Following from Parts One (preparation) and Two (set-up and exposing) this final part details finishing the exposure and developing the image.
Ending the Exposure
Choosing when to finish an exposure depends on artistic choices such as the desired colour and level of detail in the final image. See Part Two for more details. In these images detail was desired. This necessitated an exposure time of around 3 days in variable conditions from full, strong sunshine to borderline rain.
Hellebore
The idea here was to produce a ‘soft’ image, but with sharp detail of veins within the petals. This flower was originally dark purple / black.




Once exposed, development is simple – wash the image in tap water until you reach a level of development you are happy with! At a minimum, images should be developed until all unused chemical is removed. This is easiest to see where paper may still be more-or-less unexposed, such as on the overlapping areas of petals, above. The paper should be washed until these areas return to the original colour of the paper. Top left shows development after a minute or so; bottom left shows my choice of ‘full’ development / completed washing for this image. Washing these images was done for around an hour, with multiple changes of water. Most of the chemical was removed within the first 5 – 10 minutes, after that it becomes aesthetic preference. I have washed images for up to 18 hours when needed.
Extending the washing time can alter images to the better but, again, this will be an artistic choice of when to stop. Delicate areas will fade and possibly disappear during long washing.
Finally, it is often suggested that an oxidizer such as hydrogen peroxide is added to the water to ‘finish development’. This is a fallacy and unnecessary. The image will acquire it’s final colour to exactly the same extent once fully dried.
The final image here is pleasing and is close to what was intended. It has a certain ‘softness’ which reflects the subject’s dusky, matt character, and it has detail. It is an abstraction, one interpretation of this subject.
Silver Birch (Copse)
This image was made partly to serve as an exposure guide to the larger image, but also for it’s own sake. As above, detail in leaf structure was sought in the final image.




Silver Birch, Kindergarten
Based on the smaller exposure of Silver Birch leaves, it was decided to stop this exposure at the same time, as similar detail was hoped for.





Such is the unexpected fun and experimentally-acquired beauty of cyanotype printing! The final image is, despite the lack of detail, aesthetically very pleasing and will make a good framed print. Now to choose the next subject…


If you still have questions, or would like more details about specific images, please feel free to get in touch.