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johnielvis
23-Aug-2011, 04:55
(REVERSAL BLEACH).

ANYWAYS--for the chemists---can you substitute acetic acid or any other over the counter type acid for sulphuric acid when making dichromate reversal bleach solution.

it was my understanding that the dichromate in an acid solution will do the job, but they only seemed to use sulphuric or sulphamic acid for some formulas.

I'd like to be able to use acetic if possible--clean,easy to get still compared to sulphuric around these parts.

SO--anybody KNOW what will work or what should be avoided....i do not want any nasty troubles or to get evicted...Any chemical types out there that can explain the theory so that I can determine such things myself maybe????? I'd like to know they whys as well as the the what's if possible....thanks.....

yes I've researched and have determined that it may likely work...but I don't want any nasty reactions...I'm willing to waste time experimenting, but not my eyesight or health, you know.

Robert Hughes
23-Aug-2011, 06:25
I don't think you can substitute for sulphuric acid. I tried using acetic acid a couple years ago, nothing happened.

Best bet for sulphuric acid: get an old car battery and take it to the battery shop for a refill. They won't sell sulphuric without a battery to pour it into. I guess terrorists don't have access to old batteries, so you're in the clear.

johnielvis
23-Aug-2011, 08:14
BLAST......well, I know that hydrochloric makes it intensifier....so there's some funny stuff going on other than something having the right PH

too bad about the acetic...was it the strong stuff str8 from the bottle or diluted?

I got no glacial but I do got some stop bath laying around.....maybe you didn't wait long enough?....did absolutely NOTHNG? ...not even boil like the horror flicks? at least I'm hoping it didn't cause any sort of objectional/toxic releases.....

anyways--any other war stories...hopefully SUCCESSFUL substitutions????

D. Bryant
23-Aug-2011, 08:17
(REVERSAL BLEACH).

ANYWAYS--for the chemists---can you substitute acetic acid or any other over the counter type acid for sulphuric acid when making dichromate reversal bleach solution.

it was my understanding that the dichromate in an acid solution will do the job, but they only seemed to use sulphuric or sulphamic acid for some formulas.

I'd like to be able to use acetic if possible--clean,easy to get still compared to sulphuric around these parts.

SO--anybody KNOW what will work or what should be avoided....i do not want any nasty troubles or to get evicted...Any chemical types out there that can explain the theory so that I can determine such things myself maybe????? I'd like to know they whys as well as the the what's if possible....thanks.....

yes I've researched and have determined that it may likely work...but I don't want any nasty reactions...I'm willing to waste time experimenting, but not my eyesight or health, you know.

1) Acid stop contains no dichromate.
2) Acetic acid is an organic acid, sulphuric - inorganic, an neither can be substituted for the other.
3)Sulphamic and sulphuric cannot be used to substitute for the other,
4) For a reversal bleach typically calls for sulphuric acid.
5) Be extremely careful with concentrated sulfuric acid it can do a lot of nasty things.

Nathan Potter
23-Aug-2011, 08:45
What are you bleaching? Sounds like color reversal film; maybe Ilfochrome? B&W film can be bleached with any of a number of silver solvents - the objective of any bleaching process being to remove silver previously precipitated by a developer. Acetic acid is not a silver solvent so should not be effective under any but extraordinary circumstances of bath chemistry.

Color bleaching depends greatly on the chemistry in the emulsion since the bleach must reduce silver with attached color couplers or in some systems the couplers alone or the silver alone. One needs to distinguish between chromogenic and non-chromogenic systems where the dye is formed in the emulsion or originally deposited in the emulsion.

If you are working with Ilfochrome (Sulfamic acid bleach) you will not be successful using an acetic acid replacement. I believe it has been very difficult to find an adequate replacement for sulfamic acid as indicated by a number of workers attempting to fabricate their own chemistry. Can't help you with this application unfortunately.

Nate Potter, Austin TX.

johnielvis
23-Aug-2011, 08:53
it's black and white--I got a bunch of sodium dichromate and I'm at the last quart of my kodak dichromate bleach concentrate, so I'll have to start mixing my own....

I don't want to have to go through hassles getting acids that work like sulphuric is a pain these days to buy.....I can get acetic pretty easily at helix or calumet...but, yes, apparently that will not work.

Ihave hydrochloric--that I can get, but it turns dichromate into intensifier!!!

someone said that soidum bisulFATE would work---anybody know what the proportions should be? I'd like to use the dichromate I got, so what else do I need bESIDES sulphuric?

Nathan Potter
23-Aug-2011, 14:52
OK. The more normal bleach formula uses Potassium bichromate with say 10ml Sulfuric acid conc. per liter of water. Some people substitute Potassium permanganate for the bichromate since the chromate is most likely a carcinogen but you're still stuck with the weak H2SO4 solution. But that solution is weak enough so It'll act as a fingernail cleaner if you dip quickly.

There are a number of silver reducers that could be tried and Potassium ferricyanide is most common. Also just Farmers reducer but I've never messed with these as a bleach for a reversal process - there could be some incompatibilities. It would be key to keep the complexed silver locked up in solution through the second development process.

Nate Potter, Austin TX.

Erik Larsen
23-Aug-2011, 15:45
Last month I walked into my local Auto Zone and bought a liter of battery acid. The clerks didn't think twice about selling it to me. I think it 6 or 8 bucks. Maybe the laws are different in your neck of the woods?
It's worth asking.
Regards
Erik

johnielvis
23-Aug-2011, 16:14
yeah....can't get battery acid with resorting to BS...so..I know I can get the sodium hydrogen sulfate from the pool store...NOW....the formula from anchell's book is

postasium dichromate, 6.0 g
water to make 1.0 litres
12.0 ml sulphuric acid concentrate.....

now I candirectly substitute the sodium dichromate...BUT...what about how much of the sodium bisulfate would it take to get the same "acid" as 12.0 ml sulphuric acid concentrate....how strong IS sulphuric acid concentrate? I"ve seen percentage solutions...but what is standard concentrate? from that we can get how much of the other stuff it will take if we assume that it is half neutralized sulphuric acid in solution...

Robert Hughes
24-Aug-2011, 08:59
Maybe the laws are different in your neck of the woods?

Minnesota State Law has decided that sulphuric acid is too dangerous to allow in public - except for all those millions of car batteries, of course.