BPG Chelating Agents

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Book and Paper Group Wiki > Book Conservation Wiki > Chelating Agents

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Wiki Contributors: Jennifer Evers, Valeria Orlandini, Theresa J. Smith, please add your name here

Copyright 2025. The AIC Wiki is a publication of the American Institute for Conservation (AIC). It is published as a convenience for the members of AIC. Publication does not endorse nor recommend any treatments, methods, or techniques described herein. Information on researching with and citing the wiki can be found on the Reference and Bibliography Protocols page.

Cite this page:

American Institute for Conservation (AIC). "BPG Chelating Agents." AIC Wiki. November 18, 2025. https://www.conservation-wiki.com/wiki/BPG_Chelating_Agents.

Bibliography

Overview

Adler, Susan, and Linda Eaton. 1995. "Chelating Agents in Wet Cleaning Systems." AIC Textile Specialty Group Postprints 5: 69-78. Washington, DC: AIC.

Ahn, Kyujin, Andreas Hartl, Christa Hofmann, Ute Henniges and Antje Potthast. 2014. "Investigation of the Stabilization of Verdigris-containing Rag Paper by Wet Chemical Treatments." Heritage Science 2: 1-14.

Blank, M.G. and Svetlana A. Dobrusina. 1984. "Raising of the Book-Paper Longevity by Means of Chelates and Ca-Chelate Compound." In ICOM-CC 7th Triennial Meeting, Copenhagen: Preprints. 13-15.

Burgess, Helen. 1991. "The Use of Chelating Agents in Conservation Treatments." The Paper Conservator 15: 36-44.

An early article introducing chelators (EDTA and DTPA) to conservation. Explains the structure of chelators and how they complex ions. Includes mention of EDTA not being very effective at removing iron/rust from paper alone, that it works much better if a reducing agent (sodium dithionite) is used first.

Choi, Soyeon. 2007. "Foxing on Paper: A Literature Review." Journal of the American Institute for Conservation 46(2): 137-152. Accessed August 6, 2021.

Cude, Alison. 2010. "TPEN: A Treatment for Iron Gall Ink." Master's Thesis. Queen's University.

Cushman, Matt. 2006. "A New Method for the Treatment of Iron-Stained Architectural Marble: In Situ Reduction of Iron III Using Photovoltaic Polymers and the Introduction of a New Chelating Agent for Conservation." ANAGPIC Conference Papers. 

Dirda, Marian Peck, and Leslie Hill Paisley. 2001. "Stain Reduction Discussion." The Book and Paper Group Annual 20: 51-53.

Dithionite and foxing presented.

Dwan, Antoinette. and Chris Stavroudis. 2020. "Chelating Agents in Paper Conservation." WAAC Newsletter 42(2): 16-22.

Discusses how calcium ions may 'cement' soil onto cellulose fibers and acknowledges how chelating agents will remove calcium and magnesium from paper. Includes an overview of chelator chemistry, focusing on the sequestration of metallic ions. Also discusses the differences in strength between citrates, EDTA, and DTPA. Ends with numerous chelator recipes used by Dwan.

"Foxing." 2021. Paper Conservation Catalog Wiki. Accessed August 5, 2021. https://www.conservation-wiki.com/wiki/BPG_Foxing

Gent, Megan and Jacqueline Rees. 1994. "A Conservation Treatment to Remove Residual Iron from Platinum Prints." The Paper Conservator 18(1): 90-95.

Hart, J. Roger. 1981. "Chelating Agents in the Pulp and Paper Industry." Tappi 64(3): 43-44.

Hendry, Heather. 2001. "Yves Gaucher's Homage to Webern No. 1: A Multidimensional Treatment." The Book and Paper Group Annual 20: 5-7.   

Hernandez, Catalina and Susan Heald. 2009. "The Cleaning of an 18th Century Finger Woven Sash: A practical Twist on Common Wet Cleaning Methods." American Institute for Conservation Textile Specialty Group Postprints 19: 145-155.

Hoshi, E. 2010. "Effects of Chelating Agents to Control Degradation of Japanese Paper Due to Cu Ion." AATA Abstract. Bunkazai Hozon Shufuku Gakkai shi: Kobunkazai no Nagaku 55: 67-75.

Hughes, Amy and Michelle Sullivan. 2016. "Targeted Cleaning of Works on Paper: Rigid Polysaccharide Gels and Conductivity in Aqueous Solutions." The Book and Paper Group Annual 35: 30-41.

Keynan, Daria and Amy Hughes. 2013. "Testing the Waters: New Technical Applications for the Cleaning of Acrylic Paint Films and Paper Supports." The Book and Paper Group Annual 32: 43-51.

Kolar, Jana, Martin Šala, Matija Strlič and Vid Simon Šelih. 2005. "Stabilisation of Paper Containing Iron Gall Ink with Current Aqueous Process." Restaurator 26(3): 181-189.

Lockwood, Kenneth. 1984. "The Effectiveness of Selected Chelate-Reducing Agent Systems in the Removal of Iron Stains from Paper." Proceedings of the Art Conservation Training Programs Conference, Center for Conservation and Technical Studies. Harvard Art Museums: Cambridge, MA. 87-100.

Maitland, Crystal. 2009. "Where Archival and Fine Art Conservation Meet: Applying Iron Gall Ink Antioxidant and Deacidification Treatments to Corrosive Watercolors." The Book and Paper Group Annual 28: 37-45.

Malešič, Jasna, Meta Kojc and V.S. Šelih. 2008. "Assessment of the Effect of Various Bleaching Effects on Papers with Foxing Stains." Restaurator 29(3): 142-154.

If high iron content present: EDTA and dithionite most effective; if no transition metal foxing: sodium borohydride more effective than hydrogen peroxide or calcium hypochlorite.

Maurer, R. 1982. "Chelating Agents in the Textile Industry - A Practical Guide." Canadian Textile Journal 99: 40-44.

Niehaus, Lena, Ute Henniges, Monika Horsky, Thomas Prohaska, Antje Potthast, and Irene Brückle. 2012. "Reducing the Risks of Hydrogen Peroxide Bleaching in Presence of Iron Ions in Paper." Restaurator 33(3): 355-394.

Norville-Day, Heather, Joyce Townsend, and Fiona Johnston. 1998. "A Study of the Effects of Bleaching Treatments on Nineteenth-Century Watercolour Pigments, with Special Reference to Turner's Palette." IPC Conference Papers, London: Proceedings of the fourth international conference of the Institute of Paper Conservation. Leigh, Worcester: Institute of Paper Conservation. 137-149.

Don't bleach watercolors; local suction treatment most damaging; tested EDTA with and without dithionite, TMAB, TEAB.

Novak, Adam and Daria Keynan. 2017. "Recapturing the Subleties." The Book and Paper Group Annual 36: 52-57.

Ammonium hydroxide, ammonium citrate, sodium borohydride

Owen, A. 1994. "Conservation and Curatorial Changes to David Smith's Drawing 'Untitled'." Modern Works, Modern Problems? Conference Papers, Ed. Alison Richmond. London: Institute of Paper Conservation. 100-105. 

Pasnak, Ekaterina. 2017. "Washing Works of Art on Paper Using Rigid Hydrogels Containing Chelating Agents." In Gels in the Conservation of Art, edited by Lora Angelova, Bronwyn Ormsby, Joyce H. Townsend, and Richard Wolbers. London: Archetype. 135-137.

Pemberton, Briony and Libby Melzer. 2010. "A Preliminary Investigation into Three Aids to Washing Paper: XRF Elemental Analysis of Paper Treated with EDTA, TAC and ammonia." In Contributions to the 6th AICCM Book, Paper and Photographic Materials Symposium, Melbourne. Canberra: Australian Institute for the Conservation of Cultural Material. 58-63.

EDTA, Triammonium Citrate

Phenix, Alan and Aviva Burnstock. 1992. "The Removal of Surface Dirt on Paintings with Chelating Agents." The Conservator 16(1): 28-38.

Has a good overview of the chemistry and structure of chelators, and how this relates to their function. Describes the role of chelators in the laundry detergent industry, and how those chemical principles can be applied to (paintings) conservation. Notably, explores the role of chelators (EDTA, citrates) as both sequestering agents and deflocculants/dispersants.

Prestowitz, Brook. 2017. "An Initial Assessment of Local Stain Reduction Using Chelate-Containing Gellan Gum Gels in Paper Conservation." In Gels in the Conservation of Art, edited by Lora Angelova, Bronwyn Ormsby, Joyce H. Townsend, and Richard Wolbers. London: Archetype. 142-144.

Slavin, John. 1990. "The Removal of Salt Deposits from Decorative Paintings on Paper." In: Dirt and Pictures Separated: Papers given at a conference held jointly by UKIC and Tate Gallery. Hackney et al, eds. London: United Kingdom Institute for Conservation. 49-50.

Timár-Balázsy, Ágnes and Dinah Eastop, eds. 2002. "Sequestering Agents." In: Chemical Principles of Textile Conservation. Oxford: Butterworth Heinemann. 221-225.

Tse, S., S. Guild, M. Trojan-Bedynski, and V. Orlandini. 2006. "Effect of aqueous treatments on 19th century iron gall ink documents part 2: Artificial aging by heat, humidity and light." In Pre-conference proceedings of the second iron gall ink meeting, University of Northumbria, Newcastle upon Tyne, 24–27 January 2006, 40–42. Newcastle upon Tyne: University of Northumbria.

Calcium Phytate

See the Phytate Treatment section from the Iron Gall Ink page for additional references.

Bazemore, Avery. 2017. "Chelating Soluble Iron(II) from Iron Gall Ink Using Calcium Phytate in Agar Gel." In Gels in the Conservation of Art, edited by Lora Angelova, Bronwyn Ormsby, Joyce H. Townsend, and Richard Wolbers. London: Archetype. 116-118.

Botti, Lorena, Orietta Mantovani, and Daniele Ruggiero. 2005. "Calcium Phytate in the Treatment of Corrosion Caused by Iron Gall Inks: Effects on Paper." Restaurator 26(1): 44-62.

Henniges, Ute. and Antje Potthast. 2008. "Phytate Treatment of Metallo-gallic inks: Investigation of its Effectiveness on Model and Historic Paper Samples." Restaurator 29(4): 219-234.

Orlandini, Valeria. 2009. "Effect of Aqueous Treatments on Nineteenth-Century Iron-Gall-Ink Documents: Calcium Phytate Treatment--Optimization of Existing Protocols."The Book and Paper Group Annual 28.

Zappala, Antonio and Caroline De Stefani. "Evaluation of the Effectiveness of Stabilization Methods: Treatments by Deacidification, Trehalose, Phytates on Iron Gall Inks." Restaurator 26(1): 36-43.

Citrates

Brockman, Madison. 2020. "Accelerated Aging Study of Papers Treated with Citrate Solutions." WAAC Newsletter 42(1): 11-13.

Caryle, Leslie, Joyce Townsend and Stephen Hackney. 1990. "Triammonium Citrate: An Investigation into its Application for Surface Cleaning." In: Dirt and Pictures Separated: Papers given at a conference held jointly by UKIC and the Tate Gallery. Hackney et al, eds. London: United Kingdom Institute for Conservation of Historic and Artistic Works. Accessed August 9, 2021.

An early article testing numerous cleaning agents, including several chelators (EDTA, ammonium citrates, sodium citrates), to gauge their efficacy at cleaning the surface of an oil painting. Determined that for their purposes, pH was an important factor in the cleaning action. Describes how different chelators may work more quickly than others, but still clean the surface to the same extent.

Dwan, Antoinette. 2015. "Ammonium Citrates for Stain Removal in Paper." WAAC Newsletter 37(3): 10-12.

Hashimoto, Laura R. 2015. "Examining Effects of Ammonium Citrate Immersions on Paper." Poster presented at ANAGPIC.

Morrison, Rachel, Abigail Bagley-Young, Aviva Burnstock, Klaus Jan van den Berg and Hanl van Keulen. 2007. "An Investigation of Parameters for the Use of Citrate Solutions for Surface Cleaning Unvarnished Paintings." Studies in Conservation 52(4): 255-270.

Stavroudis, Chris. 2015. "A Tale of Two Citrates (Actually Four)." WAAC Newsletter 37(2): 15.

Venus, P., Henniges, U., Brückle, I., Maitland, C., Smith, T. J., Moriarty, M., Potthast, A. 2025. "Testing Ammonium Citrates for Enhanced Washing of Paper". Journal of the American Institute for Conservation, 1–20. https://doi.org/10.1080/01971360.2025.2464337

Venus et al. discuss the use of ammonium citrates as an additive for "enhanced" paper washing, a more powerful brightening agent than washing alone, but less aggressive than a bleach. The authors stress the importance of using a calcium bicarbonate solution, rather than calcium hydroxide, as a rinsing step to reintroduce an alkaline reserve.

EDTA and DTPA

Abbey Newsletter. 1985. "DTPA, a Chelate that Helps Two Ways." The Abbey Newsletter 9(5): 80. Accessed August 9, 2021.

Brockman, Madison and E. Farek. 2019. "Investigation into the Reduction of Foxing Stains in Paper." The Book and Paper Group Annual 38: 102-111.

Lehtaru, Jaan and Tullio Ilomets. 1997. "Use of Chelating Agent EDTA with Sodium Thiosulphate and Sodium Borohydride in Bleaching Treatment." Restaurator 18(4): 191-200.

Mina, Laura. 2020. "Foxy Underpants: Or the Use of Chelators and Enzymes to Reduce Foxing Stains on Early Nineteenth Century Men's Linen Underpants." Journal of the American Institute for Conservation 59(1): 3-17. Accessed August 5, 2021.

Prestowitz, Brook, Charis Theodorakopoulos, and Jane F. Colbourne. 2016. "Tip: A Preliminary Investigation into the use of [DTPA] Diethylenetriaminepentaacetic Acid and [EDTA] Ethylenediaminetetraacetic Acid to Treat Iron-Induced Foxing in Paper Objects." The Book and Paper Group Annual 35: 163-170.

Suryawanshi, D.G. and S.K. Bisaria. 2005. "Removing Metallic Stains from Paper Objects Using Chelating Agent EDTA." Restaurator 26(4): 276-285.

History of This Page

This page was created in August 2021 by Jennifer Evers using a bibliography submitted by Theresa J. Smith.