Re: sodium citrate, ammonium citrate, bleeding of borders

Chris,

Do you know whether the differences you described are indeed due to the
cations and not by the other factors?

For example, one obvious variable to suspect is pH. The solution pH may
be significantly different among the three versions you prepared. The
concentration of the "reactive" species may be different due to the pH,
due to the counterion, or both. But if these are the reasons, you should
be able to cover the whole range of spectrum by using sodium citrate,
citric acid, and sodium hydroxide (or sodium carbonate).

Before attributing the differences you observed to the different forms
of citrates, this point should be investigated.

On Sun, 23 Jul 2006 21:09:20 -0600, "Christina Z. Anderson"
<zphoto@montana.net> said:
> Well, a kiss for Bob Kiss--
> I tried the sodium citrate and presto, no bleeding of borders.
>
> However, since I ran out of Platine and my order isn't coming thru for a
> week, I had switched to Cranes Cover/Platinotype. Therefore, I wondered
> if
> the reason for no bleedoff was the paper and not the developer.
>
> I decided to be fair to am citrate and bit the bullet, mixed 'em both up
> and
> today printed side by side 12 prints, half developed in sodium citrate
> and
> half in ammonium citrate. These are all my results for anyone who cares,
> and I would LOVE if anyone chimed in with different results before I go
> and
> accept it as gospel:
>
> As I think Eric and Sam said sodium is warmer than ammonium--it has a
> yellower tone to it than ammonium which is redder. Hard to see unless
> side
> by side and you scrutinize.
>
> Sodium is a titch less contrasty, too.
>
> Ammonium is a bit faster--printing less than 1/3 stop faster, though,
> probably 1/6-1/4 stop by my eyeball calcs--in other words, on a 31 step
> tablet it wasn't a full step.
>
> NOW (ta da) about the bleeding of borders, My am citrate is always
> darkened
> with metal; since it was all I used I didn't think anything of it.
> HOWEVER,
> when I developed all these prints today in sodium citrate, the developer
> stayed clear. No bleeding of borders. And the Cranes Cover prints that
> I
> developed in ammonium citrate did bleed slightly (not like Platine) in
> the
> developer, so my conclusion is the bleeding is both paper and developer
> related, and maybe another reason in there, too. But it was enough of a
> revelation to want to stick with sodium citrate, frankly.
>
> That's it for today!
> Chris
> CZAphotography.com
>
>
>
Received on 07/23/06-09:23:20 PM Z