[alt-photo] Re: Question for Platinum/Palladium printers

[Loris Medici]

Hi Etienne,

I remember to read that HCl severes some of the H bonds in the
cellulose molecule, that's no good - especially in the context of
pt/pd printing, where the image is stronger than the support.

Regards & bonne année,
Loris


On 31 Ara 2011, at 20:21, etienne garbaux <photographeur at nerdshack.com> wrote:

> Loris wrote:
>
>> Bob I don't know about the image, but I'm sure that HCl is a little
>> bir too harsh to the paper (in the long term), and should be used as a
>> last resort - if everthing else fails or is (somehow) impractical...
>> BTW, I agree with the fact HCl is the most practical clearing agent.
>
> I have heard this rumor about HCl being "too harsh" for paper over and over, but I use HCl all the time -- and for multiple things -- and have never had any problems.  I pre-wash all paper for Pt prints in significantly stronger HCl -- 3.5% -- to acidify it for the iron and to dissolve any flecks of metal left after the paper was calendered at the mill (this is necessary to prevent the dreaded spots with some papers).  (I then rinse it very well, so the pH is only the teeniest bit below 7 when I coat it.)  And, of course, each print is cleared again in HCl.  As I mentioned, I neutralize the acid and leave the print slightly alkaline at the end of the process.
>
> I have found that some papers need different sizing treatments, but (i) I cannot say that this is due to using HCl either before coating or to clear; (ii) every worker finds it necessary to adjust sizing for different papers, even if they do not use HCl; and (iii) I almost never find a paper that can't be made to work well by testing different sizings.
>
> So, in my view, if someone is breaking down their paper using HCl. they are doing something wrong (most likely, leaving acid in the paper at the end of processing).  Once again, my view appears to be supported by the many antique Pt prints I have, none of which appears to have any perceptible breakdown of the paper surface or structure.  (I do have a few hand-colored prints on which the mechanical abrasion of the coloring process raised the surface nap.)
>
> Best regards,
>
> etienne
>
>
>
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