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  1. #1
    Athiril's Avatar
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    Hydrogen Peroxide and colour material questions..

    Figure may as well post a thread instead of hassling someone with pm's again.

    I wanted to ask something quickly in response to a thread starting hydrogren peroxide will give black slides in a colour reversal process.. is it because it forms colour through silver after the fact?

    ie: If you take a colour film, develop it, and fix it, then place it in colour developer with hydrogen peroxide added, colour will continue to form through the silver as a mask upon the rate it forms dye?


    I've also seen mentioned use of 3% hydrogen peroxide (supermarket stuff) for added contrast.. and I was wondering if people typically use a whole bottle/couple hundren ml or just a few ml for a noticeable increase in contrast in RA-4 or C-41?

    My google-fu doesn't find any results of how much people are actually using to get a result.

  2. #2

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    I'm yet to try it, but I believe it is a form of calalytic imaging whereby the peroxide serves as a catalyst to form dyes in the presence of silver. So yes, if you BW process a sheet of colour paper and then put it into colour dev + H2O2 it will form dye where there is silver (and continue to do so until you remove the paper or reach Dmax).

    This thread may be of use - PE suggests 10mL/L for boosting contrast...

    Also usable (probably more suitable but harder to find and expensive) is Cobalt Hexammine Chloride a.k.a Hexamminecobalt(III) Chloride (from memory).

    Hopefully there won't be too much for PE to correct here

    Good to see someone else from this part of the world who likes to experiment with colour processes (I just wish I had more time and space for it!)

  3. #3
    Athiril's Avatar
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    Ah thank you very much for that thread I wish I had more time and space too... the only thing I have a large quantity of flexicolor (200l of working developer worth), RA-4 and E-6 CD and CD-2 powder


    I've got 800 ft of 14 year old Vision1 500T in 35mm I've been bulk loading.. experimenting with ways to increase contrast to get a good separation of dmin and dmax and make it good for scanning.. that might help.. and some 19 year old 7245 50D which I plan on shooting on my K3 and developing myself.

    That, and I want to try boosting the colour formation from Rodinal.

  4. #4

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    You may like this thread (photo.net) as well where PE discusses using this process on film... You've got me interested again now too - I need to get some hydrogen peroxide!

  5. #5
    Athiril's Avatar
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    Cheers, I'll check it, its like $4 for 3% 200ml at the supermarket, or like $20-$30 last I checked on ebay for 40-50% 500ml

    "As an afterthought, here is a true maximization process that produces color negs with a push of 400 to 1200 or higher. "

    That's interesting.. I was getting very good pushes with 1+25 rodinal as a first dev with salt added, fixed, bleach and re-developed without peroxide.. I wonder how that'd look with peroxide with even more underexposure for a pushing test.


    Anyway I just shot a roll of Ektacolor 160..loading it in Rodinal 1+100 for an hour with some peroxide.

  6. #6
    Photo Engineer's Avatar
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    The concentrate is very dangerous so be careful.

    Everywhere there is silver metal, dye will form in the presence of color developer + peroxide, so thus in an E6 film where all silver is developed, dye forms everywhere.

    PE

  7. #7
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    Quote Originally Posted by Photo Engineer View Post
    The concentrate is very dangerous so be careful.
    Yes, concentrated hydrogen peroxide can be used as rocket fuel. Can't it?
    Randy S.

    In girum imus nocte et consumimur igni.

    -----

    http://www.flickr.com/photos/randystankey/

  8. #8
    Domin's Avatar
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    That sounds really interesting.

    What is the amount of hydrogen peroxide needed?

    Does Cobalt Hexammine Chloride has some significant advantage over peroxide?

  9. #9
    Photo Engineer's Avatar
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    For peroxide, use 10 ml of 3% per liter of developer.

    For CoHex use 5 g/liter of developer.

    Neither has any advantage over the other except CoHex is harder to get and more expensive. It is also a crystalline solid which will last for years dry.

    PE

  10. #10

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    You can store hydrogen peroxide in a refrigerator to get more life out of it. It's corrosive and will burn your skin when at about 10% and higher.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

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