iodine for bleaching

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i need to bleach some prints and don't have my ferricyanide with me.

i vaguely remember reading somewhere that its possible to bleach prints using iodine?

if true, what is the process?

thanks

-- James Luckett (jl@mollymail.com), September 25, 2001

Answers

I did a quick search on the internet, and gather that most iodine bleaches are quite strong and are used for bleaching to a total white. One was a two-part formula using iodine and potassium iodide in one solution and highly toxic potassium cyanide in the other. I did find a formula in one of the forums that seems to be part A of the previous formula: .4% iodine and 1.5% potassium iodine. I couldn't find one with just straight iodine. I have also heard of a formula that simply requires adding 10 or 15 grams of citric acid to ordinary rapid fix, but when I tried it it didn't work.

-- Ed Buffaloe (edb@unblinkingeye.com), September 26, 2001.

Sol1:

Potassium iodide 15g Iodine 5g(stock) Water 100ml

Sol2 Sodium thiosulphate 200g in water for 1 litre

Dilute sol1 in the proportions: 1 part + 5 parts water Use as ... potassium ferricyanide fix in sol 2.

Source: The photographers Master printing course; Tim Rudman

-- Marc Leest (mmm@n2photography.com), September 26, 2001.


I'm keen to try this bleach formula. It seems iodine crystals are a bit pricey from Photographers Formulary, but I learned that they are also used to fume fingerprints, and there is a company that sells them relatively cheaply ($30 for 100 grams) at http://www.redwop.com/products.asp?pID=1699. Apparently iodine crystals have a tendency to go straight from a solid to a gas. Does anyone know if this tendency can be reduced by refrigerating them? Also, are there any advantages of iodine bleach over ferricyanide bleach?

-- Ed Buffaloe (edb@unblinkingeye.com), September 28, 2001.

I know that iodine based bleach can be used if you want to avoid the brown color that sometimes occurs when using Farmer's Reducer on prints. I'm not sure about how to store the stuff, though.

-- Steve Wiley (wiley@accesshub.net), October 02, 2001.

this sounds a little more complicated than i was imagining. i mostly wanted to avoid buying another giant bottle of potassium ferricyanide from the local photo store for $16. i was hoping i could just walk over to the walgreens and spend a few bucks on some iodine and dilute it.

-- James Luckett (jl@mollymail.com), October 02, 2001.


The note about it not changing print color fascinates me. I assumed the change in color comes because of the reduction in grain size caused by the bleach, but perhaps there is a chemical reaction as well. I'd love to be able to selectively reduce a warm-tone print and not have the reduced areas change color when toned in selenium.

-- Ed Buffaloe (edb@unblinkingeye.com), October 02, 2001.

i vaguely remember that when i read about using iodine as a bleach, it said to just get a bottle from the drug store and dilute it. so thats what i tried out. got "iodine tincture" - iodine 2 percent, sodium iodide 2.4 percent, and alcohol 47 percent.

straight from the bottle it zaps any part of your print to paper base white almost instantly.

diluted the 1 oz bottle with about 30 oz of water. bleach action worked slowly but and much less harshly than ferricyanide. and no color change. nothing seemed to happen when i refixed the prints. but putting the fixed prints back in the iodine mixture seems to slow down the process considerably.

then toned prints in selenium. i usually go for a slight split tone look. prints in iodine didn't split, just and overall chocolote color. un-iodined prints toned better - got that split i like.

hope this makes sense to someone.

-- James Luckett (jl@mollymail.com), October 11, 2001.


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