Can material analysis help the preservation and conservation of my Written Aretfact?
Degradation and Conservation
Claudia Colini
WAs are items of value for the collectivity, as they are part of the cultural heritage of people and for this reason their integrity needs to be preserved. According to the definition adopted by the Committee for Conservation of ICOM (ICOM-CC 2008), the term Conservation encompasses ‘all measures and actions aimed at safeguarding tangible cultural heritage while ensuring its accessibility to present and future generations’ and includes Preventive Conservation, Remedial Conservation and Restoration. Preventive Conservation, elsewhere called Preservation, includes ‘all measures and actions aimed at avoiding and minimising future deterioration or loss’, while Remedial Conservation, also called Interventive Conservation embraces ‘all actions directly applied to an item or a group of items aimed at arresting current damaging processes or reinforcing their structure’. The definition of Restoration - ‘all actions directly applied to a single and stable item aimed at facilitating its appreciation, understanding and use’ - is more controversial, as for the UK/US-trained book conservators the term assumed the negative connotation of treatments that do not respect the object. The Code of Ethics of the Canadian Association for the Conservation of Cultural Property reflects on this aspect, defining Restoration as ‘All actions taken to modify the existing materials and structure of a cultural property to represent a known earlier state. The aim of restoration is to reveal the culturally significant qualities of a cultural property. Restoration is based on respect for the remaining original material and clear evidence of the earlier state’ (CAC and CAP 2000).
The need for synergy between material analysis and preservation-conservation is evident, as the former can offer essential information to conduct a successful treatment. Moreover, studies in conservation performed with the help of the natural sciences have unveiled the degradation patterns of several materials and will keep doing so in the future (see 'How does my WA change through time?').
In fact, knowing the materials that constitute WAs, their chemical and physical characteristics as well as their degradation patterns, is pivotal for the planning of a conservation treatment and an adequate preservation environment. For example, the application of the reduction treatment with tert-butylamine borane (TBAB) for oxidised paper won’t be advisable if modern inks used for stamps are present, since they will rapidly disappear (Bicchieri/Brusa 1997). Additionally, scientific studies can also be used to test and identify new suitable materials and procedures for conservation, as, for example, the application of microgels for paper cleaning (Di Napoli et al. 2020).
Another possible application consists in the identification of degradation products, observable exclusively in connection to specific materials, conditions, or biodeteriogens. An example for this case is the study on the formation of crystalline deposits on a number of papyri kept between glasses (Neate et al. 2011).
Material analysis can also unveil unsuitable restoration or protection techniques applied to inorganic-based writing supports, as well as appropriate conservation and preservation methods. For instance, the application of synthetic polymers to degraded wall paintings resulted in accelerated deterioration phenomena and severe detachments of the surface paint layer, after a few years of their application (Baglioni and Giorgi, 2006). Meanwhile, the treatment of the same wall paintings, mostly made of lime, with solutions consisting of ammonium carbonate ((NH4)2SO4), barium hydroxide (Ba(OH)2) and nanosized calcium hydroxide (Ca(OH)2) will prevent further weathering, reverse the degradation that has already occurred and will enhance the adhesive properties to the newly applied layer of paint (Baglioni and Giorgi, 2006). Another example is the application of organic compounds, such as milk, egg, and resins, to limestone-based historical monuments, which primarily protected the surface and prepared it for the pigment application, but at a later stage led to the formation of calcium oxalates on the surface of these monuments (Conti et al., 2012).
External organisms, like insects, rodents, moulds and bacteria, can alter and degrade WAs. Knowing their species and the environmental conditions optimal for their proliferation is useful when planning for safe storage and appropriate conservation treatment. For example, the identification of the species of degrading fungi through genomic and proteomic analysis was used to optimise preservation strategies and implement targeted conservation treatments (Sterflinger/Pinzari 2012; Migliore et al. 2019).