Development Of An Etching Paste Based On Fry'S Reagent

The present work reports the development of a paste containing Fry's reagent (a CuCl2 solution in HCl) and bentonite that can be used to restore engraved marks on iron and steel surfaces. The efficiency as an etching reagent is similar than that reported for the liquid Fry's solution. The ease of using this paste gives distinct advantages over the liquid reagent, such as avoiding acid solution spoilage during etching by technicians and police experts. The work is completed with a morphological study of the metallic surface after the procedure by electron microscopy. The surface is not altered by the applications of the reagent. This paste is currently used by police staff in Uruguay.