Glass - Back to the Future!



Presenting Author:
Alexandra Rodrigues
<aj.rodrigues@campus.fct.unl.pt>

article posted 08 Feb 2016


Alexandra Rodrigues has both Bachelor and Masters degrees in Conservation and Restoration, with specialization in Glass, Stained-Glass, and Glass Biodeterioration. Her research has been focused on the study and characterization of glass, stained-glass, and on the deterioration mechanisms.

She is currently undertaking PhD studies in Conservation Science with the subject "Glass Collection from Museu Nacional de Arte Antiga: study and preservation".

The project concerns:


as well as reproduction of glass for artificial corrosion experiments using several analytical techniques, including Secondary Ion Mass Spectrometry (SIMS).






The Glass Collection of King Ferdinand II Portugal: A ToF-SIMS study of glass corrosion

Alexandra Rodrigues a*, Sarah Fearn b, Márcia Vilarigues a

It is well known that glass corrosion particularly affects glass objects in the museum environment [1-4]. A study of glass within the Museu Nacional de Arte Antiga (MNAA) in Lisbon, Portugal, showed that some of the objects in the historical glass collection of King-Consort Ferdinand II (1837-1853), that came from the National Palace of Necessidades in Lisbon, were weeping and crizzling (see Figures 1 and 2).

Some rare cases even evidenced crystalline corrosion products forming at the surface (Figure 3). The future preservation of these glass objects depends on a deeper knowledge of the chemical-physical phenomena that are occurring in the glass surfaces. The type and features of these phenomena, the change in surface composition, chemical stability, different ways of leaching and the alteration products are all very important factors coupled with the need to fully understand the role of the glass composition and corrosion agents.

   

Figure 1: MNAA947vid                         Figure 2: MNAA1074vid
              weeping.                                    visible cracking & crizzling.



Figure 3: MNAA1130vid with corrosion products.


Due to the historical importance and cultural significance of these glass objects, non-destructive analysis (micro energy dispersive X-ray fluorescence, µ-EDXRF, and proton induced X-ray/gamma emission, PIXE/PIGE) are being performed on the glass objects, and information on chemical composition and the glass types present in this collection is being obtained. This compositional data, together with literature information on chemical composition of historical glass of the same types and typologies, was used as a guideline for the production of replica glass samples. Replicas of soda, soda-lime, calco-potassic, lead, and high-lime-low-alkali glass have been produced. The use of replica materials has enabled the study of the corrosion mechanisms of these glass types, with the aim of finding a suitable environment for the safe storage of all the glass objects in the museum,using the more destructive analytical technique of secondary ion mass spectrometry.

The application of time of flight secondary ion mass spectrometry (ToF-SIMS) in conservation science and archaeometry has recently become more widespread [5] and in this study, ToF-SIMS depth profiling was used to monitor the compositional changes that occur during the ambient corrosion process. In this work the replica glass was aged at room temperature under known atmospheric humidities (45%, 55%, 65% and 75-80%) for increasing periods of time (up to 1 year). The compositional changes occurring in the replica glasses will be presented, along with a discussion of possible storage for these vulnerable glass objects.

References:

1. Fearn S, McPhail DS, Oakley V. Room temperature corrosion of museum glass: an investigation using low-energy SIMS. Appl Surf Sci [Internet]. 2004 Jun [cited 2012 Nov 27];231-232:510-4.

2. Fearn S, Mcphail DS. Moisture attack on museum glass measured by SIMS. Phys Chem Glas. 2005;46(5):505-11.

3. Robinet L, Fearn S, Eremin K, Pulham C, Hall C. Understanding glass deterioration in museum collections: a multi-disciplinary approach. In: ICOM Committee for Conservation 2005, Vol 1, Glass and Ceramics. 2005. p. 139-45.

4. Fearn S, McPhail DS, Hagenhoff B, Tallarek E. TOF-SIMS analysis of corroding museum glass. Appl Surf Sci [Internet]. 2006 Jul [cited 2013 Jan 9];252(19):7136-9.

5. McPhail DS. Some applications of SIMS in conservation science, archaeometry and cosmochemistry. Appl Surf Sci [Internet]. 2006 Jul [cited 2014 Mar 25];252(19):7107-12.

Institutions:

a) Departamento de Conservação e Restauro, Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Portugal and Research unit, VICARTE - Glass and Ceramics for the Arts

b) Materials Department, Imperial College London