print this page

Transparent plastics

The conservation of art works of broken, transparent, unsaturated polyester and polymethyl methacrylate.

Materials and methods were investigated for adhering and filling transparent art works made of unsaturated polyester (UP) and polymethyl methacrylate (PMMA).

Dummy, after treatment.

Dummy, after treatment.

The preservation of transparent plastic art is no easy matter for conservators of modern and contemporary art. There is a lack of literature in the conservation field, especially in the areas of adhesives, filling cracks and reproducing parts that have broken off and become lost.


A method was developed for a conservation approach for objects made of transparent, unsaturated polyester (UP) and polymethyl methacrylate (PMMA). Two transparent artworks from the RCE study collection, one of UP and the other of PMMA, were investigated. Two other works, one by the Dutch artist Mathilde ter Heijne from 1993 from the OCÉ company art collection were yellowed and severely damaged.


The research into the PMMA objects focused on inherent stress, the presence of which can be made visible using a stress-strain viewer. Annealing (heating of the material) can eliminate this stress.


The search for the most suitable adhesive for transparent plastics led to research into the refractive index, suitability and performance of the epoxy adhesives Hxtal NYL-1 and Fynebond, and the acrylic adhesive Paraloid B72. The selected adhesives were tested for applicability on new polyester and on paperweights with embedded objects, which served as naturally aged, yellowed, polyester mock-ups. The tensile strength of the selected adhesive test samples was determined. The epoxy adhesive Fynebond performed best in every aspect.


Fynebond will eventually have to be tested on a polyester study object with a similar size and weight as the two art works requiring conservation. It is possible to restore an object practically to its original state when the method of adhering broken pieces of yellowed transparent polyester is successfully applied. The object can then be appreciated as it was intended. As a result, discussions are under way with the curator of the OCÉ art collection (to which the two Mathilde ter Heijne works belong) as to whether the two works will be conserved.