Is my cyanotype done exposing yet?

I'm trying to expose my first cyanotypes this morning.

I used the Photographer's Formulary liquid preparation. They are exposing on top of a cutting board with a piece of glass on top of the whole sandwich, in my apartment next to a window. It's a cloudy day and we're expecting snow.

I waited about an hour this morning and then I had to go to work, so I just left it there. It will end up having hours and hours of exposure.

But by the time I left there wasn't the slightest change in the color of the dried coating elsewhere on the paper.

So my questions are -- how long should I expect these exposures to take under these conditions? Can I use the coated margins of the paper as a decent indicator? If I end up really overexposing these, can I bleach back some contrast? And finally, if I've coated the paper excessively will that make it take longer?

Thanks.

Paul,

No one can say how long it would take "under these conditions", but it probably wont expose. Even Cyano has reciprocity. I would venture a guess that too much if not all of the uv is taken by the clouds. The next thing is the window, it could have a uv coating and third, your glass plate could have a uv rating and block most of the uv coming in. Many things that need to be checked.

I would really recommend that you try something like this in good conditions for the first try. You have several variables that would make it close to impossible to "debug".

As for over exposure, yes, there are methods that can be employed to reduce the iron in the print. I have not done any of these processes as of yet, so I will defer to someone else who may have done such.

As to the coating, again, you have too many variables to say, but an [excessive] coating could cause a very heavy print.

Give it another try on a good sunny day, outside, if at all possible.

Best of luck.

In most cases a good exposure for cyanotype from a negative matched to the expsure scale of the paper will have the deepest shadow areas of the print undergoing a tonal reversal (i.e., true solarization) and becoming lighter. The emulsion goes from a greenish yellow color to a powder blue-white as the solarization occurs.

Try again with sun. In bright California sunlight, I usually see the shadows reverse (go from light green to blue to olive drab) within 15 minutes tops. On an overcast day, I think we gave up after an hour.
Try it again! Its a fun and simple process.