Today have been on a Cyanotype Photographic Printing day at St Barnabas Press in Cambridge (http://www.stbarnabaspress.co.uk/_about.htm) led by David Chow.
It was after a conversation with Derek at the beginning of the residency when we were talking about the historical use of blueprints in engineering that I explored the possibility of ordering some. It proved impossible to find anyone still making engineering / architectural blueprints (due to large format photocopying and the use of digital files) but the nearest thing is a process called Cyanotype. It can involve using objects directly on a treated surface or creating a digital negative and using that. Exposure comes from the sun or an electric UV light. Its a simple process but also quite complicated at the same time, as there are many variables such as how much chemical solution is loaded onto the paper, the exposure time and so on. It means every printing is unique and hand made.
I wanted to use an image from a CAD file, as these files would never need to be reproduced as blueprints however it does allow for a combination of historical and contemporary practices to converge which is a regular feature of my work.