STICKING TO THE TUBE CHAIR. CONSERVATION TREATMENT FOR A DESIGN CLASSIC IN USE
BY KATHARINA HAIDER, VALENTINA VITALE
Bacon Studios Berlin
The Tube Chair by the Italian designer Joe Colombo is an icon of the late 1960ies foam furniture and has attracted the interest of conservators since more fifteen years. Its manufacturing, composition and preservation was researched by Tim Bechthold: It consists of four PU-coated PVC-tubes with various diameters, fitted at the outside with polyetherpolyurethane foam. The tubes are assembled by three pairs of U-shaped metal clamps with balls on both ends made of the styrene-butadiene-rubber (SBR). Two types of textile seat-covers in a broad range of colours have been in use: LasckinaTM, a Nylon fabric coated with thermoplastic polyesterpolyurethane (TPU), and SoftalonTM, a Nylon fabric that has not been specified further. Replacements for the seat-covers and the balls were available from the manufacturer.
A comparison of seven Tube Chairs with LasckinaTM seat covers has shown that the condition of the PCV-cores, the PU-foam and the fabric of the seat-covers is not critical. The coating of the fabric, however, is often sticky, shows various degrees of a characteristic craquelure and discolorations and is highly sensitive to mechanical stress.
In the present case study a red Tube Chair from a private collection showing differences in manufacture and degradation is presented. Its seat-covers are made of a white fabric with a red coating, whilst on the reference Tube Chair both coating and fabric have a red colour. Infrared spectroscopic analysis of the coating suggests TPU as main component, which is in agreement with previous research. The inner structure of the PVC-tubes exhibits marks of manufacture indicating a modified core or mould. The composition of the rubber balls was identified by Raman-spectroscopy as natural (polyisoprene) rubber.
Although the red coating seems to consist of a material similar to the coatings of other tube chairs, it does not show any craquelure. The surface is sticky and highly sensitive to mechanical stress; sitting on the chair would cause immediate damage. Due to improper packaging and storage parts of the coating were ripped off. Moreover, some seams along the seat-covers are burst open and a clear lacquer, applied to stop the seams form opening further, detached the coating from the fabric.
The planned conservation treatment of the Tube Chair includes the following steps: closing open seams, removing the transparent lacquer, consolidation of loose parts of the coating and filling losses. Since the present copy is not a museum object but will be used, the stabilisation of the red coating seems to be inevitable. Further research is needed to clarify the reasons for the observed differences in manufacture and degradation, and if the present seat-cover is a SoftalonTM type. The possibilities for a protective coating will be researched and tested on a naturally degraded dummy before it may eventually be applied to the Tube Chair.