Cancy Chu

Cancy Chu (PhD in Cultural Materials Conservation, 2023) ‘Preserving Plastics in Paper-Based Collections’

Plastics, referring to semi- or fully synthetic mouldable polymeric materials, are now found in a wide range of cultural heritage materials. Ongoing research focused on plastics in museum collections show that the chemical stability of certain plastics are short-lived. These unstable plastics may additionally produce acidic products during deterioration, causing damage to neighbouring collections. Existing case studies of the rapid degradation of plastic materials associated with book and paper collections suggest the need for conservation attention to manage deterioration in libraries and archives. However, the types and condition of plastics in paper-based collections are not documented. Additionally, there are currently no targeted preservation strategies available.

This dissertation aims to gain an understanding of plastics in paper-based collections in order to make informed preservation recommendations. Interdisciplinary methods were employed in a four-stage progressive investigation:

1. Firstly, a literature review of relevant preservation practices situates the research within the plastics conservation field. A classification of plastics in paper-based collections is proposed. Existing preservation methods addressing each material subtype are summarised, revealing a gap in the literature on plastics associated with paper materials: bindings, organisers and protectors.

2. Next, an industry survey of professionals working in Australian archives was used to assess the need for preservation strategies. Results show that plastics are pervasive in Australian archives, found in at least 90% of responding institutions. Furthermore, plastics associated with paper in archives are reported in poor condition by more than half of respondents. Respondents rated highly the need for storage strategies and standardised guidelines, supporting a need for preservation solutions.

3. To understand plastics in paper-based collections, the object types, condition, and preservation strategies were determined though collection surveys of post-1950s paper-based collections at the South Australian Museum Archive in Adelaide, the Art Gallery of New South Wales in Sydney, and the Grimwade Centre for Cultural Materials Conservation in Melbourne. Using ATR-FTIR, 11 common polymers were identified, and ten binding structures were described. Observed deterioration was classified under four contributing causes. Based on observations, preservation recommendations were proposed addressing each of the four deterioration categories.

4. Lastly, a proposed storage strategy for plasticised poly(vinyl chloride) book covers was tested using artificial ageing. Three common sheet materials used in paper conservation were compared as possible interleaving materials. Although interleaving was observed to benefit the reduction of ink offset, other types of damage were accelerated by all three materials. This stage demonstrates the specific testing needs of a composite material combination.

Findings contribute to a deeper understanding of effective preservation approaches for plastics in paper-based collections. Overall, results show the need for storage guidelines, specific testing of composite materials, and interdisciplinary collaboration to improve preservation approaches.

This thesis is centred on practical industry outcomes and is amongst the first to specifically consider the overlap between plastics conservation and paper-based collections. Knowledge gaps addressed include material types, deterioration patterns, and suitable preservation methods. Although the thesis is focused on Australian collections, resulting recommendations are broadly relevant to paper-based collections, benefiting the preservation of information and culture for present and future generations.

Supervisors: Associate Professor Petronella Nel, Professor Robyn Sloggett