An overview of modern ways of cleaning from rust and preservation of iron historical artefacts

Abstract

This overview focused on the recent advances in rust cleaning and conservation of iron-based historical artefacts. Archaeological iron artefacts undergo various forms of corrosion, including soil and atmospheric. In general the main corrosion products are goethite α-FeO​​(OH), acaganeite β-FeO (OH), lepidocrocite γ-FeO (OH), magnetite Fe3O4, siderite FeCO3, vivanite Fe3(PO4)2 ∙ 8H2O, etc. A number factors contribute to the process corrosion, but Cl- anion embedded in the crystal lattice of acagenite is crucial. It has been considered corrosion product removers from the artefact surface, and found out that all of them should contain inhibitors slowing down the interaction of the artefact iron core with acids. Organic acids, in particular citric, maleic and acetic acids are considered to be non-aggressive and environmental-friendly. After removing corrosion product layer, iron historical heritages are affected by atmospheric corrosion thus stabilizing substances and protective coatings must be applied. The most common protectors are tannin-iron complex compounds, which provide an anti-corrosion coatings and prevent further destruction of artefacts. Preservation of iron-based historical artefacts with synthetic polymer waxes, resins and synthetic polymers is thought to be promising.