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  1. #1
    Mainecoonmaniac's Avatar
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    How toxic are the chemicals for cyanotype?

    I was mixing my second batch of cyanotype emulsion and I was looking for the recipe. I saw a warning about wearing gloves and mask when mixing the solutions of potassium ferricyanide and ferric ammonium citrate. Ferric ammonium citrate is a food additive and I think potassium ferricyanide is not very toxic. So I would think cyanotype chemistry is fairly safe?
    "Photography, like surfing, is an infinite process, a constantly evolving exploration of life."
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  2. #2
    AgX
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    Potassium ferricyanide is used in Germany as anticaking agent in table salt (only). I assume the table salt alone guarantees not to take up too much of the former.

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    According to the National Toxicology Program website of the Department of Health and Human Services potassium ferricyanide is not particulary toxic. They mention a woman who ingested a coffee spoonful or the solid and did not suffer any serious effect. The cyanide ligands seem to be very tightly bound to the iron atom. This chemical was in my first chemistry set. The MSDS does mention that excposure to high heat can release hydrogen cyanide as well as strong acids.
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    dpn
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    Cyanotype, I believe, is pretty darn safe. Mike Ware's new cyanotype formula (which uses Ammonium iron(III) oxalate) is somewhat more toxic. I use a toxic dust respirator (~$20) when working with the powdered components.

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    when the cyanotype is washed ...
    what is that ??

  6. #6
    Mainecoonmaniac's Avatar
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    Thanks! I feel a lot better. Since I don't use Mike Ware's recipe, I'm not going to buy a respirator. I thought cyanotype was fairly safe since they make sun print kits for kids. I didn't know that in Germany, they used potassium ferricyanide as an anti-caking for salt. I'm sure it's safe because the E.U. standards for food safety is much higher than here in the US.
    "Photography, like surfing, is an infinite process, a constantly evolving exploration of life."
    Aaron Chang

  7. #7

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    Just don't heat the ferricyanide above 150 degrees C, or mix it with a strong acid. That would break the bond between the iron and the cyanide and release a cyanide gas. Otherwise they're real safe. I mix the powders regularly without gloves or a mask, I just try not to keep the dust from kicking up too much, and watch my hands when I'm done.

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    Quote Originally Posted by musila View Post
    I just try not to keep the dust from kicking up too much, and watch my hands when I'm done.
    Watch your hands? I guess you'd be in trouble if they start shaking vigorously -- especially if your tongue starts hanging out at the same time!



 

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