A P-Fe-Co alloy is deposited on a non-metallic, e.g. plastics, substrate by applying an adhesive coating to the substrate, treating it with a catalytic solution of a compound of a metal selected from Pd, Pt, Ir or Au, reducing at least some of the compound to the metal, and then depositing the alloy from an electroless solution which may comprise cobalt sulphate 20 to 40 g./1., ammonium sulphate 40 to 80 g./1., Rochelle salt 100 to 600 g./1., sodium hypophosphite 10 to 30 g./1., solution, and ferrous ammonium sulphate in a minor amount. The pH is 7.6 to 8.0. An apparatus for continuously coating a film is described (see The Figure not shown) the parts of which are made of non-metallic material or stainless steel. The alloy coating may be Co 90%, Fe 5.4%, P 4.6%.