studies in Conservation 25: 87-96.
75. Wang, Q. (2007a). An investigation of deterioration of archaeological iron. Studies in Conservation 52:125-134.
76. Wang, Q., Dove, S., Shearman, F., & Smirniou, M. (2008). Evaluation of methods of chloride ion concentration determination and effectiveness of desalination treatments using sodium hydroxide and alkaline sulphite solutions. The Conservator 31.
77. Watkinson, D. (1996). Chloride extraction from archaeological iron: comparative treatment efficiencies. Archaeological Conservation and its Consequences: Preprints of the Contribution to the Copenhagen Congress. 26-30 August 1996. ed. A. Roy and P. Smith. London, International Institute for Conservation: 208-212.
78. Watkinson, D., & Lewis, M. R. T. (2005a). The role of β-FeOOH in the corrosion of archaeological iron. Materials Issues in Art and Archaeology VII. ed. P. B. Vandiver, J. L. Mass and A. Murray. Warrendale, PA, Materials Research Society of America Symposium: 103-114.
79. Watkinson, D., & Lewis, M. R. T. (2005b). Desiccated storage of chloride-contaminated archaeological iron objects. Studies in Conservation, 50: 241–252.
80. Watkinson, D., & Al-Zahrani, A. (2008). Towards quantified assessment of aqueous chloride extraction methods for archaeological iron: De-oxygenated treatment environments. The Conservator 31: 75–86.
81. Xu, C., & Wang, J. (2003). Investigation of the chemical and electrochemical behaviour of mass transfer at an archaeological bronze/soil interface, Anti-Corrosion Methods and Materials 50 (5): 326-333.
82. Yadav, O. (2009). Conservation of indoor archaeological objects. Ancient Nepal, P.9.
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