Ferric Oxalate

[Andrew O'Neill]

I'm hoping that Sandy King or someone else with lots of experience with kallitypes will respond. I am mixing up some FO for the first time in distilled water at about 52 C. It's sitting on a hot plate.
Man, they weren't kidding when they said it takes a long time to go into solution.
When I mixed in the FO it looks creamy coloured. I'm mixing mixing mixing...getting pretty sick of mixing. It's still hasn't mixed in. When it is finally in solution, is it clear? What does it look like?

[Don Hutton]

There's a very extensive thread on Apug about dissolving ferric oxalate and some problems with a recent batch. When it's working, it dissolves fairly quickly into an opaque solution which looks like pea soup - then as it cools over about 45 minutes, it clears. I personally use water at about 140+F.

[D. Bryant]

I'm hoping that Sandy King or someone else with lots of experience with kallitypes will respond. I am mixing up some FO for the first time in distilled water at about 52 C. It's sitting on a hot plate.
Man, they weren't kidding when they said it takes a long time to go into solution.
When I mixed in the FO it looks creamy coloured. I'm mixing mixing mixing...getting pretty sick of mixing. It's still hasn't mixed in. When it is finally in solution, is it clear? What does it look like?
Andrew,

See my reply to your question on APUG.

Don Bryant

[neil poulsen]

I had some Ferric Oxalate I purchased from Photographers' Forumlary that didn't work for me. Trying to get it dissolved into distilled water was terrible. (It came in green, chunky crystals.) I got some from Bostick and Sullivan, and getting it dissolved was much better. So were the printing results. It comes in a very fine green powder.

I too am just getting started. Bostick and Sullivan offered the following advice, and it worked.

>> Double the amount of EDTA from 6gms per 100ml solution to 12gr. to aid dissolving.

>> In dissolving, heat the solution as high as 175degF, but not much higher. (The Ferric Oxalate can break down at higher temperatures that approach the boiling point.)

>> Put in the Ferric Oxalate a little at a time during mixing and heating, if you're having trouble. (Although, Keven at Bostick and Sullivan said that he's fairly cavalier about mixing in the powder with the heated distilled water, and he doesn't have a problem.)

>> I noticed at these higher temperatures, or even at 145degF, that the water evaporates away while mixing. As opposed to adding water after evaporation to maintain proper levels of water, my logic was to add the extra water prior to evaporation, and then let it evaporate down. This makes it easier to dissolve the Ferric Oxalate into solution, because there's more distilled water initially. (Kevin thought this was a good idea.)

>> Depending on the graininess of the particular Ferric Oxalate that you have, consider getting a morter and pestle to grind it down further.

>> A long time ago, I got a magnetic stirrer that's built into a hot plate. With Ferric Oxalate, I would argue that this is more of a necessity than a luxury. It sure works great. I use a small stirrer in a 30ml or 50ml beaker to mix smaller quantities of Ferric Oxalate.

>> If there're still a few particles that haven't dissolved after extensive stirring, consider filtering them out. But my limited experience is that, with good chemistry and mixing, this shouldn't be needed.

The final solution should be a nice, clear, olive brown solution.

[phil sweeney]

I always mix mine with 120 degree F distilled water. I usually stay with the solution on/off about 15 minutes continually mixing. Then every 1/2 hour for a couple hours I'll give it a good mix. Later in the day I place the solution in my eyedropper bottle (still not clear but no sediment). It will finally be clear the next day. Always mix 24 hours in advance. I have never had problems. Have fun.