[alt-photo] Re: dilution of pt/pd
Terry King
terryaking at aol.com
Sat Jul 24 09:49:10 GMT 2010
It is not about acquisition of knowledge but about whether that knowledge is relevant to the objective.
If using kits is better for you fine, but in my circumstances, the method I use is easier and cheaper.
Why do you need special instructions for dissolving the platinum and palladium salts when you can just add distilled water in much the same way as you dilute the ferric oxalate but with the precious metal solutions you just need to give them a shake. I would also suggest that one can make fine platinum prints without all the maths in Dick Arentz's book.
I had one student who bought some pure ferric oxalate from B & S, good stuff, nothing wrong with it, but it did not produce good platinum prints in the same way as the ferric oxalate as we had made in class without using molar solutions. The problem was solved by adding oxalic acid to the B & S solutions. unsurprisingly,we deduced that the ph of the dilution had to be more acid. From other experience we also deduced that he it needed to be an organic acid. Why should that be ?
The results of our tests show that it makes no difference whether you use ammonium ferric oxalate or ferric oxalate in making platinum prints. These and other circumstances have led myself and others, including those with great chemical expertise, to doubt Dr Ware's chemistry even if that is lese majesty.
Just as a tip, don't try weighing gold salts in humid conditions as the weight will increase as the salts absorb water from the atmosphere.
In the right circumstances using molar solutions clearly makes sense. But should you drag them into making a platinum print from stock materials when making the picture is the objective?
Over-complication and trying to reinvent the wheel has led many to leave this list. Remember the discussion about the size of the holes in garden misters?
If you are going down the A3 from London to Portsmouth call in at Ockham, just north of Guilford, and , at the parish church,pay homage to William of Ockham, who, in the 13th century propounded the principle of excluding from an argument those elements which are unnecessary. This is Ockham's razor.
Keep it simple.
Terry
-----Original Message-----
From: ender100 at aol.com
To: alt-photo-process-list at lists.altphotolist.org
Sent: Sat, 24 Jul 2010 5:16
Subject: [alt-photo] Re: dilution of pt/pd
I often buy kits from B&S for a few of reasons.
1. The chemistry is very consistent.
2. FO from other sources has sometimes been a problem in that it won't
dissolve.
3. B&S usually offers the "student kit" that includes the FO free.
4. It is easy for students in my workshops to go home and order the same
chemistry and get consistent results.
5. I order developers and FO in dry packs to save on shipping and to extend the
shelf life of the FO—I date the FO when I mix it with distilled water.
6. A handy thing about the B&S FO in the 25 ml dry packs is that you can top
off the bottle to the top of the label and you have exactly 25 ml of solution.
Very easy to do.
I do have Palladium powder to mix my own Palladium as per the instructions in
Dick Arentz's book.
I am sure there are other suppliers for chemistry that are very good and very
reliable.
I would be interested (like David) in hearing comments about adding oxalic acid
to FO and the purpose for doing so—to make it dissolve easier? Does the FO from
B&S have oxalic acid added to it?
Sources for small electronic scales both used and new are those companies that
supply the ammunition reloading folks. RCBS and others make very fine scales. I
have an RCBS—works both for my reloading and for my photo chemistry. I think it
measures to .01 gram.
I do think the discussion about molar solutions has been quite interesting and
rings a bell with my high school and university chemistry classes. Thanks to
Loris, Eric and Paul for their time lending their knowledge. If people prefer
to use % solutions fine, if others prefer to use molar solutions, fine. I
wouldn't consider either to be "pointy hat." There is nothing dangerous about
acquiring knowledge and a better understanding of the universe if you wish to do
so. We don't burn witches at the stake any more, do we?
Mark Nelson
www.PrecisionDigitalNegatives.com
www.MarkINelsonPhoto.com
PDNPrint Forum @ Yahoo Groups
-----Original Message-----
From: David Ashcraft <davidashcraft at sti.net>
To: The alternative photographic processes mailing list <alt-photo-process-list at lists.altphotolist.org>
Sent: Fri, Jul 23, 2010 9:38 pm
Subject: [alt-photo] Re: dilution of pt/pd
> Who is using kits ? Why not get the salts straight from chemical > suppliers ?
I am using premixed from B&S! When I looked for the chems to make from scratch
what I was able to find didn't impress me in savings and when I factored the
time it would take to measure and mix I figured it wasn't worth it. Perhaps the
suppliers were the wrong ones but the s&h and time just didn't make sense to me.
Although, the fact that I could try different formulas does intrigue me. Which
brings me to a question. Could you add to an already mixed solution of FO some
Oxalic acid? Of course as long as the proportions are respected. I ask because
of the formulas I have found have the FO listed as the last ingredient and to my
understanding you mix ingredients in the order listed.
David
On Jul 23, 2010, at 4:25 PM, Terry King wrote:
> Well the discussion would certainly seem to confirm that all this > chat
about molarity is very pointy hat.
>
>
> There are other strange happenings.
>
>
> Who is using gramme scales to measure noble metal salts, or can you > measure
tenths on them? Accurate scales measuring down to a tenth of > a gramme and less
are not expensive and are easily available.
>
>
> Who is using kits ? Why not get the salts straight from chemical > suppliers ?
>
>
> Who is using molar calculations with cyanotypes, the cheapest and > simplest
of processes ?
>
>
>
>
>
>
>
>
> 'Molarity' has it's place but somebody is going to have to > demonstrate that
you can get a better print for less money with less > effort to justify a
departure from good old percentage calculations.
>
>
> Making good alternative process prints is simple in terms of the > process if
making pictures is your objective. You need practice and > judgement and an eye
for a good picture to make really good ones. > All this pointy hat stuff just
gets in the way.
>
>
> Terry
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: Loris Medici <mail at loris.medici.name>
> To: 'The alternative photographic processes mailing list' <alt-photo-process-list at lists.altphotolist.org>
>
> Sent: Fri, 23 Jul 2010 13:35
> Subject: [alt-photo] Re: dilution of pt/pd
>
>
> Clay,
>
> -----Original Message-----
> From: alt-photo-process-list-bounces at lists.altphotolist.org On > Behalf Of
> Clay Harmon Website
> Sent: Friday, July 23, 2010 3:08 PM
> To: The alternative photographic processes mailing list
> Subject: [alt-photo] Re: dilution of pt/pd
>
>> This thread has been entertaining in a strange, twisted way.
>
> Agree. :)
>
>
>> Let me see if I have this right:
>>
>> 1. The traditional formulas for pt/pd printing are based on >> percentages
> and are not quite chemically balanced. In fact, there is a modest > amount of
> waste of the
>> pt/pd metal salt because of this imbalance.
>
> I've corrected this in a recent message.
>
>
>> 2. It does not really make much difference in terms of print quality,
> because there is an overabundance of metal relative to ferric > oxalate with
> the traditional formula.
>> It works fine, in other words.
>
> Well, I have to see prints to say something about that! ;) Having > balanced
> formulae doesn't guarantee fine prints, right?
>
>
>> 3. If you don't want to needlessly flush noble metal salts down the >> drain,
> make a one-time adjustment to your formulation and keep printing.
>
> Yep. :)
>
>
>> 4. If you don't care and don't want to think about it, and believe a
> modest amount of waste in printing lends a sassy and insouciant 19th > century
> flair to your
>> printing practice, just keep doing things the way you always have.
>
> That was good! :) Each to their own, for sure...
>
>
>> Did I get this right?
>
> Kinda... I thought the actual debate was on the issue of whether > talking
> about stoichiometry and/or molarity in a public alt-process forum is > an
> unnecessary "pointy-hat" behaviour and to "over-complicate" things, > or not.
> Which later evolved to whether the concept of molarity does have a > use for
> us simple / helpless / poor mortals, or not... But you can't be sure > with
> Terry! :)
>
>
> Regards,
> Loris.
>
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