Bed letters are produced on glass by a sand-blast process. The glass used for this purpose is known as ruby flashed glass. The letters that are to be produced are first cut out in paper. These paper letters are coated with a resist or protective covering composed of 1 part of ordinary hot glue and 1 part of glycerine, mixed together. The letters are then pasted on the glass, the resist side outwards, and the glass is then ready for blasting. The sand cuts away the unprotected surface of the glass, the resist protects the paper letters, and, when these are washed off the glass, red transparent letters will be shown on a white opaque ground.