-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx [mailto:pure-silver-
bounce@xxxxxxxxxxxxx] On Behalf Of Bogdan Karasek
Sent: dinsdag 19 februari 2008 2:27
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Old Paper Developer Question
Hi,
Off hand, how much Benzotriazole should be added to Dektol to prevent
fogging. Several months ago, I was given some old printing paper by my
neighbor prior to his return to Switzerland. He had kept it in a dry
place for at least 20 years.
What would be a good ballpark figure for adding Benzotriazole to Dektol,
in order to get me started and I can experiment from there.
How many grams per litre of 1:2 Dektol?
Cheers,
Bogdan
Richard Knoppow wrote:
----- Original Message ----- From: "Don Sweet" <don@xxxxxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Sunday, February 17, 2008 9:13 PM
Subject: [pure-silver] Old Paper Developer Question
I have few boxes of 25+ year old enlarging paper, including Ilfobrom and
Portriga Rapid. It is unopened, so I decided before blazing away I
should look for some information about how to best to process it,
particularly to minimise fog. First I sourced some benzotriazole which I
thought could just be added to Dektol or Neutol or Bromophen developer.
Then following links from the UnblinkingEye website I found some
suggestions that both amidol-based or glycin-based developers are more
resistant to fog than the usual MQ or PQ blends. Does anyone know if
that is right, and whether either of them is likely to be a better
developer for my old paper?
Thanks
Don Sweet
The fog in old paper or film comes from a chemical change in the
emulsion. I think the advice about Glycin or Amidol may come from some
confusion about the type of fog here. Some developers are less likely to
cause fog themselves than others and don't need as much anti-fog.
However, this is also dependant on pH. Some low activity film
developers, like D-76 and D-23 don't produce enough fogging to require
an antifoggant although fresh D-76 will produce a slight amount of fog.
Higher pH developers of the sort usually used for print developing
nearly always need some anti-foggant. This is also because fog is not
tolerable in prints but can be tollerated in film if not too great.
Benzotriazole is more effective in reducing fog in old paper than
bromide although bromide often works. Benzotriazole also tends to
produce cold images where bromide tends to warm them up. Usually
benzotriazle will result in less loss of speed.
Grant Haist has a chart in his book showing approximate amounts of a
benzotriazole solution to add to developers for different amounts of
fog. Be aware than if the fog is bad enough no anti-foggant can fix it.
Also, the antifoggant will affect the paper curve a bit so it won't look
quite the same.
Plain Dektol or Bromophen or any other standard paper developer works
fine with this stuff.
Unfortunately, my copy of Haists' book is boxed up at the moment.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
==========================================================================
===================================
To unsubscribe from this list, go to www.freelists.org and logon to your
account (the same e-mail address and password you set-up when you
subscribed,) and unsubscribe from there.
--
________________________________________________________________
Bogdan Karasek
Montréal, Québec bogdan@xxxxxxxxxxxxxxx
Canada www.bogdanphoto.com
"I bear witness"
________________________________________________________________
==========================================================================
===================================
To unsubscribe from this list, go to www.freelists.org and logon to your
account (the same e-mail address and password you set-up when you
subscribed,) and unsubscribe from there.
