[pure-silver] Re: Development modifications for higher sharpness

From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
Subject: [pure-silver] Re: Development modifications for higher sharpness
Date: Wed, 27 Apr 2005 20:25:41 -0700

> One reason for the addition is to suppress the effects of bending or
> abrasion (this is from Mees I think. After reading this stuff for
> decades I can't always remember exactly where I've seen something).

Besides your postings, I have not seen any plausible statement or
explanation of a developer formulation influencing the pressure
sensitivity of som emulsions. I personally believe that iodide in the
developer and pressure sensitivity are unrelated, at least for
practical purposes.

>    If Iodide tended to prevent edge/border effects in older 
> type emulsions that could explain its presence in this 
> formula. I also have a very vague memory of reading that 
> Iodide could concentrate development near the surface of the 
> film. Again, if this is so it would be reasonable for the 
> applications above where maximum _resolution_ and minimum 
> distortion of the image are important.

I have not seen any statement or explanations for what you assumed in
two if-statements. In particular I don't think the latter is very
plausible.

>    All of this may be obviated in modern thin emulsions.

In modern emulsions, pressure sensitivity is dealt with by making
crystals with fewer lattice defects. One good example is enlarging
papers made for roller transport processors. (For that applications,
an anti-staining agent, which is a physical development retarder that
does not retard development nor hinder fixation, in the developer is
also important in obtaining clean prints.)

--
Ryuji Suzuki
"Keep a good head and always carry a light camera."
=============================================================================================================
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.

Other related posts: