https://calendar.dallasmakerspace.org/events/view/23518
New cyanotype class! We’ll learn everything from mixing our own solutions, editing files in photoshop, and exposing our images with negatives. See you in class!
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Love to see new classes being developed especially ones with some connection to chemistry. Excited to see how this turns out.
I also just wanted to check with you to confirm that you are using a formulation without hexavalent chromium. I know that the traditional formulation uses potassium dichromate which is probably a bit nastier than we want to do at DMS.
As far as I am aware the original recipe only called for a soultion of Potassium ferricyanide
Ferric ammonium citrate. We wont be fixing or toning in this class.
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Ahh okay, if you aren’t doing a fixing step then everything should be fine. The dichromate is typically used for that. The chemicals you listed are not considered hazardous.
More Info: https://www.cdc.gov/niosh/hhe/reports/pdfs/81-171-880.pdf
You’re referring to Wares “New” Cyanotype formula which uses a very very small amount of potassium dichromate as a contrast agent. The traditional formula only uses Potassium Ferricyanide and Ferric Ammonium Citrate. Also you don’t fix a cyanotype so much as you just make sure to wash out all the unexposed solution so it doesn’t further develop to UV light.
If you do notice a cyanotype fading due to excessive direct UV, you can place it in a dark place until it restores. Though my own cyanotype a have been hanging for 12-15 years in various spots and I’ve not really noticed any fading (I would guess ppl that do notice fading are hanging them in places like gallery windows with direct sun for years)
My impression was that the potassium dichromate step was a standard part of the process until about the 1980s but I’m not that familiar with the history of cyanotype as used in art.
I was also using “fixer” colloquially rather than in a more technical sense. I understand that a photographic fixer is a chemical process that both stabilizes the image and removes the unexposed photosensitive compound (but dichromate is only for stabilization). While it might not be perfectly accurate, I’m using the term in the same sense that NIOSH/OSHA used it to describe that process step.
From the NIOSH report I linked earlier:
Recommendations: 1. Discontinue work with the cyanotype process, or discontinue use of potassium dichromate as a fixer