[pure-silver] Re: Old Paper Developer Question
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Mon, 18 Feb 2008 18:07:23 -0800
----- Original Message -----
From: "Bogdan Karasek" <bkarasek@xxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Monday, February 18, 2008 5:27 PM
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:
I don't have Grant Haist's book at hand but I think this
is not too far off. Make up a stock solution of 0.2%
benzotriazole (2 grams per liter of water). At this dilution
the chemical will dissolve without problems. Use anywhere
from about 15 ml to perhaps 500ml of this solution to a
liter of working solution developer. When mixing up the
Dektol working solution with large amounts of the anti-fog
just replace some of the water used to dilute it with the
solution.
It will take some experimenting to find out the correct
amount. Somewhat less is needed for film. I don't remember
the amounts but around 5ml per liter should be a good
starting amount. Note that any anti-foggant will lower the
effective speed of the material. In fact, fog does this. In
negative film one can often get around a reasonable amount
of fog by simply increasing exposure. The overall density is
greater but the fog will not destroy the shadow detail.
Since the highlights of a print must be clear this technique
won't help so an anti-fog is necessary.
Benzotriazole is supposed to have less effect on paper
or film speed than bromide but large amounts of bromide, 15
grams per liter or more, can be used in developers like
Dektol to suppress fog. This will result in noticably lower
paper speed and may affect the image color (warmer). If you
have bromide in stock but not benzotriazole try the bromide
first to see if it will do.
Both bromide and benzotriazole are sensitive to pH but
work with ordinary film and paper developers.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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