Don wrote:
>> FWIW, one fellow on APUG reports that he is successfully using a weak
>> solution of hydrochloric acid as a substitute for oxalic acid to presoak
>> paper for palladium printing.
Ryuji replied:
> If this is true, the acid mechanism is more likely than the iron
> mechanism. That means any reasonable acid that dissolves and neutralizes
> calcium carbonate and does not interfare with the process being used
> would be usable for the presoak step.
I'm sorry, I didn't realize this question was on the table. I have used 2%
hydrochloric, 2% sulfuric, 3% phosphoric, 5% formic, and 5% citric acid for
neutralizing alkaline papers prior to coating the iron processes (I do Pt
[no Pd], kalli, and cyano). I rinse thoroughly after the acid bath (final
rinse in distilled water), and have not noticed any difference between
them. As far as changes in contrast or scale, I wouldn't say the acid
changes these parameters -- I'd say that alkaline paper screws up iron
processes, and must be neutralized before coating to get the "base" results
for that paper. It's the results on un-neutralized paper that are
anomalous.
Best regards,
etienne
Received on Mon Aug 15 13:59:51 2005
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