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 address?
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.