rurmonas@senet.com.au
Date: 12/06/02-10:49:31 AM Z
Quoting Liam Lawless <liam.lawless@blueyonder.co.uk>:
> We've come a long way from the original question
Yes we have, time to wrap this up. I will post a conclusion seperately.
> My point about hypo and cyano was that hypo might be a more efficient
> developer (i.e. giving a stronger image) that has been overlooked because
> water works so well. On the other hand, maybe not - I don't know.
True, I will need to try it one of these days.
> But the fact remains that we've both witnessed VDB change in
> alk. thiourea. If we don't believe that's due to silver sulphiding, maybe
> we should be checking whether residual iron remains after fixing and forms
> ferrous sulphide in the toner.
That is where I am heading, but I have realised that it is irrelevant to
answering the original question. That was regarding the permanence of VDB.
The fact that we have both observed a change with relatively simple
chemical actions suggests that a VDB print has some active components
and thus has cannot be truly permanent.
> I'm quite sure I've printed out f.a.c. and developed with gold chloride, but
> my memory isn't what it was (I'm over 40, you know). However, I've just
> come back from the kitchen where I developed a dirty yellow f.a.c. image in
> ferricyanide and DID get an image in Prussian blue. Two suggestions: on its
> own, f.a.c. needs a lot of exposure, on a par with cyanotype, and secondly,
> I used strongish solutions (f.a.c. 18%; pot. ferri. about 10%).
Yes I am aware of this. I keep meaning to try printing FAC and developing
in ferricyanide. I should have been clearer with my description of
the "dirty yellow image". This was exposed and thoroughly washed (about
20 min. wash). It does not form a blue image. I am beggining to think
it may be a "stain" in the paper, the same way rust or ferric chloride
can stain clothing / skin. This would explain the apparent lack of
reactivity.
Thank you for running through the investigation with me. It has
certainly been interesting, and I have learned more about VDB.
Richard
--- Richard Urmonas rurmonas@senet.com.au Richard --- Richard Urmonas rurmonas@senet.com.au ------------------------------------------------- This mail sent through SE Net Webmail http://webmail.senet.com.au
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