CHALLENGES IN THE CONSERVATION OF SYNTHETIC POLYMERS: discolouration of plastic objects at the Museum of Contemporary Art, Universidade de São Paulo

André Maragno, Patricia Schossler, Márcia Rizzutto

Plastics are present in all the spheres of the modern society and consequently it is to expect that, through the time, they will be part of museums and/or private collections. Recent surveys in collections pointed out the quite fast degradation of some polymeric materials if compared to traditional materials. To overcome these problems the research concerning the conservation of plastic objects has been increasing in the last years, especially with focus on the understanding of the aging of the polymeric matrix. Only a few research groups are studying the identification and aging of additives, like colorants and synthetic organic pigments present in modern and contemporary artworks.
Synthetic organic pigments were first commercialized in the 1940 and today are widely used in modern and contemporary works of art, especially to approximate hues normally achieved with mineral pigments now considered toxic. Identification of these pigments can help to inform conservation treatment and display decisions as well as to provide information about dates of execution of works of art. Besides this, the fading of some synthetic pigments is causing discussions among conservators of contemporary art due to the fast descolouration of objects and a possible alteration of the artist intention.
Considering these aspects we conducted a survey at the collection of Museum of Contemporary Art, Universidade de São Paulo (MAC USP), aiming to identify all the plastic objects contain organic synthetic pigments and document their conservation state in a condition survey form developed for this purpose. The synthetic organic pigments were identified by Raman spectroscopy, Fourier Transform Infrared spectroscopy (FTIR), Pyrolyses Gaschromatography Mass Spectrometry (Py-GCMS) and X-Ray Diffraction (XRD). In this presentation an overview about the identification of the pigments and the documentation of the conservation state of the objects will be presented, as well as some case studies will be presented and discussed in detail. The selection of the case studies was based on their advanced degradation and on the possible preventive and interventive conservation procedures for the selected objects. In this way, we seek to understand these aging processes and their poetic-visual transformations through two works selected from the collection: “Ci-da-da-ci-da-de-ci” by Erika Steinberger (1970) and “untitled” by Sérgio Romagnolo (1992), and through these analyzes increase the knowledge about its aging, possible deteriorations and consequently to indicate treatment proposals, improving the techniques of preservation of cultural heritage.