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  1. #1
    jaimeb82's Avatar
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    Ammonium Dichromate 5% or the other one...

    Beginner here, I am buying tissue renaisance and Ammonium Dichromate. For the Ammonium Dichromate, which one should I buy:

    Ammonium Dichromate 5% Sol. (100ml)
    or
    Ammonium Dichromate (30 grams)

    I am also worried after reading Ammonium Dichromate are cancinogens. Can this stuff fly on the air and stay around my house? Should I mix it outside with open air in a remote location?

    Thanks in advance,

    Jaime.
    "Art is a lie that enables us to tell the truth" -Picasso
    http://www.jaimebermudez.com

  2. #2
    Nicholas Lindan's Avatar
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    I imagine it is a lot cheaper to buy in powder form -- and safer to ship [considering the number of leaking bottles I have unpacked].

    It isn't terribly poisonous - certainly less so than most of the chemicals that are stored under the kitchen sink. Handle with reasonable care.

    By all means mix it outside if it puts your mind at rest.
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  3. #3

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    Well, 30g of dichromate will make you 600 mL of 5% solution.

    In case you didn't know, 5% solution by weight = 5 grams of dichromate plus water to make 100 mL total = 10 grams to make 200 mL, etc.

    Am. Dichromate (and all? Cr(VI) salts) can make you ill. Cr(VI) pollution in groundwater was at issue in the case that the movie "Erin Brockovich" was based on. Gloves are a must, since my understanding is that it can be absorbed through the skin. It is not typically an extremely fine powder (like powdered sugar), more like a fine granulated sugar, but dust can be an issue, so a paper dust mask might be a good idea. Outdoors / remote location, IMO, is overkill, but everyone has their own comfort level, so decide what you're most comfortable with.

    What I do, typically, if the chemical comes in a bottle (and not a paper, foil or plastic packet), and I'm going to use all of it at once, is to add not more than 1/3 to 1/2 the total amount of water into the bottle and re-cap and swirl gently. This takes care of any dust issue. Decant this into your measuring/mixing vessel, and rinse the bottle repeatedly with small amounts of water, dumping in to your mixing vessel (making sure to not go over your total volume). This will ensure you've gotten all of the chemical out. Make sure everything is dissolved in your mixing/measuring vessel, then add water to make up the total desired volume.

    Example, if you're going to make a 5% solution with your 30 grams, then you'll need 600mL total volume. Add ~200 mL to the bottle, gently mix, decant, rinse with 25-50mL each time. Mix everything up and then top off the solution to make 600 mL.

    I would suggest making a stronger solution (10% perhaps), since you may need it if you are using very dense negatives, like with litho film or over-developed pyro or some inkjet methods. You can always dilute a solution, but it's hard to take water back out.

    Since you're talking about renaissance black tissue, I assume you're ordering from Bostick & Sullivan. Last time I ordered dichromate from them, I received about 35 grams. So be sure to weigh the container when you open it, and again after you've rinsed out all the chemical and dried it. The difference will tell you exactly how much dichromate you've received. Be sure to adjust your solution volumes accordingly.

    Lastly, you didn't say where you are, but be sure to check with your local sewer or water authority on what the preferred disposal method should be for excess solution or waste water. Cr(VI), like spent fixer, should never go down the drain.

    I hope that's not too long winded for you Jaime, I just wanted to make sure you had all the info you could possibly want (or more).

    Be sure to download the 1st Ed. of the carbon printing manual from B&S website. Lots of helpful tips in there, too. Check out their carbon printing forum, too.

    --Greg



 

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