Metal foams can be made by first making an open-cell polymer foam, then embedding this in plaster, burning out the polymer and finally forcing metal under pressure into the resulting mould to replicate the foam. If the cell walls of the polymer foam are cylindrical with a diameter of is 0.5 mm, what pressure will be needed to replicated it using a zinc die-casting alloy? The surface tension of the zinc alloy is 0.76 J/m2.