no 206 152 now u s pat no 4 911 766 by the assignee of this invention this application discloses a method for refining the domain wall spacing of final texture annealed grain oriented silicon steel by applying a phosphorus contaminate to a pattern of exposed steel being free of thermal and plastic stresses the phosphorus striping process includes phosphorus vapor being generated at or near the strip surface for example by hydrogen reduction of a phosphate coating the phosphorus migrates to any exposed iron such as the metal stripes attacks the iron and forms wedge shaped phosphide particles the forsterite is protective and is not attacked composition was applied either directly to the abraded strips or to similar un abraded dummy strips ______________________________________ 34 p 34 coatingphosphoric acid 118 gm 1magnesium oxide 18 gm 1ammonium hydroxide 58 20 gm 1chromium dioxide 34 gm 1dupanol 2 1 gm 1water balance______________________________________ the coated metal strip samples were air dried for 1 minute at 800 u00b0 1475 u00b0 f 427 u00b0 802 u00b0 c total coating thickness both sides was about 0 1 mil strips were assembled in one of two ways for the phosphorus stripe operation in one case the abraded strips to which the phosphate coating had been applied the procedure consisted simply of stacking the strips one on top of another for un coated abraded.