[pure-silver] Re: Old Paper Developer Question
----- 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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