[Alt-photo] ferrous vs. ferric

C.Breukel at lumc.nl C.Breukel at lumc.nl
Tue Mar 22 14:47:30 UTC 2016


Let me share my approach; I rarely print pure Pt, and if I do 5-10 prints: I have made my own FerricOxalate, it's quite green, here is my recipe:
(1.25 gram FeOx + 0.1 gram OxalicAcid in 4.4 ml MQ water in 30 ml flesje, na 2 uur in broekzak dragen opgelost)..I'll translate the last part: I'll carry the small bottle (carefully sealed obviously!) in my trouser pocket, it will mix and warm and be soluted in 2 hours...;-)..

Best,

Cor

-----Original Message-----
From: Alt-photo-process-list [mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf Of Jim Patterson via Alt-photo-process-list
Sent: dinsdag 22 maart 2016 15:33
To: alt-photo-process-list at lists.altphotolist.org
Cc: Jim Patterson
Subject: Re: [Alt-photo] ferrous vs. ferric

Chris, I have ruined a batch of FO by accidentally boiling it in the microwave, so I stopped being impatient.  I mix at room temp slowly.  If you have a fridge or frozen bottle of dry FO, let it come to room temp before opening it or water condenses inside the bottle.  Cosmic rays, background natural radiation, x-rays (old TVs), heat, microwaves, uv etc will reduce FO.  You can add a few drops of your FO solution to a few drops of 1% potassium ferricyanide solution and a strong Prussian blue indicates significant ferrous.
Jim

Sent from my iPhone

> On Mar 22, 2016, at 9:16 AM, Christina Z. Anderson via Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org> wrote:
> 
> Jim,
> 
> So let me ask this: I assume the factors for making ferric change to ferrous is light, air, heat, age, humidity, all those things that increase chemical reactions (remember I’m a layman). So eliminating light, air, heat, humidity as you have done makes age the only factor and obviously it would store well beyond how much longer I expect to even live so it would be a wise idea :) Wow. 40 years!
> 
> Is there a layman’s explanation of why ferric goes to ferrous?
> 
> Is there a visible color shift that would show that the ferric changed to ferrous like there is in potassium ferricyanide to potassium ferrocyanide?
> 
> Chris
> 
>> On Mar 22, 2016, at 8:09 AM, Jim Patterson via Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org> wrote:
>> 
>> Hi Chris, ferric oxalate is slowly soluble in distilled water (takes me 2 days, in darkroom, stir it several times a day).  Ferrous oxalate is poorly soluble.  I have a bottle of dry ferric oxalate from B&S from 1970s, wrapped in aluminum foil, kept in fridge, and it still works.
>> Jim
>> 
>> Sent from my iPhone
>> 
>>> On Mar 22, 2016, at 8:55 AM, Christina Z. Anderson via Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org> wrote:
>>> 
>>> Chemistry question here:
>>> 
>>> I apologize that I did not follow the discussion of the last several months about hard-to-dissolve ferric oxalate because I always buy mine ready-mixed from Bostick following a discussion years ago about this very issue. I’ve never used it dry. Their solution lasts a couple years and if I buy a large quantity I store it in the fridge and it has never gone bad on me.
>>> 
>>> I am wondering though whether buying it in the powder form is a) a good idea and b) has a longer shelf life?
>>> 
>>> Am I correct in assuming ferric can change to ferrous with age?
>>> 
>>> And that ferrous is harder to dissolve than ferric?
>>> 
>>> And that if your “ferric oxalate” powder is hard to dissolve/never dissolves that means it  has changed to the ferrous form?
>>> 
>>> I guess I am just trying to ascertain whether there is any benefit to buying and storing the powder and how long the shelf life is. I assume people mostly do this for the cost savings if they are uber-platinum printers doing it on a daily basis (like I buy gum by the gallon).
>>> 
>>> Chris
>>> 
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