Re: Another Ziatype question

Dick Arentz' formula for the ferric oxalate solution A calls for the
addition of about 1.5% by weight of oxalic acid.

Jeffrey Mathias also tested the addition of oxalic acid in amounts
ranging from 1-10% and suggests that benefits may be seen in amounts
from 2-5%. I don't recall that he mentions any improvement in Dmax
but when I tested this I found a slight increase, about log 0.07, in
Dmax using both Stonhenge and Lennox papers.

As for the oxalic acid soak, I have had problems with several papers,
including Stonhenge, using the soak. The soak appears to break down
and remove the surface sizing, the result being a more granular or
textured look. On another forum Clay mentioned that the papers that
benefit most from an oxalic acid soak are those that are heavily
sized, "floaters" as he calls them.

Note: my comments are about DOP Pt./Pd and may not apply to ziatype.

Sandy

>Ok, things become clear now... Thank you very much for reminding
>Clay's article!
>
>What do you think about including a trace amnt. of 1% oxalic acid
>into sensitizer? (for instance: 1 drop = 0.05ml to 1ml sensitizer)
>
>It seems that PH of paper and/or developer/washing water is very
>important in Pt/Pd printing... It seems that I have to seriously
>study this issue.
>
>Thanks,
>Loris.
>
>----- Original Message ----- From: "Don Bryant" <dstevenbryant@mindspring.com>
>To: <alt-photo-process-l@sask.usask.ca>
>Sent: Tuesday, October 12, 2004 12:28 AM
>Subject: RE: Another Ziatype question
>
>
>Loris and Christian,
>
>Although I've never used Whatman HP, Clay Harmon writes in his article about
>Gum over Platinum, that Whatman HP should be treated to a 1.5% oxalic soak
>to prepare for palladium printing. I assume that may hold true for ziatype
>printing as well with that paper.
>
>Don Bryant
Received on Mon Oct 11 18:39:47 2004