Richard S. Sullivan (richsul@earthlink.net)
Sun, 18 Jul 1999 21:30:59 -0600
At 05:13 PM 7/18/99 -0400, you wrote:
>Lukas Werth wrote:
>> ...
>> I have an opportunity to get here in Germany for a decent price
>> chloroplatinic acid, H2PtCl6.6H20. Is it possible - and feasible - to
>> produce the platinum salt needed for prints, K2PtCl4 ...
>
Jeff Mathias replies:
>I believe that you will find that the production of K2PtCl4 will also
>involve the use of aqua regia. Hopefully you've read the previous
>discussions involving gold chloride.
Dick replies in situ:
Not true in his case. He already has the chloroplatinic acid which is post
aqua regia so that is not an issue.
>
>The two cents I would like to throw in is that while K2PtCl4 is the
>double salt of platinum that is desired, it is very easy to also get
>K2PtCl6 along with its production.
Half true. It is the avenue through which K2PtCl4 is made in the most
common synthesis process. The K2PtCl6 is reduced to K2PtCl4. It is the
incomplete reduction that leaves some of the K2PtCl6.
>This later salt is not very soluble.
True
>in water and ends up as a precipitant which may cause problems such as
>specks in the print.
Not true in my experience. This is cited in some early texts but I have
added small quantities and coated it in with the emulsion with no visible
effect. I often use reclaimed sludge from the lab that Dana is scheduled to
recycle by reducing back to metal. This is dregs of various stuff from
beakers etc. It's loaded with 'Cl6, Pt black and other secondary products.
I am careful to not suck up any goop from the bottom and it makes perfectly
good prints. I give Dana back the sludge for reclamation.
This seems to be like the urban legend that iron causes problems. Phil
Davis once coated a print with a rusty nail with no ill effects. Sam Wang
also debunked this theory as well.
>At the least it will render some of the expensive
>platinum unusable by tying it up in this insoluble sludge.
True.
>Companies
>like Engelhard go to great expense to produce a pure product.
That we do.
> And
>although I have no doubt that K2PtCl4 can be produced by others, I have
>not to this day found a cheaper, purer, easier to obtain source of
>K2PtCl4 (or PdCl2) than Engelhard.
Not true. Call B+S for a quote.
Easier? Try ordering online from Englehard with a credit card. Pay
Englehard with a check and you'll wait for it to clear although they seem
to be on-again off-again about checks at all.
While you're at it, you might also try asking Englehard to help you solve
some problems you are having with your prints. You might also ask them
what they have contributed to the alt-photo community. Frankly they could
give a damn.
>
>I don't work for them. And, I don't get any commission.
I work for B+S and do get a "commission."
Cheers.
--Dick Sullivan
This archive was generated by hypermail 2.0b3 on Thu Oct 28 1999 - 21:40:36