Re: What is green ?

Eric J. Neilsen ()
Tue, 14 January 1997 6:04 PM

On Wed, 15 Jan 1997, Philippe Monnoyer wrote:

>
> Ok Jeff, you wrote:
>
> >GREEN IS GOOD, YELLOW IS YUCK
>
>
> >(temporarily ignoring the water)
> >Fe2(C2O4)3 is Ferric Oxalate the Sensitizer (green)
> >Fe(C2O4) is Ferrous Oxalate the Exposed Sensitizer (yellow)
>
>
> >The sensitizer reacts to light, heat, or time as follows:
>
> > 3Fe2(C2O4)3 => 6Fe(C2O4) + 3(C2O4)
>
> I think we can not say that Ferric Oxalate is really green. I would call it
> bright greenish yellow. Ferrous Oxalate is clearly yellow.
> But, Jeff, I was talking about the complex salt K3[Fe(C2O4)3] (hydrated).
> This is really like fluorescent green !!
> Look, I just check in the Handbook of Chem. and Phys.:
>
> Iron (III) Oxalate: Fe2(C2O4)3.5H2O Yellow powder
> Iron (II) Oxalate: FeC2O4.2H2O Pale Yellow Powder
> Potassium Iron(III) Oxalate: K3Fe(C2O4)3.3H2O Emerald Green powder
>
>
> I've been told that some use it instead of simple Fe2(C2O4)3.
> So, guys, any comment .... ? What colour is your ferric oxal. all. Frankly
> green or greenish yellow ? I bet you use K3Fea.strauss@worldnet.att.net (C2O4)3.3H2O ! I have some
> more litterature on it, I'll be back with it.
>

Jeff and Philippe,
When I make my ferric oxalate as per the Dick Stevens receipe in The
Difinitive Guide to Making Kallitypes it is a bright emerald green. I have
also made B&S ferric achieve this bright color by adding additional
oxalic acid and 30% hydrogren peroxide. Richard's Ferric has a tendency
to be a bit yellow/brown/green. It works great with a little help.

Eric Neilsen
laplaza.org

----------