Post-rinse cyanotype exposure stain

[chloe_w]

I've been getting into cyanotype over the last year, and have had issues with some (not all) of my cyanotypes developing a brownish/yellow stain after washing and fully drying, when they are then exposed to sunlight again. best guess is it's iron, but still unsure of how to fix it. I'm not sure what the cause is, I rinse thoroughly (until the water runs clear), and let them develop and dry in the dark. I've been using citric acid during the initial rinse to develop the color, could that be the cause? or maybe my water is too hard? Thanks so much!

chloe

 

[koraks]

Welcome to Photrio, @chloe_w !
What kind of paper(s) are you printing on? Some papers will work better than others. Sometimes, it helps to acidify the paper: soak for a few minutes in a weak solution of acid (e.g. citric) and then let dry. This removes the alkaline buffer that can interfere with the printing process.

Hard water can be dealt with by adding a pinch of citric acid to it. It only takes a tiny bet to entirely offset the water's hardness.

Perhaps you could post a photo of an affected print; people might be able to comment more specifically if they recognize the problem..