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  1. #1
    Mateo's Avatar
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    Chemisty help for Uranotypes

    I'm still figuring some things out printing with Uranium and one thing is bothering me in particular. The images tend to want to bleed unless washed in slightly acidic water (<1% citric acid). After that they get a rinse in distilled water but I worry that the final prints will still be acidic. I'm hoping that someone out there could help me understand why they bleed and why the acid would help.

    Tween 20 helps but doesn't cure the problem and oddly 1% PVA seems to help as well. I ain't smart enough to figure this one out so would greatly appreciate any suggestions from those with experience in any of the alt processes. Thanks.

  2. #2

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    Quote Originally Posted by Mateo
    I'm still figuring some things out printing with Uranium and one thing is bothering me in particular. The images tend to want to bleed unless washed in slightly acidic water (<1% citric acid). After that they get a rinse in distilled water but I worry that the final prints will still be acidic. I'm hoping that someone out there could help me understand why they bleed and why the acid would help.

    Tween 20 helps but doesn't cure the problem and oddly 1% PVA seems to help as well. I ain't smart enough to figure this one out so would greatly appreciate any suggestions from those with experience in any of the alt processes. Thanks.
    You might want to do a search on the alt-photo-process archives. There are a couple of people on that list who have done uranium printng, including a fellow named Bob Schram. http://www.usask.ca/lists/alt-photo-process/

    Sandy

  3. #3
    Mateo's Avatar
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    Thank you Sandy for the reply. About a year ago I did contact Mr. Schramm and he was very helpful. But beyond the basics I think I'm on my own. I guess I'm hoping someone might understand what's going on regarding the bleeding. I have seen this happen with Cyanotypes but didn't bother any further with them to figure it out. My best guess is that the sensitizer isn't embedded in the paper fibers and is simply washing away. Perhaps if someone could explain why Platinum sensitizer doesn't wash off then maybe it would be easier to figure out where to go next.

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    Mathew, I am going to take a stab at it, but bear in mind I know nothing about Uranotypes, so take my comments in this light.

    When you do the wash, is this with destilled water or is it water from the faucet? If it happens when you do a wash with faucet water, then most likely there is a component in the water that is causing this. Perhaps is a little high pH (it makes the water taste "sweeter"), perhaps it is the chlorine or fluoride they add, who knows? It is just like pt/pd and pd prints, an HCL clearing bath will not bleach a pt/pd print, but it can with a pure pd print, this is just the chemistry of the water and the interaction with the water components.

    If you have hard water, maybe the calcium carbonate is what is causing a high pH and removing your sensitizer.

    I guess what I am trying to say is, identify the "type" of water causing you this problem and go from there.

  5. #5
    Mateo's Avatar
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    So Jorge,

    Do you ever use a PH meter with the processes you try? Or would that be just a waste of time and money?

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    Quote Originally Posted by Mateo
    So Jorge,

    Do you ever use a PH meter with the processes you try? Or would that be just a waste of time and money?
    Nope.....but that does not mean I would not use one if I found myself in the same situation. I would not buy a pH meter, get test strips first, there are some that can read between pH 6, to Ph 8. So what I would do is test the pH of the water with the test strip (it should not be below 6 or above 8 for drinking out of the faucet water) if the pH is above 7, adjust the pH to 7 and see if the problem continues, if it does not then there is your answer. If it does, then is is not the water but most likely a "natural" behavior of uranotypes that requires lower pH to "fix".

    It just occured to me that perhaps it can also be the paper and the sizing, have you tried doing a pre oxalic acid bath? this might also be an answer. Who knows, maybe Uranotypes need an acid medium to "fix" properly.

  7. #7
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    considering the flouride that is in the tap water is from the slurry the scrubbers in aluminium plants collect, it has many more things in it than just flouride. Go for the distilled water. Beyond that I don't know a darn thing about this process. Just going by what Jorge was looking at.
    Non Digital Diva

  8. #8
    Mateo's Avatar
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    Ya I'm going to call Tri-Ess tomorrow and get some strips.

    Aggie,
    The city I live in wasn't sure if my toothpaste had enough flouride so now I have to let the water for my trees sit out overnight before using it. NO way am I drinking it.

  9. #9
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    Check the B&S site and forum lots of info on that
    http://www.bostick-sullivan.com/Tech...s/formular.htm
    Gustavo Castilla
    We are not moved by things ,
    but by the views we take of them.
    Epictitus.
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