Characterization and Identification of Varnishes on Copper Alloys by Means of UV Imaging and FTIR
Source abstract
Abstract
The application of varnishes on the surface of metal objects has been a very common practice since antiquity, both for protective and aesthetic purposes. One specific case concerns the use of tinted varnishes on copper alloys in order to mimic gilding. This practice, especially flourishing in the 19th century for scientific instruments, decorative objects, and liturgical items, results in large museum collections of varnished copper alloys that need to be preserved. One of the main challenges for conservators and restorers deals with the identification of the varnishes through non-invasive and affordable analytical techniques. We hereby present the experimental methodology developed in the framework of the LacCA and VERILOR projects at the Haute École ARC of Neuchâtel for the identification of gold varnishes on brass. After extensive documentary research and analytical campaigns on varnished museum objects, various historic shellac-based varnishes were created and applied by different methods on a range of brass substrates with different finishes. The samples were then characterized by UV imaging and infrared spectroscopy before and after artificial ageing. The comparative study of these two techniques was performed for different thicknesses of the same varnish and for different shellac grades in order to implement an identification methodology based on simple non-invasive examination and analytical tools, which are accessible to conservators.
Source: crossref · Quality: baseline
Research context
OpenAlex topics: Cultural Heritage Materials Analysis · Conservation Techniques and Studies · Building materials and conservation
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Haute Ecole Arc Conservation Restauration, HES-SO University of Applied Sciences and Arts Western Switzerland, 2000 Neuchâtel, Switzerland
Funding
Haute Ecole Spécialisée de Suisse Occidentale
References (29)
Show source-provided references
1. Halleux, R. (2019). Les Alchimistes grecs. Tome I: Papyrus de Leyde—Papyrus de Stockholm—Recettes, Les belles lettres. [3rd ed.].
2. Verlet, P. (1987). Les bronzes dorés francais du XVIIIe siècle, Editions A & J Picard.
3. L’illusion de l’or10.4000/archeosciences.2527 ↗
4. Perego, F. (2005). Dictionnaire des matériaux du peintre, Éditions Belin.
5. Schröter, J., Michel, A., Mirabaud, S., Brambilla, L., Paris, C., and Bellot-Gurlet, L. (2019, January 2–6). Transparent varnishes on copper alloys dating from the 19th century: Characterization and identification strategies. Proceedings of the interim meeting of the ICOM-CC metals working group, Neuchâtel, Switzerland.
6. Pinna, D., Galeotti, M., and Mazzeo, R. (2009). Ultraviolet fluorescence imaging. Scientific Examination for the Investigation of Paintings: A Handbook for Conservator-Restorers, Centro Di.
7. Thackray, A. (2014). A methodology for the conservation of furniture mounts. V A Conserv. J., 62.
8. Practical notes on ultraviolet technical photography for art examination10.14568/cp2015006 ↗
9. Measday, D. (2017). A summary of ultra-violet fluorescent materials relevant to conservation. AICCM Natl. Newsl., 137. Available online: https://bit.ly/3pjAq8U.
10. Umney, N., and Rivers, S. (2013). Conservation of Furniture, Routledge.
11. (2021, February 10). The Conservation and Art Materials Encyclopedia Online (CAMEO). Available online: http://cameo.mfa.org/wiki/Category:Materials_database.
12. Thomson, C. (1991, January 3–8). Last but not least, examination and interpretation of coatings on brass hardware. Proceedings of the AIC Annual Meeting, Albuquerque, NM, USA.
13. Drayman-Weisser, T. (2000). The treatment of false gilding: A case study. Gilded Metals: History, Technology and Conservation, Archetype Publications Ltd.
14. Jeanneret, R. (2010). Approche Pluridisciplinaire Pour le Traitement de Conservation-Restauration d’un Quart de Cercle Mural du 18ème Siècle du Musée des Confluences de Lyon. [Master’s Thesis, HES-SO].
15. Pinna, D., Galeotti, M., and Mazzeo, R. (2009). Transform infrared spectroscopy. Scientific Examination for the Investigation of Paintings: A Handbook for Conservator-Restorers, Centro Di.
16. Echard, J.-P. (2002). Le vernis des instruments de musique: Principe et spécificités. Art et Chimie: Les Polymers, CNRS Editions.
17. Caratterizzazione non invasiva delle vernici da ottone degli strumenti scientifici: Ricette storiche, realizzazione di provini verniciati, ricerca analitica e applicazioni “in situ” su strumenti storici
18. Salvadori, B., Galeotti, M., Porcinai, S., and Cagnini, A. Non-invasive FT-IR reflection to assess and monitor coatings on metals, In proceedings of the New strategies for diagnostics of conservation treatments conference, Amsterdam, The Netherlands, 7–8 February 2019.
19. Tripier-Deveaux, A.-M. (1845). Traité Théorique et Pratique sur l’art de Faire les Vernis: Suivi de Deux Mémoires, l’un sur les Dangers Qui menacent les Peintures Vernies d’extérieurs, l’autre sur les Précautions à Prendre Pour Assurer aux Revernissages la Même Durée Qu’aux Vernissages Faits sur les Peintures Fraîches, Librairie scientifique-industrielle de L. Mathias.
20. Société de l’École d’horlogerie de Paris, and Chambre syndicale de l’horlogerie de Paris (1876). Revue Chronométrique, Organe des Sociétés D’horlogerie et des Chambres Syndicales.
21. Roseleur, A. (1873). Guide Pratique du Doreur, de L’argenteur et du Galvanoplaste: Manipulations Hydroplastiques, Plazanet.
22. Fluorescence of paint and varnish layers (Part I)
23. Mills, J.S., and White, R. (1987). The Organic Chemistry of Museum Objects, Butterworth & Co.10.1016/B978-0-408-11810-1.50006-4 ↗
24. ISO 16474-3:2013 (2013). Paints and Varnishes—Methods of Exposure to Laboratory Light Sources—Part 3: Fluorescent UV Lamps, ISO.
25. The Use of Ultraviolet Induced Visible-Fluorescence in the Examination of Museum Objects, Part 2
26. (2021, February 10). The Conservation and Art Materials Encyclopedia Online (CAMEO). Available online: http://cameo.mfa.org/wiki/Rosin.
27. Derrick, M.R., Stulik, D.C., and Landry, J.M. (1999). Infrared Spectroscopy in Conservation Science, Getty Conservation Institute.
28. Derry, J. (2012). Investigating Shellac: Documenting the Process, Defining the Product. A Study on the Processing Methods of Shellac, and the Analysis of Selected Physical and Chemical Characteristics. [Master’s Thesis, University of Oslo].
29. Nakata, Y., and Murakami, S. (2010). FTIR Talk Letter, Shimadzu.