![]() ![]() ![]() By the mid-20th century, pre-coated diazo paper was normal and easily available. This method uses a photo emulsion coating made from diazonium salt and azo dye. ![]() The "blueprints" where essentially a photo negative copy of the original drawings.Įventually, as time went on, a new process of making architectural/engineering prints using the diazo method. This process creates a print where the background is blue and the areas where the lines of the drawing (black inked lines, normally, on the original vellum drawings) be white. You had to use either an ultra-fine woven fabric or a watercolor paper that will survive the time in water. Then you do the wet development process which often involved a water based wash and then a short period of time in a bath of water mixed with a cap or few caps full of hydrogen peroxide for some extra oxidizing kick and then back in the plain water wash for a maybe 30 seconds or so and then set to dry. This exposure time would be similar to traditional diazo process that used the sun or other UV light source. This process was rather time consuming as you had to coat the paper, wait for it to dry (usually doing something else constructive during that time) and you expose it. Cyanotype used two chemical solutions (potassium ferricyanide and Ammonium Iron (III) Citrate), each dilluted from powder in water (usually distilled water). The old cyanotype during its use was almost always had to be coated on a watercolor paper or similar substrate by the architects/engineers because having the paper pre-coated was not that common in those days. The diazo paper like above is just pre-coated in a factory instead of you having to do it yourself. The process of coating the paper is inherently wet to some degree for both cyanotype and diazo process. It was also known for being a 'wet process' due to the fact that it is developed under water after exposure. This was a different process than the above. This process is technically called "cyanotype". The commonly used terminology "Blueprint" came from an older process of making prints largely for architecture and engineering. To clarify and a little general history of the process and the term "blueprint" and another term for your vocabulary "whiteprint" and this processes. ![]()
0 Comments
Leave a Reply. |