New bleach bath (non-toxic)?

Discussion in 'B&W: Film, Paper, Chemistry' started by Alessandro Serrao, Dec 6, 2004.

  1. Alessandro Serrao

    Alessandro Serrao Member

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    Wandering on the net I've stumbled across the following site http://www.a1.nl/phomepag/markerink/hieslide.htm.
    Very interested I saw that cupric sulphate is used instead of KMnO4 or K2Cr2O7.
    Is this possible, or anyone of you have tried this?
    Although the intended formula is for Hie film only, would it be possible to develop normal b&w negatives to obtain slides?
    Using Cupric Sulphate would be beneficial instead the very poisonous Potassium Dichromate or even the Potassium Permanganate.
    Any hints?
     
  2. Jorge

    Jorge Inactive

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    I would rather go with permanganate or the dichromate than having 98% sulfuric acid in my darkroom. Can the belach work, sure, it will work fine. I dont know how good as far as grain it would be, but it will bleach the film.
     
  3. Alessandro Serrao

    Alessandro Serrao Member

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    How can you say this? Dichromate is a know carcinogenic and here in Italy permanganate is forbidden to buy.
    Plus, on every recipe I've seen, one must always use a 10% solution of sulphuric acid, either with dichromate or permanganate so using these two chemicals doesn't automatically imply the non-use of the sulphuric acid.
    I missed your point.
     
  4. Ole

    Ole Moderator Staff Member Moderator

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    Variation A can be made with 200ml 10% sulfuric acid. Use 800ml water, of course.

    Variation B uses 50g potassium bisulfate instead, so no nasty acid.

    Variation C, see A.

    Copper sulfate bleaches work just fine, q.v. Tim Rudman's toning book.
     
  5. Jorge

    Jorge Inactive

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    Yep, you missed the point. Sulfuric acid, at 98% is a very dangerous liquid to have around, even a small drop will immediately burn your skin. Dichrromates and permanganates, being solids are much more easier to manage and control in case of an accident. Spills are easily contained and if a drop or two fall on you, nothing will happen.
    As I have said many times in this forum, there is no such thing as "bad stuff". It is only the person who uses it or missuse the chemicals that make them bad. If you are in the habit of mixing dichromates or permanganates without porper ventilation, if you spill some and leave it while you do something else and keep breathing it, etc, etc. Well yeah, you will most likely get sick.

    If, OTOH you take proper precautions, these are no more dangerous than any other chemical. I suspect you cannot buy permanganates in Italy because they are good bomb ingredients, not because they are so toxic.

    IMO, an accident with 98% suslfuric acid is far more dangerous than spilling or dropping a bottle of dichromate which I can clean right away.
     
  6. gainer

    gainer Subscriber

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    Anyway, who said copper sulphate is non-toxic? I don't want any in my mouth.
     
  7. Norman Christie

    Norman Christie Member

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    Could this bleach (variation b) be used in lith printing. Sulphuric acid is very difficult to get.
     
  8. Alessandro Serrao

    Alessandro Serrao Member

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    Yes I've tried it and I guaranteed you that it doesn't work.
     
  9. Photo Engineer

    Photo Engineer Subscriber

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    Cupric Sulfate is a well known bleach for films. There are many patents on it in the literature. I have worked with it myself. The problems are threefold; the first is that the bleach will not work if there is not enough acid, and the second is that the copper salts can stain the film or paper and cannot be removed and the third is that these bleaches are very slow in most cases. There are also blix formulas.

    Concentrated sulfuric acid (Oleum) is pretty much unobtainable. You can get dilute sulfuric acid at auto stores (about 37%) and from the Formulary (about 48%). The 48% is the highest that can be shipped now in the US without a special license.

    A drop of oleum on the skin does not cause immediate burns due to lack of water. It needs water to react. So, immediately start a huge flow of cold water in the nearest tap and wash it off as quickly as possible with as much water as possible. Do not leave it on the skin for over 30". When you wash it off, you will feel an instant burning sensation and a lot of heat, as the reaction starts. If you wash with enough water, fast enough, no harm will be done in most cases. Once rinsed well, put some sodium bicarbonate on the affected area for about 1/2 minute and then re-rinse in cold water. If the skin is broken, call a doctor or go to emergency immediately. Do not get it in the eyes.

    PE
     
  10. jim appleyard

    jim appleyard Member

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    PE, just curious, but what if you put sod bicarb on first, w/o water? Wouldn't that serve to "neutralize" the sulfuric acid, at least to some degree? Then wash after the sod bicarb has done what it can?
     
  11. Photo Engineer

    Photo Engineer Subscriber

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    Jim;

    No, it would not. In fact, it is the worst thing to do. You end up adding heat and water to a mixture that needs both to harm skin! So, adding bicarbonate is the last thing you want to do before you wash it off.

    PE
     
  12. Kirk Keyes

    Kirk Keyes Member

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    I knew someone that used the same reasoning as Jim and put some soda ash on the sulfuric. He got a very bad burn from it.

    Sulfuric is hygroscopic and will pull water from your skin or other organic compounds. It does take a little time for the reaction to get going - you'll know when you get it on you and hopefully it will give you some time to wash it off.

    Add a little sulfuric to a little sugar and see how it reacts strongly - the sugar is dehydrated and the reaction leaves only carbon behind. It's quite impressive - see this video here: http://www.youtube.com/watch?v=uaB70TgLfqs
     
  13. jim appleyard

    jim appleyard Member

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    Gentlemen, thank you. You learn something, or should learn something every day!
     
  14. Ole

    Ole Moderator Staff Member Moderator

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    Not a good idea at all.

    Mixing a concentrated acid with bicarbonate shouldn't be done anywhere near skin - not only does it effervesce spreading acid around, but it's also exothermic enough that (heat) burns are a real risk in addition to the acid burns!

    -----

    this was a belated reply to Jim's question - for some reason it took a long while from i pressed "post" until it was actually posted.
     
    Last edited by a moderator: Feb 11, 2008
  15. Alessandro Serrao

    Alessandro Serrao Member

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    I remember it didn't work at all (variation a). Someone suggested to put some NaCl in it. Dunno why.
     
  16. Photo Engineer

    Photo Engineer Subscriber

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    Cant help you at all. I have used them, they worked, but they were very slow in the experiments I ran. The solutions that I used were pale blue-green.

    PE
     
  17. Photo Engineer

    Photo Engineer Subscriber

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    I would like to add that anyone calling a mixture of cupric sulfate and sulfuric acid "non toxic" is fooling themselves. Also, make sure that if you do try to make up this bleach that you use the cupric sulfate and not cuprous sulfate. Cuprous sulfate will not work at all.

    PE
     
  18. Alessandro Serrao

    Alessandro Serrao Member

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    I did use cupric sulfate as used in gardening.
     
  19. tim rudman

    tim rudman Member

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    I've just come to this a bit late, but yes and no. You can use a cupric sulphate bleach with spectacular results for print redevelopment in lith (if that's what you meant?) but you need a halide. Sodium chloride (pure, not table salt) is ideal.
    Conc sulphuric acid is typically 96 -98%. The Photog' Formualary sulphuric acid is 48%. Adding double the amount of this works fine. This is what we use on my workshops there.
    If you need the formula I can provide - but it is in most of my books.
    Tim
     
  20. nick mulder

    nick mulder Subscriber

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    hmmm,

    maybe I'm lucky in NZ - got both %98 sulphuric acid (almost gloopy in consistency) and Pot Dichromate from the same supplier ... Pretty cheap too.

    I've spilled it once and that was on purpose to see its effects, cleaned up a small spot on the concrete garage floor :wink: - I use gloves, googles with and a mask when using the powders, also tend to do it when someone else is in the house in case I incapacitate myself somehow (unlikely though)
     
  21. Photo Engineer

    Photo Engineer Subscriber

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    Oleum, the gloopy stuff is thick like glycerine. Don't add water to it, add it to water. The only exception is when you are removing it from yourself. It must be washed away as rapidly as possible with as much water as possible. Don't step on the spot on the floor until you neutralize it with bicarbonate of soda. I saw a guy do that once and he ate a hole through his shoe.

    PE
     
  22. dancqu

    dancqu Member

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    Or a little less of sodium bisulfate. Sulfuric acid; often
    replaceable with a bisulfate. Dan