Degradation of polyurethane (PUR) elastomers: research into properties, degradation and conservation treatments.
The composition and the ageing behaviour of PUR-elastomeric objects produced by an artist were compared to that of industrially manufactured design objects.
Hella Jongerius SoftVase, Droog, 1994, soft polyurethane vase.
Polyurethane (PUR) elastomers were developed around 1940 in Germany. They are rubber-like materials made of various components with different properties, which can be cast into virtually any shape.
Due to their versatility, ease of working and high availability, PUR elastomers are currently very popular among designers and artists. Consequently they have a large presence in museum collections.
PUR elastomers occur as a PUR ester and as a PUR ether. The condition of an object of a PUR elastomer depends on various internal and external factors. Externally an object can be exposed to high humidity and light; a fault in the fabrication process is one internal factor that can affect the durability of an object. PUR esters are sensitive to humidity due to hydrolysis reactions, while the PUR ethers react with oxygen through photo-oxidation reactions.
Objects produced by artists were compared with factory-made design objects of PUR elastomers on two aspects: composition and ageing behaviour. Why do Cecchini's objects of the Stage Evidence series present chemical and physical changes after only 10 years while Soft Vase by Hella Jongerius does not?
Interviews with the assistants of Loris Cecchini and Hella Jongerius revealed that it is quite usual to use various production processes for making art works and design objects. Finestre II and all the Stage Evidence series were handmade by the artist in the studio, while Herikon, a company specializing in the production of PUR elastomer objects, manufactured the Soft Vase.
Using artificial ageing tests it was possible to mimic reproduce the liquefying of the PUR ester elastomer, as well as changes in elasticity as in Cecchini's Finestre II. The results of the FTIR and Py-GC-MS analysis, the artificial ageing, and mechanical tests show that the difference in behaviour is not due to a faulty fabrication process, but is inherent to the components of the PUR elastomer.
The results of the first adhesion tests with PUR ether elastomers were satisfactory. Further research will include additional tests for adhering PUR ether as well as PUR ester elastomers. The best performing adhesives will be applied to the original Soft Vase.