RE: Pt./Pd. question acid pre-soak

If your ferric is only going to be used for platinum/palladium printing, I
believe you are more able to play with it. I would even say that PT and PD
solutions may react to different amounts of oxalic acid. It might also be
interesting to see if the additional of different EDTA di vs tetra has any
impact as di is pH 7ish and tetra is around 10ish if memory serves me
correctly. I did add some edta to some early batches of home brewed ferric
and produced a nearly insoluble solid; at least it was solid in water once I
was able to get it out of the bottle.

Has any one tried precoating with Ferric Nitrate solution?

Eric Neilsen Photography
4101 Commerce Street
Suite 9
Dallas, TX 75226
http://e.neilsen.home.att.net
http://ericneilsenphotography.com
 

> -----Original Message-----
> From: Sandy King [mailto:sanking@clemson.edu]
> Sent: Thursday, August 11, 2005 5:23 PM
> To: alt-photo-process-l@sask.usask.ca
> Subject: RE: Pt./Pd. question acid pre-soak
>
> Eric,
>
>
> Exactly. I was trying to figure out if anyone had done any tests
> matching the acid in the developer to the acid of the pre-soak.
>
> Some of the papers I use don't like the pre-soak, Stonhenge being one
> of them, The acid pre-soak simply removes the coating of this paper
> so when you print with it it absorbs a huge amount of sensitizer, and
> the resulting prints have very granular look.
>
> Sandy
>
>
>
>
>
>
> >Sandy, that makes more sense. So the testing that was done with the 1%
> to
> >2% oxalic acid treatment was to soak it in a bath or was it coated on and
> >let dry? (I coated on a 2% solution for my test.)If I were looking to
> >counter act a reaction, I'd look to an equivalent. So if for instance I
> was
> >coating a 16x20 piece of paper with a 2% solution, I could quantify the
> >amount of oxalic acid in total grams used. This would be quite difficult
> if
> >I soaked it and is still questionable as described. I could then add the
> >same amount to my coating solution and see what happened. This assumes
> an
> >awful lot, in that the oxalic acid added to solution would not be used or
> >restricted by the coating solution.
> >
> >The reason I revised your question ( made it my own) was that I see it
> >either as an oxalic acid issue somehow acting on the ferric to ferrous
> >equation or it is a pH issue and a lower pH somehow allows for a more
> >complete reaction between the metal salts and the ferrous ions generated
> by
> >the addition of UV light to the coated paper. Leaning strongly toward the
> >former, I made suggestions towards that end. I can see however, from
> your
> >further clarification, that you appear to be matching the acid to the
> >developer to see if it somehow compliments that reaction.
> >
> >
> >
> >
> >Eric Neilsen Photography
> >4101 Commerce Street
> >Suite 9
> >Dallas, TX 75226
> >http://e.neilsen.home.att.net
> >http://ericneilsenphotography.com
> >
> >
> >> -----Original Message-----
> >> From: Sandy King [mailto:sanking@clemson.edu]
> >> Sent: Thursday, August 11, 2005 2:09 PM
> >> To: alt-photo-process-l@sask.usask.ca
> >> Subject: RE: Pt./Pd. question acid pre-soak
> >>
> >> Eric,
> >>
> >> You are absolutely right. My ferric oxalate solution has a pH below
> 2.0.
> >>
> >> I made a big mistake in relating what I did. What I meant to say was
> >> that I added oxalic acid to the potassium oxalate developer in
> >> amounts to get it into the pH 5.8 range.
> >>
> >> I have always added oxalic acid in excess up to about 5% to my ferric
> >> oxalate solutions. In other words, I mix the basic ferric oxalate
> >> solution form powder (I am currently using the Artcraft version), and
> >> after mixture add about 5% oxalic acid on a weight to volume basis. I
> >> did test the addition of oxalic acid over a fairly wide range, from
> >> slightly in excess up to about 10% in excess, but all that really
> >> seems to matter is that it be slightly in excess. Certainly more than
> >> 5% is pointless. I did not, however, test the pH of the ferric
> >> oxalate during those tests.
> >>
> >> I apologize for the confusing comment.
> >>
> >> Sandy
> >>
> >>
> >>
> >> >Sandy,
> >> >Your ferric oxalate has a standard pH of 6.5? I shall need to go back
> >> into
> >> >my data sheets for confirmation on this but I believe that mine is
> down
> >> in
> >> >the 2 range. Did you start with B&S powder or a Formulary liquid?
> Other?
> >> >
> >> >Eric Neilsen Photography
> >> >4101 Commerce Street
> >> >Suite 9
> >> >Dallas, TX 75226
> >> >http://e.neilsen.home.att.net
> >> >http://ericneilsenphotography.com
> >> >
> >> >
> >> >> -----Original Message-----
> >> >> From: Sandy King [mailto:sanking@clemson.edu]
> >> >> Sent: Thursday, August 11, 2005 12:19 PM
> >> >> To: alt-photo-process-l@sask.usask.ca
> >> >> Subject: RE: Pt./Pd. question acid pre-soak
> >> >>
> >> >> Eric,
> >> >>
> >> >> I ran the same tests, i.e. adding extra oxalic acid to the ferric
> >> >> oxalate. I don't remember exactly how much I added but I did test
> >> >> the pH with varying amounts added, and although the pH of oxalate
> >> >> solution changed from 6.5 down to below 5.8 I did not observe any
> >> >> increase in Dmax.
> >> >>
> >> >> Sandy
> >> >>
> >> >>
> >> >>
> >> >>
> > > >>
> >> >>
> >> >> >Kerik, How much "extra" oxalic acid did you try adding to the
> ferric
> >> when
> >> >> >you ran those test? And were you able to check the pH of the
> solution
> >> >> after
> >> >> >adding it?
> >> >> >
> >> >> >Eric Neilsen Photography
> >> >> >4101 Commerce Street
> >> >> >Suite 9
> >> >> >Dallas, TX 75226
> >> >> >http://e.neilsen.home.att.net
> >> >> >http://ericneilsenphotography.com
> >> >> >
> >> >> >> -----Original Message-----
> >> >> >> From: Kerik [mailto:kerik@kerik.com]
> >> >> >> Sent: Tuesday, August 09, 2005 11:17 AM
> >> >> >> To: alt-photo-process-l@sask.usask.ca
> >> >> >> Subject: Re: Pt./Pd. question acid pre-soak
> >> >> >>
> >> >> >> With certain (apparently) highly buffered papers like Fabriano
> >> >> Artistico
> >> >> >> Extra White, it is absolutely true. And just adding oxalic to
> the
> >> >> ferric
> >> >> >> didn't have the same effect. Other papers that aren't as
> buffered
> >> will
> >> >> >> show little or no change after being soaked in oxalic acid.
> >> >> >>
> >> >> >> Kerik
> >> >> >>
> >> >> >>
> >> >> >> >> I ran test when this was talked about years ago and found
> >> little to
> >> >> >> >> support it. I did not run test on a large sample of papers.
> I
> >> also
> >> >> >> >> queried those that made the claim to see if they could also
> >> just
> >> >> add
> >> >> >> >> some oxalic acid to their ferric and achieve the same
> increase
> >> in
> >> >> dmax.
> >> >> >> >> I got no response.
> >> >> >> >>
> >> >> >> >> Or is it simply a pH issue? Years ago Martin Axxon had
> >> suggested to
> >> >> me
> >> >> >> >> that he felt a lower pH paper gave a better print with PT
> >> solution.
Received on Thu Aug 11 17:21:41 2005