Extreme Velcro

Velcro is a brand name of fabric hook-and-loop fasteners.^[1] It consists of two layers: a “hook” side, which is a piece of fabric covered with tiny hooks, and a “loop” side, which is covered with even smaller and “hairier” loops. When the two sides are pressed together, the hooks catch in the loops and hold the pieces together.^[2] When the layers are separated, the strips make a characteristic “ripping” sound.

But thanks to technology we have the new steel velcro. A square metre of the new fastener, called Metaklett, is capable of supporting 35 tonnes at temperatures up to 800 ºC, claim Josef Mair and colleagues at the Technical University of Munich, Germany. And just like everyday Velcro it can be opened up without specialized tools and used again.

Conventional hook-and-loop fasteners are used for everything from bandages to cable boots in aircraft and securing prosthetic limbs. Mair thinks his spring-steel fastener is tough enough to be used for building facades or car assembly. “A car parked in direct sunlight can reach temperatures of 80 °C, and temperatures of several hundred °C can arise around the exhaust manifold,” he says, but Metaklett should be able to shrug off such extremes.

The fastening is made from perforated steel strips 0.2 millimetres thick, one kind bristling with springy steel brushes and the other sporting jagged spikes.