[alt-photo] Re: dilution of pt/pd - water in the brush

[Paul Viapiano]

Here's something I'd like to know...when you buy FO solution from B&S, is it 
straight FO or do they add oxalic acid to it?

Same question with their dry pack...? Just plain FO powder?

I'm imagining the answer is yes...plain, no additives.

p



----- Original Message ----- 
From: "EJ Photo" <ejnphoto at sbcglobal.net>
To: "'The alternative photographic processes mailing list'" 
<alt-photo-process-list at lists.altphotolist.org>
Sent: Friday, July 23, 2010 8:31 AM
Subject: [alt-photo] Re: dilution of pt/pd - water in the brush


> Loris,
>
> While the figures you are quoting are for nearly .5 molar solutions, I 
> make
> mine to a nearly .7M solution. Make my own ferric to liquid at a stronger
> solution than 28% +/- to a solution of approx 35%. Independent test 
> confirm
> faster and better blacks with my mixtures than those from B&S.
>
> In Ware's paper from the late 80's or early 90's, he using a .7M target 
> for
> metals and 1.4M for AFO.
>
> I'd like to point out another source of dilution and that is water in the
> brush or coating device. It all adds up to a technique. That is the bottom
> line and I say that time and time again. You can't look at just the 
> solution
> strength without the whole process. The balance of the FO/AFO to metals is
> important and is the starting point at the coating level.
>
>
>
> Eric Neilsen
> Eric Neilsen Photography
> 4101 Commerce Street, Suite 9
> Dallas, TX 75226
>
> www.ericneilsenphotography.com
> skype me with ejprinter
> www.ericneilsenphotography.com/forum1
> Let's Talk Photography
>
> -----Original Message-----
> From: alt-photo-process-list-bounces at lists.altphotolist.org
> [mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf 
> Of
> Loris Medici
> Sent: Friday, July 23, 2010 2:13 AM
> To: 'The alternative photographic processes mailing list'
> Subject: [alt-photo] Re: dilution of pt/pd
>
> BTW, let's check it:
>
> Na2PtCl4 =  382.87g / mole, therefore:
> 200g (in 1000ml 20% solution) / 382.87g (1 mole) ~=  0.52M, which is
> slightly stronger (~ 2% in molar terms) than your 0.51M Na2PdCl4 
> solution...
>
> So, 15% Na2PdCl4 is "approx." molar equivalent to 20% Na2PtCl4 and vice
> versa.
>
> Regards,
> Loris.
>
>
> -----Original Message-----
> From: Loris Medici
> Sent: Friday, July 23, 2010 9:41 AM
> To: 'The alternative photographic processes mailing list'
> Subject: RE: [alt-photo] Re: dilution of pt/pd
>
> ...
>
>> Interesting, too, that even though my PT is referred to as a "20%" 
>> (10/50)
> it is actually only 15%.
>
> No, your Pt is indeed 20% if you're using B&S Pt Soln. #3...
>
> Now, the reason for a stronger Pt soln. could be due the fact that it has
> less covering power compared to Pd... I'd definitely opt to extend the
> solution with water (in order to facilitate coating), instead of using 
> extra
> "precious" noble metal "which - theoretically, won't have the chance of
> being reduced!"
>
> Regards,
> Loris.
>
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