Making It Stick: Challenges with the Re-Coating of Miró’s Outdoor Bronze Sculpture Entitled Personnage

Jessica Chasen, Julie Wolfe, Arlen Heginbotham, and Herant Khanjian

Abstract

The J. Paul Getty Museum has carried out a technical study and treatment of Joan Miró’s outdoor bronze sculpture entitled Personnage (designed 1976, cast 1985). Brought into the conservation lab to address issues with surface efflorescence of core material and to restore aged, protective coatings, a multitude of issues were raised surrounding its history of manufacture, complex scientific analyses of the coatings, and challenging treatment options. Examination of the Getty cast, fabricated at Fonderia Bonvicini in Verona in 1985, revealed significant differences from earlier casts and the complicated edition history was clarified through dialogues with the foundry, archival research, and x-radiography. The paper will review quantitative analysis of the bronze alloys with XRF, complemented by trace elemental analysis with ICP-MS. The work contributes reference data for comparison with other Miró bronzes and introduces difficulties found in the detection of elements in modern silicon bronze alloys using a handheld XRF system alone. The early stages of the treatment involved the removal of aged coatings using solid carbon dioxide blasting and solvent cleaning with the aid of FTIR analysis to identify the removal layer-by-layer. A range of maintenance waxes, a previously undocumented partial Incralac coating, and underlying earlier coatings were characterized, along with their solubilities, in the course of the treatment. Fully stripped as much as possible, the olive green and black patina on the surface of the bronze appeared mottled and disturbed since the porosity of the casting allowed salt migration and localized corrosion. An acrylic lacquer, called Permalac, was initially chosen as it now supplies a range of complimentary products that would allow for reintegration, including toned lacquers. Issues with poor adhesion were immediately apparent despite utilizing the manufacture’s recommended guidelines for coating application. The experience led to the development of a more extensive methodology to evaluate the adhesion and quality of a test coating using ASTM standards that were modified for use on outdoor sculpture. The process included testing of several different coating mixtures and application protocols on both copper coupons and the sculpture itself. The approach revealed interesting information regarding the effects of diluents and drying times on the performance of the film. The analysis and the treatment reinforced the need for constant adaptation, with several cycles of scientific analysis and treatment testing yielding incremental improvements in the performance and appearance of the surface coating. It is hoped that this methodology, including the protocols used for testing, can be applied to other outdoor bronze treatments and that technical data amassed can contribute to the growing body of literature on Miró outdoor sculpture and contemporary bronze casting

2019 | Uncasville | Volume 26