Have you bought Ferric Oxalate from JDPhotochem?
I've posted a problem I'm having in another thread. But I wanted to ask if anyone here has purchased Ferric from JDPhotochem. If you hvae, could you tell me what color it was and if you had any problems making a solution (27%)? The Ferric Oxalate I got from them is amber colored and I cant make a solution from it for the life of me. When added to water and Oxalic acid, a gas is emitted.
After heating and stirring at 150F for a while, the milky solution turns rust colored (and only starts to emit gas once the oxalic acid is added).
I haven't read of a situation like this anywhere, any help would be greatly appreciated. Thanks!
Make your life simple, and purchase some Ferric Oxalate that you know is reliable. Also I would contact JDPhotochem ask for a refund.
Originally Posted by guruguhan
Bostick & Sullivan sell ferric oxalate you may wish to buy it there.
Ferric oxalate goes into solution, but takes quite some time to do so - a day or so is normal. You have to shake it once in a while, or zip in in the microwave for 10 seconds or so several -well, many - times, shake, zip again. Take care it does not get too hot.
Leave the cap loose, of course, or otherwise it will blast off again as you described in your other thread - which I saw too late, sorry, and will try to answer here.
Ferric oxalate is amber coloured when it does not contain free oxalic acid, and gets greener the more oxalic acid is inside. Personally, for pl/pd prints I prefer ferric oxalate with considerable amounts of oxalic acid (the exact amount is not crucial), and some EDTA tetrasodium, because prints printed in this way clear very much easier (I seem to remember having read once that too much EDTA may cause bleeding or some similar problem, but I never experienced this myself).
For kallitypes on the other hand, you want the amber colour, for the acid - presumably also other additions - causes the silver nitrate to precipitate.
However, I once tried to get ferric oxalate here in Germany, and could not get the amber-coloured stuff into solution, try as i might, wondered what was the matter, until I noted that due to a translation mistake - easy with such comparatively unknown substances - I had got ferrous oxalate (iron III oxalate, whereas ferric oxalate is iron II oxalate). Ferric oxalate turns into ferrous when it goes bad.
So you should make sure what exactly you have got. But if it is ferrous, don't despair:
My mistake turned out to be a happy accident, as it is quite easy to make ferric from ferrous oxalate: put the stuff into water add concentrated oxalic acid (made by heating the water), then add with a dropper hydrogen peroxide. A reaction will start, shake, drop again, add some more acid if necessary, or a little more ferrous oxalate if the stuff gets unwantedly greenish, after a while you have it all in solution. Give it a rest with a loose cap, as it continues to produce gas for a day or so, but then it is ready for use. I now prefer this method from bringing powdered ferric into solution.
The - necessary - test to know all ferrous is turned into ferric: put a drop into a weak sol. of Potassium hexacyanoferride: the drop must not turn blue. This is also a good test to see whether old FO is still good, provided no EDTA is inside, which makes the test useless. But rather than pouring old FO away, with a few drops of peroxide you can bring it to full spark again.
For your potassium oxalate developer: I have got the proportions somewhere, must look for them. But something must have been wrong with your testing: adding oxalic acid must bring the PH down, and what you want is neutral or slightly acidic.
The other way around......
(iron III oxalate, whereas ferric oxalate is iron II oxalate)
Originally Posted by Jorge
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Wow, thanks a lot Lukas. That's the first bit of good news I have. Can you tell me how to make the concentrated oxalic acid to add to the Ferrous Oxalate? (Assuming I have 100g of FO-how much oxalic acid to water do I add?. How many drops of peroxide? Is it hard to see the difference in Ferrous Oxalate from Ferric Oxalate when the Ferric has little or no oxalic acid? Apart from doing the test you described, is there anything else I can do to determine if it is Ferrous or Ferric?
Once I take those steps you said, am I left with a 27% solution? If not, how would I determine the strength of the solution? After you do your test to see if all the ferrous has turned to ferric, do you then add EDTA to aid in clearing (you said you like some EDTA in your FO solution)? I'll probably leave out the EDTA for now (in the FO, I'll use it as a clearing bath). If you are left with a solution after adding the oxalic and hydrogen peroxide, is there a method to turn this into ferric oxalate powder? Do you know what the gas released is during the reaction? (I'm assuming it would be the same gas I'm noticing since I was seeing it while adding oxalic acid as well).
I've heard of your Potassium hexacyanoferride test, I think, is Potassium hexacyanoferride the same as Potassium ferricyanide?
For Kallitypes, you mentioned you want the amber color. What then would I do differently than you suggested above (use the ferrous or not add the EDTA...?)
Should I only perform these steps on a small amount (15g) of the Ferrous Oxalate so I only have enough for immediate use?
Sorry for the barrage of questions. I am enjoying this, but I can't seem to find any info on it. I've tried to find a method to turn ferrous oxelate to ferric, on google, but can't seem to find any articles.
Last edited by guruguhan; 07-14-2006 at 06:54 PM. Click to view previous post history.
...and is the hydrogen peroxide just the common type I can find at drugstores (3% solutions)? (fingers crossed)
First, let's be clear about one point: I don't know whether you got ferric or ferrous o. I have never seen amber ferric o in powder form, I only have green, and my ferrous o also has amber colour. When I want fo without oxalic acid, I make it from ferrous. I also don't know how to test the powder, but I found out that mine was ferrous when it absolutely didn't go into solution, not after days. It just rested at the bottom of the bottle, and the water turned very slightly green.
I suggest you phone back to your vendor and ask him to make sure. I see no reason why he should not be honest to you, and mistakes do happen.
No, I don't know any way to change ferrous into ferric o while leaving it in powder form. I can only do it by dissolving the ferrous o. in the way described.
Adding oxalic acid assists dissolving ferric o powder, so you can't do wrong there. To make the o acid solution more concentrated, just heat up the water, add acid, stir. You will find that as soon as the water cools down, some of the acid goes out of solution again. But you really have to do this only when you want to turn ferrous into ferric, because it is easier this way to control the amount of fluid added.
I don't have enough knowledge to work out the exact final concentration, but this is not at all critical. I start with measuring out the appropriate amount, in your case, say 25 g, add maybe 50 cc water, dissolve as much oxalic acid as possible in, say, 40 cc hot water, add mayby 10 cc to the powder in water, put in drops of peroxide until the reaction starts. I shake, when the fizzing stops I add more peroxide, then more acid, always paying attention for the colour not to turn green. I continue until all powder is dissolved, and I have a clear amber fluid. Then I test, if it gets blue, I add a little bit more acid, and a drop of peroxide, test again ...
This takes mayby 20min to half an hour or me. For consistency, I would note down the amounts used, so next time you will make an fo of about the same quality. Consistency is far more important than whether you got exactly the right percetage of the solution.
To dissolve ferric o, just make a normal solution of oxalic acid, and add the ferric o powder.
No, sorry. what I use is a 35% solution.
Originally Posted by guruguhan
I did the Potassium ferricyanide test, and I'm definitly getting a strong blue color (this is on the FO solution I made which was heated for a fairly long time and became rust colored). So the stuff mixed now is defiinitly Ferrous.
I will make another small batch of fresh solution and test it. I'm guessing its Ferrous though.
Can you suggest where I might find 35% hydrogen peroxide in a major city (apart from a chem supplier - any common places)?
Can I use 15g (as this is what I have been doing) of the powder instead of 25g but keep everything else the same? If I add a crystal (or a few crystals) of potassium ferricyanide to do the test, will it not ruin the solution? (You were saying you test and if need be add more of each, and then test again). does the blue color disappear from the tested solution as the ferrous turns to ferric? Once that has happened does nothing remain of the Potassium ferricyanide?
I can't get in touch with the owner at JDPhotochem, she is away on vacation until Mid August. I bought my chems a couple months ago but didn't open them as I was given some solutions to get started from a friend. Since I got this a while ago, I'm guessing JDPhotochem will say that it became Ferrous while I had it, and might not give a refund (but it has been in an opaque container, in a box, in the dark). I will try to sort it out when she returns, but if it doesn't work out, I'm interested in learning what to do, becuase I have 250g of the stuff.
I have made an order at B&S though.
Thanks a lot Lukas, if I knew any chemists I'd be picking their brain...