Science News Archive

Sea Pores Over New Defences

German manufacturing giant BASF have developed a new way to protect sea walls from the incessant crashing of the sea - by giving them a holey coating which behaves like a trampoline. The spray-on treatment, which is currently being tested against the ravages of the North Sea on the Island of Sylt, is administered by mixing two chemicals, isocyanate and a polyol. The mixture cures (hardens) in twenty minutes, making it perfect for use between tides. A high pressure spray can then be used to apply the mixture to stone surfaces, or it can be mixed with loose stones and sprayed in layers upto 30cm thick. But it's not a solid layer. The surface is punctuated with large pores a few centimetres across. When a wave slams into the surface some of the energy is dissipated by the natural elasticity of the material. But even more is mopped up by the pores as sea water tries to force its way through, turning destructive wave energy into heat and noise. According to project leader Marcus Leberfinger a wall reinforced with the coating has "reliably withstood the huge impact of the waves during this past storm season". Apparently the porous plastic is also proving popular with wildlife, with the holes making ideal homes for crabs, limpets and plants.

13th May 2006