Having discovered by accident the effect seen here, I set out to reproduce it in order to create this image.
Starting with a #largeformat #Xrayfilm negative of the #tulip I made a contact print onto #cyanotype in gelatine brushed onto watercolour paper. This cyanotype paper had been made several months ago and stored and had, I had thought, been spoiled - already gone blue on its own. However testing showed it could still produce a good image out in the sun for 15 minutes. I developed in a 1% citric acid bath, then oxidised in dilute hydrogen peroxide. This produced some small bubbles with start to lift the gelatine. I then bleached in washing soda which produced larger bubbles and a little more lifting before finally toning on black tea at which point the crazing effect becomes visible. The print is then washed thoroughly and carefully so as not to lift the gelatine too much.
So far I have made 4 images in this way. All available to buy soon (Prices tbc).