At last, I am seeing some progress. Starting with fresh mixes of the potassium ferric cyanide and the hydrogen peroxide and going to using 2 digital negatives for each image, I have ramped up the exposure to UVA to 6 mins and that seems to have done the trick. I am quite pleased with these prints:
These are the images I took to record the process:
Having seen the work L’autre rive of Émeric Lhuisset which I first saw on Catherine Bank’s blog, I am now investigating making cyanotypes bigger than A4 which means I have to find a company which sells A3 or even A0 transparency sheets = very exciting!