Stack Strap Bracket

The Plastics Department of Sunderland University extensively tested the strap. This illustration shows the general arrangement for testing the PET strap around the corner of a brick. Tensile strength tests have concluded that the strength of the strap is maintained when pulled over the corner of a standard house brick. When enough force was exerted to finally break the strap, note that the house brick shows no sign of damage.

The Advanced Materials Research Institute at the Northumbria University extensively tested the strap and the clamp mechanism. Samples of the PET strap and the Zinc plated clamp were placed into a standard neutral salt spray fog (conforms to BS 3900-F12 / ISO 7253: 1992). The components were exposed for 300 hours and assessed for appearance. The images show the PET strap and clamp mechanism after exposure. The PET strap showed a 1% reduction in length, but no weight change. This indicates that it is largely unaffected by the salt environment. The zinc plated clamp showed white corrosion, but more importantly, no red rust except for one or two areas where the coating had been scratched prior to testing This result indicates that the zinc coating provides good protection, and that the clamp would perform well in practice.

Northumbria University concluded that after 9000 hours exposure to direct sunlight, which equates to 15 years in normal conditions, the strap will maintain 81% of its original strength. In the real environment, weather patterns in the UK could extend this figure closer to 20-25 years.