Conservation of a mid-19th Century Pretiosa Mitre From New Norcia, Western Australia

Abstract

Conservation treatment and associated scientific analysis of a significant pretiosa (Latin, precious) mitre from the Benedictine Monastery at New Norcia, Western Australia is presented. Analysis of the pH and surface chloride readings showed that increased acidity contributed to the deterioration of the silk fibres, which could be directly related to the levels of retained sweat indicated by the measured chloride ion activity. Migration of acidity from the external silk fabric into the oiled cardboard internal stiffeners necessitated the insertion of replica pieces into the subsequently disassembled mitre. Prior to this work, the corroded gilded silver alloy decorative elements on the disassembled mitre were conserved in situ through reductive consolidation in a 0.1 wt.% sodium dithionite solution at neutral pH. Considerable couching was conducted to stabilise the metalwork and the damaged silk panels on both faces of the mitre, owing to extensive wear from repeated and extended use. Extensive biological degradation of the original silk lining had rendered the original materials with insufficient structural strength to undergo conservation treatment, ultimately requiring replacement with a matching modern silk. All original materials were kept as part of the research collection held by the New Norcia community to allow for future possible DNA analyses.

Keywords:

• Mitre
• Sweat
• Acidity
• Corrosion
• Silk
• Conservation
• Dithionite
• Reduction

ORCID

Ian D Macleod http://orcid.org/0000-0002-2947-3587

And Rinske Car http://orcid.org/0000-0001-9073-0143

Additional information

Funding

This work was supported by Copland Foundation [grant no 0012].

Notes on contributors

Ian D MacLeod

Author Biographies

Ian MacLeod was an Executive Director of the Western Australian Museum and a hands on conservator since 1978. His main research area is the decay of materials found on historic shipwrecks. He managed the relocation of more than 8.5 million objects to a centralised collection management and research facility which is fully climate controlled. He enjoys the application of significance and treatment priorities to the management of collections in museums and for submerged cultural heritage. Ian has a passion for decay and for the integration of the spiritual with the material health of collections.

And Rinske Car

Rinske Car is a textile conservator who has more than 40 years of experience in the stabilisation and treatment of ancient textiles from archaeological sites. She used enzymes to remove frass from termite-damaged fabrics. For more than ten years she was a lecturer in textiles at Edith Cowan University in Perth where she developed the use of native plants as sources of fast colour dyes for silks and wool. She designed and supervised the manufacture of hand-knotted carpets. Rinske is the proprietor of the Denmark River Textile Conservation Studio in Denmark, Western Australia which specialises in treatment of complex historic textiles.