rust converter
{{Short description|Type of useful chemical solution}}
Rust converters are chemical solutions or primers that can be applied directly to an iron or iron alloy surface to convert iron oxides (rust) into a protective chemical barrier. These compounds interact with iron oxides, especially iron(III) oxide, converting them into an adherent black layer (black oxide) that is more resistant to moisture and protects the surface from further corrosion. They are sometimes referred to as "rust remover" or "rust killer".
Typical ingredients
Commercial rust converters are water-based and contain two primary active ingredients: tannic acid{{cite web|title=Rust Conversion Mechanism|url=http://corrosion-doctors.org/MetalCoatings/rust-converter.htm}} and an organic polymer. Tannic acid chemically converts the reddish iron oxides into bluish-black ferric tannate, a more stable material.{{cite web|url=https://www.canada.ca/en/conservation-institute/services/conservation-preservation-publications/canadian-conservation-institute-notes/tannic-acid-rusted-iron-artifacts.html|title=Tannic Acid Coating for Rusted Iron Artifacts, formerly published under the title Tannic Acid Treatment – Canadian Conservation Institute (CCI) Notes 9/5 - Canada.ca|website=www.canada.ca|date=14 September 2017}} The second active ingredient is an organic solvent such as 2-butoxyethanol (ethylene glycol monobutyl ether, trade name butyl cellosolve) that acts as a wetting agent and provides a protective primer layer in conjunction with an organic polymer emulsion.{{citation needed|date=October 2012}}
Some rust converters may contain additional acids to speed up the chemical reaction by lowering the pH of the solution. A common example is phosphoric acid, which additionally converts some iron oxide into an inert layer of ferric phosphate.{{cite web|last=Maltby|first=Susan L.|title=Rust Converters|url=http://www.alan.net/prgshoptips/rustconv.html|publisher=Old-House Journal|accessdate=24 June 2012|date=November 1998|url-status=dead|archiveurl=https://archive.today/20010508064152/http://www.alan.net/prgshoptips/rustconv.html|archivedate=8 May 2001}} Most of the rust converters contain special additives.[https://www.schwegmannnet.de/pdf/broschueren/lack/en/corrosion_protection_en.pdf SchwegmannNet.de: Corrosion Protection of Metallic Surfaces]. Retrieved 29 October 2019. They support the rust transformation and improve the wetting of the surface.
Uses
Rust converter is usually applied to objects that are difficult to sand blast, such as vehicles, trailers, fences, iron railings, sheet metal, and the outside of storage tanks. It may also be used to restore and preserve iron-based items of historical importance.{{cite web|url=https://www.ncptt.nps.gov/blog/materials-research-program-begins-rust-convertor-study/|archive-url=https://web.archive.org/web/20130517132854/http://ncptt.nps.gov/blog/materials-research-program-begins-rust-convertor-study/|url-status=dead|archive-date=May 17, 2013|title=NCPTT - Materials Research Program Begins Rust Converter Study|website=www.ncptt.nps.gov}}
See also
References
{{Reflist}}
External links
- [http://www.mnhs.org/preserve/conservation/reports/iron_bells.pdf "The Conservation of Two Cast Iron Bells at the Lac Qui Parle Mission Historic Site" (PDF, 131 kB)]