From: Judy Seigel (jseigel@panix.com)
Date: 12/05/02-02:46:14 AM Z
On Thu, 5 Dec 2002, Liam Lawless wrote:
> P.S. The scale was several steps shorter with the unbuffered paper (equals
> a more contrasty print), though whether this is actually due to its lack of
> buffering I couldn't say, though I suspect it is. And something
Liam, if I read you correctly, you're suggesting that most contemporary
papers are buffered... Can you tell this with a pH pen? Light
Impressions for instance sells one that you can mark the paper with, the
color shows pH -- presumably giving, or suggesting, that info.
I have a bunch of paper about 70 years old -- a Strathmore drawing paper
that was "prewar" (pre world war 2), bought out of a warehouse by NY
Central & put into pads. It's great for cyano and VDB -- and SURELY is
unbuffered. (When did they start doing that??) If there's some simple test
I can do on that with cyano, let me know... But I mention that during all
this discussion I kept thinking that one hallmark of fixing VDB is
ALWAYS, on every paper, the INSTANT you put it in the fixer, even old,
weak, contaminated fixer, it simply POPS into a MUCH darker color.
That's the very dilute sodium thio in water.... What if anything does that
say about whether it's sulfiding or fixing?
J.
> interesting: when a fixed and (fairly briefly) washed VDB was put in sepia
> toner (as above), the shadows darkened quite quickly and the image tone
> gradually became cooler. No bleach was used before the toner.
>
>
> Liam
>
> -----Original Message-----
> From: rurmonas@senet.com.au [mailto:rurmonas@senet.com.au]
> Sent: 05 December 2002 09:45
> To: alt-photo-process-l@usask.ca
> Subject: VDB test results - part 1
>
>
> Last night I ran some tests on the the need for fixing with
> VDB. For the impatient, just read the conclusion below.
>
> I used 3 types of paper (Rising Stonehenge, Canson Cartridge,
> Canson Colorline). The reason for choosing three was to get a
> spread of clearing behaviour. Stonehenge clears easily, the cartridge
> clears more slowly, and the Colorline shows a slight stain even after
> extended washing. I took two pieces of each and coated about
> 2/3 of the surface of each. The uncoated section was to help
> judge any staining later in the test. These were dried with cool
> fan blown air.
>
> One set of three papers was washed for a total of ten minutes.
> First for two minutes with continuous aggitation, then in
> two changes of water for 4 minutes each with intermittent
> aggitation. All water used for the above was tap water with
> a pinch of citric acid added to ensure it was close to neutral
> pH. The second set of three papers were washed for 2 minutes
> with continuous aggitation. This was in water which had been
> filtered through both mechanical and carbon filters.
>
> After the washing I examined the paper (while still wet).
> As expected both Stonehenge had no visible stain. The cartridge
> after 10 min wash was clean, but after 2 min wash showed a very slight
> amount of stain. The Colorline showed slight stain in both samples.
>
> I then placed the paper into Agfa New Viradon (polysulphide) toner.
> All papers darkened very quickly. I continued to tone for 10 minutes,
> then washed and air dried the paper.
>
> All papers showed significant brown colouration on the coated part.
> This was about the same as "mid tone" on a VBD. Interestingly
> the colour is close to that of a normal VBD, unlike the yellow-brown
> that resulted from trying to tone a fully processed VDB print.
> The papers which had been washed for 10 minutes were slightly
> less dark than those washed for 2 minutes. This suggests the
> silver content could be removed by washing alone, but I suspect
> it would take hours to acheive this. The degree of staining was
> different between the three papers, but in all cases was significant.
>
>
>
> CONCLUSION
>
> VDB prints contain signifiacnt amounts of silver in unexposed regions
> after washing. This is true regardless if any visual staining is
> present or not. VBD prints need to be fixed. I suspect the minimum
> fixing time will probably vary with paper etc.
>
>
> Richard
> ---
> Richard Urmonas
> rurmonas@senet.com.au
>
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