Real blueprints are actually blue (various from a purplish colour to a really deep blue), with whitish lines and letters. The unique blueprints were made by a moist process called cyanotype, but later a dry” course of, called the diazo process, was developed. Real blueprints haven’t been the usual for a while now; Ewan says he is by no means actually made blueprints himself, however colleagues of his remembered doing it.

For a long time, bluelines have been a budget possibility for copies. The process was easy, the machines were low cost and didn’t need much upkeep, and the paper was in high demand. About 2006, ammonia started being regulated as a hazardous substance (would that we could regulate out of existence what makes diapers smell of ammonia….) Suddenly, one needed a hazmat license to ship ammonia, and the transport prices elevated to about double the cost of truly making …