I also did not find a solution to this, and would very much like to know.
We created some beautiful unprocessed prints outside, alongside the cyanotypes, of simple things such as hand prints and the such. I think the paper reacted to moisture and maybe sweat (and salts) from the students palms and fingers and created super detailed prints of all the lines on their hands. They were in a beautiful purple hazy color, and are now steadily breaking down into dark brown/ dark purple, and the details are fading.
In hindsight we should have just rephotographed them to record some semblance of the original, but the idea of an art piece with a finite time for viewing and gradual decomposition is also quite interesting.