Re: Oxalic Acid Presoak for some pt/pd papers?
Paul's suggestions are all on the mark. I would like to add a footnote
to item #3:
You may need concentrations of oxalic of 5 or even in some cases 8-10%
to get rid of the buffering agents in Fabriano. This paper's buffering
can be highly variable. I am still printing from a batch I bought
about three years ago, and a 5 minute soak at 2% works fine. Some of
the more recent batches I have used in workshops have needed 7.5% for
15 minutes! In short, YMMV. It is a great paper, as long as the
buffering has been neutralized. The trick is in finding out exactly
how much acid and time is needed for the batch you happen to have.
On Mar 27, 2009, at 6:34 PM, Paul Viapiano wrote:
Dan, I'm sure others will chime in but my findings are:
1. Fabriano EW, Arches Cover, Rives BFK, Stonehenge
2. Helps with better dMax, and general tonality, etc...so much of
today's papers are so alkaline, heavily buffered, etc that the
acidic pt/pd solution hits the alkaline paper and poor results occur.
3. 1 - 1.5% oxalic acid in water for 3-5 minutes...Stan Klimek also
recommends this in the Arentz addendum. I dry flat on paper towels,
but hanging is ok. I just don't want my corners marked with clips.
4. The Arentz book hasa whole chapter on paper; which ones are good
to go as is, which need acidification, etc...
Fabriano EW is my choice with excellent results. Platine is a great
paper, but I've never produced the same or as good results as the
After acidification, the single biggest tip is to humidify the
dried, coated paper pre-exposure, and after you put the neg/paper
sandwich in the frame, cover it with a piece of mylar the size of
the frame before you put the back on and lock it up. Keeps the
humidity in the paper during exposure and wow...! That made all the
difference in my printing (also from Stan Klimek)...
Hope this helps...
----- Original Message ----- From: "Dan Burkholder" <email@example.com>
Sent: Friday, March 27, 2009 4:07 PM
Subject: Oxalic Acid Presoak for some pt/pd papers?
Sorry if this has been beaten to death on the list already but a
Spanish friend wants the particulars of using a weak Oxalic acid
presoak for some of his pt/pd printing. He's running into some
monster- long exposure times as he prints on hand-coated inkjet
papers. He has his reasons for doing this. Frankly, I'm impressed
he's getting the results he is using a paper that isn't formulated
for any kind of wet process. He hasn't checked the pH of the paper
and that seems like a good place to start. In the mean time...
Here are some questions to stir discussion:
1. What papers are noted to benefit from the acid presoak?
2. What problems (lower D-max, mottling, etc.) does the presoak
3. What are the recommended acid dilutions and times and drying
procedures for this procedure?
4. And anything else that you think would help.
I've never done the presoak thing but I am curious as to what
others have to say about it.
Thanks in advance for any help and suggestions.