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  1. #1

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    New bleach bath (non-toxic)?

    Wandering on the net I've stumbled across the following site [COLOR=DarkRed]http://www.a1.nl/phomepag/markerink/hieslide.htm[/COLOR].
    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. #2

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    Quote Originally Posted by Alessandro Serrao
    Wandering on the net I've stumbled across the following site [COLOR=DarkRed]http://www.a1.nl/phomepag/markerink/hieslide.htm[/COLOR].
    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?
    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. #3

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    Quote Originally Posted by Jorge
    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.
    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. #4
    Ole
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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.
    -- Ole Tjugen, Luddite Elitist
    Norway

  5. #5

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    Quote Originally Posted by Alessandro Serrao
    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.
    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. #6
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    Anyway, who said copper sulphate is non-toxic? I don't want any in my mouth.
    Gadget Gainer

  7. #7

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

  8. #8

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    Quote Originally Posted by Alessandro Serrao View Post
    Wandering on the net I've stumbled across the following site [COLOR=DarkRed]http://www.a1.nl/phomepag/markerink/hieslide.htm[/COLOR].
    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?

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

  9. #9
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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. #10

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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?

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