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

----- Original Message ----- 
From: "Ryuji Suzuki" <rs@xxxxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Wednesday, April 27, 2005 10:02 PM
Subject: [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

    It may not seem plausible but its what was stated in the 
older literature. Even if it never worked evidently the 
photo scientists of Mees's era believed it and added iodide 
for these reasons. I don't have the wherewithal to prove or 
disprove it. I could probably find the places I read it but 
it would take considerable time, not easy to set aside when 
I have a job and other things demanding it.
    Also, you don't seem to have gotten it that I was ASKING 
your opinion of these notions.
    Oy vey.

---
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.

Other related posts: