(57) The stencils (resists) currently employed in sand-blasting engraving techniques, for example of glass, are relatively flimsy, and thus it is easy to over-engrave and so to spoil the article being worked upon. In addition, the paper backing onto which the resist layer is applied is invariably uncoloured, and this makes it too easy to mistake the paper for engraved glass or vice versa, adding to the difficulties of performing the engraving process correctly.
The present invention provides a resist the backing sheet of which is of a strong colour that contrasts with the colour of the surface to be engraved when thus engraved. The backing sheet preferably also contrasts with the colour of the resist layer itself, and is advantageously of a heavy-weight pre-gummed paper wherein the adhesive gum is provided in spaced particulate form.