This week’s #ConservationBookClub blog post focuses on the subject of remoistenable tissue repair.
In conservation, the purpose of repair is to stabilise the object to prevent further deterioration. We provide structural support for damage to the substrate (e.g. paper, parchment, papyrus) ranging from small tears or losses all the way up to severe damage, fragmentation and complete loss of strength. Many collection objects here at the Chester Beatty have a degree of moisture sensitivity, including fugitive pigments, iron gall ink and copper corrosion, as well as coated papers and parchment. In these cases, remoistenable tissue is often chosen as a repair method to control and reduce the application of moisture and allow for accurate and quick repairs.
A remoistenable tissue, also known as a ‘coated tissue paper’ or ‘adhesive pre-coated repair material’ usually consists of a layer of thin Japanese tissue coated with an adhesive film. Prepared in advance and allowed to dry, the adhesive layer can then be reactivated. We tend to reactivate our remoistenable tissue with water or a dilute solution of adhesive, although solvents and heat can also be used (these are known respectively as solvent-set and heat-set tissues).
When making a batch of remoistenable tissue, the paper can be toned prior to coating with adhesive to give a better match on the finished repair. Once dry, we store the finished sheets on the Melinex backing they are cast on. This keeps them safe and flat until they are needed. The final coated tissue can be shaped to fit the area needing repair before it is removed from the Melinex. It is tricky to achieve a feathered edge, but this is not usually a problem when working with very thin Japanese papers.
There are many factors to consider when choosing the paper and adhesive, including transparency, strength, aging properties, ease of application, and reactivation technique. Practical and aesthetic considerations have to be balanced-the repair needs to be both functional and sympathetic to the object.
At the Chester Beatty we frequently use remoistenable tissue prepared with Methocel A4M for repair of paper with moisture sensitive media, and isinglass remoistenable tissue for parchment repair. I have completed small scale repairs using remoistenable tissue prepared with both of the adhesives and have learnt how to apply them successfully. The type of Japanese tissue we use varies depending on the material being repaired but often the most lightweight paper is optimal, such as Tengujo or RK-00.
Once I return to the lab, I hope to make a range of remoistenable tissues testing different papers and adhesives for use in repairing and potentially lining multiple folios in a Syriac manuscript that is severely damaged by iron gall ink corrosion. I hope I can share some of the practical considerations involved in making remoistenable tissues during this process.
There are many great articles and resources on the preparation and treatment of objects using remoistenable tissues and I wanted to highlight a few that I found particularly interesting:
1. Irene Brückle, “Update: Remoistenable Lining with Methylcellulose Adhesive Preparation.”
This was one of the earliest articles on the subject of remoistenable tissue and was formative for many conservators, leading to increased use and research into the topic. It focuses on the use of a methylcellulose remoistenable tissue as an alternative lining technique for moisture sensitive objects. However, it also sets the scene for further investigation into the potential uses of remoistenable tissue for repair, as shown by Sarah S. Wagner’s 1996 article, “Remoistenable Tissue Part II–Variations on a Theme.”
2. Andrea Pataki, “Remoistenable tissue preparation and its practical aspects.”
A thorough and useful resource to refer to on the subject of remoistenable tissues, this article discusses the swelling properties of different adhesives in regard to their suitability for use in remoistenable tissue applications. A range of adhesives and their activation methods are analysed in detail. Adhesives tested include gelatine, isinglass, Funori/JunFunori, cellulose ethers, and synthetic adhesives such as Paraloid B72. She examines the concentration required, their activation solvents and the adhesion power and flexibility of the final repair. Berlin tissue was the main support material used during testing.
Restaurator, Vol 30, 2009, pp. 51-69.
For a detailed analysis of the surface characteristics and opacity of lightweight Japanese tissues, I would also recommend the co-authored 2014 article by Andrea Pataki-Hundt and Cosima Walter, “Comparison of lightweight Japanese tissues for overall stabilization of documents damaged by iron gall ink corrosion and an alternative to silkscreen frames.”
3. Priscilla Anderson and Sara Reidell, “Adhesive pre-coated repair materials.”
This helpful 2009 handout contains a table discussing the advantages and disadvantages of remoistenable tissue repair. It also covers the preparation and reactivation methods for remoistenable tissues made with a range of adhesives. Sarah Reidell also has a comprehensive bibliography about pre-coated repair materials on her website here.
4. Ban Van Velzen and Eliza Jacobi “Instructables: Remoistenable Tissue (1)”
“Instructables: Repair on Iron Gall Ink with Remoistenable Tissue (2)”
These two handouts offer clear step-by-step instructions on the preparation and application of a 3% gelatine remoistenable tissue. The first handout covers the materials and technique of creating the adhesive coated tissue and the second covers how to cut the tissue and apply the repair. Although these handouts focus on gelatine remoistenable tissue much of the process can be applied to remoistenable tissue made with other adhesives.
5. Sonja Titus et al., “Stabilising local areas of loss in iron gall ink copy documents from the Savigny estate.”
This article is a great example of how remoistenable tissue can be used for the stabilisation of areas of paper corroded by iron gall ink. Using Berlin Tissue (kozo-mitsumata fibre content) and precoating it with gelatine (which can have a stabilising influence on iron gall ink), the author was able to reactivate and adhere the prepared tissue with the aid of a suction table. She discusses how remoistenable tissue can be applied with great precision, and minimal moisture.
6. Valéria Duplat et al., “Steel versus Paper: The Conservation of a Piece of Modern Art Consisting of a Rust Print on Paper.”
The rapid and severe damage to a contemporary print caused by the iron in the paper, necessitated immediate intervention. The print was treated with a calcium phytate solution and deacidified. 4% remoistenable tissue impregnated with gelatine was used in two ways: firstly, using strips to secure fractures and fragments, and secondly for lining the artwork by reactivating the remoistenable tissue with a dilute solution of gelatine.
7. Kristine Rose, “The Conservation of a seventeenth-century Persian Shahnama.”
Kristine Rose-Beers, ‘Parchment, pigments and perforations: developing a treatment methodology for an 8th century Qur’an Manuscript at the Chester Beatty.”
These two articles by Kristine Rose-Beers, the Head of Conservation at the Chester Beatty and our colleague, discuss the treatment of two important manuscripts. The first article records the conservation of Cambridge University Library’s earliest and most finely decorated copy of the Shahnama (CUL Add 269), while the 2019 article covers the initial stages of treatment for an early eighth-century Qur’an manuscript at the Chester Beatty (CBL Is 1404).
In both treatments remoistenable tissue was utilised for repair. The Cambridge University Shahnama had suffered deterioration of the ruled border lines caused by copper corrosion. Methocel A4M was used in solution with wheat starch paste to make a remoistenable tissue. This adhesive was chosen as it is resistant to acid catalysed hydrolysis, the process by which verdigris degrades, and the remoistenable tissue limits moisture which could further increase corrosion of copper pigments or affect the highly fugitive pigments. The Chester Beatty Qu’ran was in poor condition due to previous treatments using unsuitable materials and severe iron gall ink corrosion. As part of its conservation Kristine supported losses to the text areas using toned remoistenable tissue prepared with Isinglass.
Edinburgh Conference Papers 2006, Institute of Conservation: 2007, pp. 79-86.
Anali Gazi Husrev-Begove Biblioteke, 26 (40), 2019, pp. 331-352.
8. Cathleen A. Baker, “Sodium Carboxymethylcellulose (SCMC) Re-evaluated for Paper, Book, Papyrus, and Parchment Conservation.”
Leyla Lau-Lamb, “A New Material for the Conservation of Papyrus.”
Both of these articles highlight the value of making a remoistenable tissue using the adhesive sodium carboxymethylcellulose (SCMC). They discuss the adhesive properties and stability of SCMC and give examples of how it can be used for repair including remoistenable backings, or in small remoistenable strips (bridges) for papyrus conservation.
9. Helen Shenton, “Overview of the conservation of Codex Sinaiticus at the British Library.”
Remoistenable tissue was used as part of a collaborative project to repair the Codex Sinaiticus, the earliest manuscript of the complete New Testament and several books of the Old Testament in parchment. The existing 400 leaves are divided between four locations,St Catherine’s Monastery in Sinai, the British Library, Leipzig University Library, and the National Library in St Petersburg. Isinglass was chosen as an adhesive due to its tackiness, ease of removal and ability to adhere at room temperature. It was used to re-adhere lifting repairs and also as a remoistenable tissue prepared with 5% Salianski Isinglass on 11gsm Tengujo Japanese tissue. For more information about this preeminent manuscript and its conservation please visit the website: codexsinaiticus.org
10. Eliza Jacobi, Birgit Reissland, Claire Phan Tan Luu, Bas van Velzen and Frank Ligterink “Rendering the Invisible Visible - Preventing Solvent-Induced Migration During Local Repairs on Iron Gall Ink.”
Eliza Jacobi, “Moisture and mending: A method for doing local repairs on iron-gall ink.”
As mentioned in my previous blog post about iron gall ink, these two articles by Eliza Jacobi et al. helped set the standard for repair of iron gall ink corroded paper using remoistenable tissue. Jacobi tested a range of adhesives and application methods and found that only remoistenable tissue provided an adhesive layer of equal thickness and limited the water content such that reproducibly good results were achieved. These articles also develop a controlled methodology for preparing and applying the remoistenable tissue that many conservators use today.
11. Katherine Lechuga, “Aquazol Coated remoistenable mending tissues.”
This study evaluates the synthetic adhesive Aquazol for use as an adhesive when making a remoistenable tissue. Remoistenable tissues were prepared by coating them with Aquazol 50 and 200 in different concentration solutions and using water and alcohol as solvents. These remoistenable tissues were then tested for tear repair on a range of papers and their characteristics assessed. The article concludes Aquazol remoistenable tissues are suitable for treating water sensitive media, coated papers and papers prone to tide line formation. We haven’t worked with Aquazol at the Chester Beatty, but thought this article was fascinating.
12. Christa Hofmann et al., “Studies on the Conservation of Verdigris on Paper.”
This paper focuses on the chemical degradation of verdigris and potential treatment options. Remoistenable tissues are offered as one option for mechanical stabilisation. Different aqueous and non-aqueous adhesives are tested, including their application, activation with water, ethanol or heat, and the aging properties of the coated tissues.
13. Lauren M. Varga, Jennifer K. Herrmann, and Kathleen Ludwig, “Heat-Set Tissue: Finding a Practical Solution of Adhesives.”
Katherine S. Kelly et al., “Heat- and Solvent-Set Repair Tissues.”
Two reports on heat-set and solvent-set repair tissues by The National Archives and Records Administration and the Library of Congress; the 2020 article builds on research completed in 2015. The institutions jointly tested a range of synthetic adhesives: Lascaux 498 HV, Lascaux 303 HV, Avanse MV-100, Plextol B500, Aquazol 200, and Aquazol 500. Japanese papers coated with these adhesives were applied to substrates using both heat and solvent set methods. Analytical testing was carried out and found that the activation method – heat or solvent, did not affect the aging properties of the adhesives. Not all the adhesives passed the testing process for reasons such as poor adhesion, lack of reversibility, blocking or colour changes over time.
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Sophie Coulthard, Conservation Intern 2020/21.