Lecture 009.007

NAUM GABO’S SCULPTURE ’CONSTRUCTION IN SPACE: CRYSTAL ‘ (1937): EVALUATING A SUITABLE BONDING STRATEGY FOR STRESS LOADED POLY(METHYL METHACRYLATE)
BY ANNA COMIOTTO, MARC EGGER

The study presented here provides the theoretical and experimental basis for repairing a breakage damage on the Poly(methyl methacrylate) (PMMA) sculpture Construction in Space: Crystal, created by Naum Gabo in 1937. To find a suitable bonding strategy, especially to prevent stress crazing and cracking during bonding, different experimental setups were applied. First, stresses present in the sculpture were detected by performing a photoelastic examination and the feasibility of stress releasing by annealing was evaluated. Further, the stress crazing and cracking promoting action of different adhesives was evaluated performing bent-beam tests, whereby different joint geometries and long-term loading were simulated. Finally the breakage damage was documented using photogrammetry. The respective measurement data were used to make physical replicas of the damaged areas of the sculpture. Bonding treatments were applied on these dummies using the acrylic resin Plexigum PQ 611 (dissolved in isooctane) and the load-bearing strength and optical appearance of the adhesive joints were monitored over several months. In the end the bonding operation was carried out in the same manner successfully on the original sculpture. Until this day, three years after bonding the original sculpture, the adhesive joint has kept a sufficiently high mechanical strength and is not affected by craze or crack formation.

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