Since their introduction in the twentieth century, unsaturated polyester and acrylic plastics (polymethyl methacrylates) have become increasingly popular with artists and designers for their versatility, optical properties, and ability to be shaped and colored. Initially frowned upon for art, these plastics are now ubiquitous in art and design collections.

For conservators, plastics entail a whole new set of challenges. Objects made of polyester or acrylic plastics often have smooth and seamless surfaces, which are easily harmed and tolerate very little damage: the smallest scratch can be so conspicuous that it affects the entire perception of the artwork, especially if the piece is transparent or translucent. In addition, selecting suitable conservation materials and methods to repair mechanical damage—such as scratches, abrasions, cracks, chips, and broken parts—is difficult. Many factors must be considered. For example, adhesives that contain solvents or produce heat during curing can damage plastics or cause alterations such as stress crazing. Repair materials often have compositions similar to the original plastics, making reversibility a challenge; for this reason, their behavior upon aging is an especially crucial factor to consider. Moreover, making repairs invisible is as difficult for transparent plastic objects as it is for broken glass. Because of their low tolerance for damage and the difficulty of achieving inconspicuous local repairs, damaged polyester and acrylic objects often undergo very invasive treatments, such as extensive re-sanding, or partial—and, in extreme cases, total—refabrication.

As part of its Modern and Contemporary Art Research Initiative, the Getty Conservation Institute (GCI) began its Art in L.A. project to study art, including works in plastic, created in 1960s and 1970s Los Angeles by "Finish Fetish"; artists, and to highlight the conservation issues.1 The GCI exhibition From Start to Finish: De Wain Valentine's Gray Column explored the dilemma surrounding the conservation of Valentine's massive work: Should the surface be re-sanded to reflect the artist's intent, bringing it closer to the original aesthetic concept, or should it be preserved with its original toolmarks and the signs of the passage of time? Over the years, many Finish Fetish works have been "refinished"; or "resurfaced,"; treatment that entails removal of significant quantities of original material.2

An important objective of the GCI project is therefore to investigate less invasive repair methods for polyester and acrylic objects, with the goal of providing conservators a wider range of options than currently available. Besides GCI Science staff, the project team includes Anna Laganà,3 a private conservator, and John Griswold, a private practitioner who also serves as the Norton Simon Museum's conservator. The project specifically explores additive methods—as opposed to subtractive methods like sanding or polishing—to mitigate the visual impact of scratches and abrasions, as well as methods to repair chips and losses.

Pristine-looking polyester mock-ups (pigmented and unpigmented and with different thicknesses) were prepared by Eric Johnson, a Los Angeles–based artist working in polyester, and acrylic test samples were purchased from a local company. These were then damaged in various ways, including deep scratches, webs of superficial scratches, chips, and large losses. Researchers tested different treatments on the mock-ups and acrylic samples, utilizing both traditional and novel methodologies, and the results were analyzed and compared.

Several methods were explored to fill deep scratches and chips with a variety of instruments such as small brushes and needles. Resaturating the surface by applying coatings on large abraded and scratched areas was also investigated. To fill in losses, direct and indirect casting techniques (generally derived from glass conservation) were tested. The materials for filling and casting were selected based on their refractive indexes, as well as on their transparency, low viscosity, compatibility with the original materials, and aging properties.

In collaboration with several commercial companies, 3-D scanning and printing technologies were also explored as possible rapid and high-precision methods to reproduce missing parts or produce molds for missing parts without direct contact with the object. Avoiding contact would be especially useful in treating very fragile works. The application of 3-D printing for conservation is in its early stages, and costs currently can be prohibitive; however, techniques improve every day, and the technology is extremely promising.

The suitability and stability of the materials and methods used for such repairs were evaluated in GCI laboratories using a wide range of instruments and techniques. The initial results are encouraging, as they showed the potential of using additive methods to mitigate the visual impact of scratches, abrasions, chips, and losses in transparent cast polyester objects. Details of the research will be presented during the International Council of Museums—Committee for Conservation (ICOM-CC) 17th Triennial Conference in Melbourne and published with conference preprints. Meanwhile, the project continues. The materials and techniques providing the best results will be used on case studies of original fragments, rejects, and deaccessioned works of art gathered as part of the Art in L.A. project.

It is hoped that this research will help increase the range of options for conservators to repair art and design objects made of plastic. Instead of having to choose between preserving the original materials and re-creating the original intended appearance— an irreversible action, when materials are removed—conservators may employ additive repair techniques to achieve a more satisfactory outcome.

Anna Laganà is a private conservator based in the Netherlands. Rachel Rivenc is an assistant scientist at the GCI.

1. Rachel Rivenc, Emma Richardson, and Tom Learner, "The LA Look from Start to Finish: Materials, Processes and Conservation of Works by the Finish Fetish Artists,"; in ICOM-CC, Preprints of ICOM-CC 16th Triennial Conference, Lisbon, 19–23 September 2011 (Portugal: Critério – Produção Gráfica, Lda., 2011). For an overall description of the project, see getty.edu/conservation/our_projects/science/art_LA/.
2. Tom Learner, Rachel Rivenc, and Emma Richardson, From Start to Finish: De Wain Valentine's Gray Column (Los Angeles: Getty Conservation Institute, 2011).
3. Anna Laganà and Thea B. van Oosten, "Back to Transparency, Back to Life: Research into the Restoration of Broken Transparent Unsaturated Polyester and Poly(methyl Methacrylate) Works of Art,"; in ICOM-CC, Preprints of ICOM-CC 16th Triennial Conference; Thea van Oosten and Anna Laganá, "Mending Broken Pieces: Research into Methods and Materials for Adhering Broken Unsaturated Polyester Artworks,"; in Future Talks 009: The Conservation of Modern Materials in Applied Arts and Design, edited by Tim Bechthold (Munich: Die Neue Sammlung, The International Design Museum, 2011), 70–77.