Treatment Strategies for Objects Made of Cellulose Esters

A component of Preservation of Plastics
People look closely at objects laid out on a table and a reference sheet

This research addresses the urgent need for treatment strategies in conservation of objects and works of art made from cellulose acetate (CA) and cellulose nitrate (CN).

Cellulose acetate and cellulose nitrate have been used to produce a large variety of artifacts thanks to their versatility and transparency. They are transparent like glass but with the advantage of being flexible, reshapeable, and lightweight. They can be molded, shaped, and carved and made into any color or pattern. They even have different grades of hardness depending on the plasticizers used.

Their introduction revolutionized not only the commercial marketplace but also the fine art field, as they gave a new dimension to artists' techniques. They were the first plastic materials to be used by artists; among the best-known works of art made with these materials are the modernist sculptures by Constructivist artists Naum Gabo and Antoine Pevsner.

Many works made with CA and CN are considered iconic artworks and artifacts of the 20th century; however, some of these pieces also gained notoriety as examples of the degradation of these early plastics. A dramatic example of this is the deterioration that occurred to several sculptures by Naum Gabo in Tate’s collection (see Related section).

Cellulose acetate and cellulose nitrate have proven to be inherently unstable due to their poorly stabilized and largely experimental formulations and are among the four plastics that deteriorate most rapidly in museum collections. One of the results of their chemical degradation is the production of acid gasses that can cause the autocatalytic breakdown of these polymers. At present, the risk of losing a significant part of our cultural heritage is very high; objects from art, design, fashion, and historical collections have literally disintegrated, and many others are currently in poor condition.

Since the 1990s, conservators and scientists have been pointing out the urgency of establishing treatments to conserve degraded cellulose acetate and cellulose nitrate. However, to date there have been no viable solutions.

Recognizing the urgency, this research component focuses on investigating materials and methods to stabilize, consolidate, and protect degraded objects made with these cellulose esters plastics in order to minimize damage and extend the lifetime of these works.

The research strategy includes:

  • examining and investigating CA and CN objects from different museum collections showing instability
  • testing treatment options on test samples and degraded study objects in the Plastics Reference Collection and on deaccessioned artifacts
  • evaluating a treatment’s effectiveness and suitability via combined scientific
  • testing and visual assessment

To assess research goals, the project team has been collaborating with experts in the scientific field, museums, and the Getty Research Institute.

A large collection of combs containing CA and CN, part of the Research Institute’s Harald Szeemann Archive, served as a case study. A selection of these combs was featured in Szeemann's historic 1974 exhibition Grandfather: A Pioneer Like Us and in the Research Institute’s 2018 Harald Szeemann: Museum of Obsessions exhibition on the life and work of the renowned Swiss curator.

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