[pure-silver] Re: Yellow edges
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Wed, 25 May 2005 15:09:05 -0700
----- Original Message -----
From: "Ryuji Suzuki" <rs@xxxxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Wednesday, May 25, 2005 9:59 AM
Subject: [pure-silver] Re: Yellow edges
> From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
> Subject: [pure-silver] Re: Yellow edges
> Date: Mon, 23 May 2005 16:46:37 -0700
>
>> This is a better test than any test of the hypo itself
>> because it
>> shows if the hypo is working.
>
> That's an overstatement. Iodide precipitation test has its
> own
> advantage of being able to test the fixer solution at the
> beginning of
> each shift in roomlight, or without spending a lot of time
> to produce
> questionably fixed prints just for testing. The result of
> standard
> iodide precipitation test is conservative enough so that
> given enough
> fixing time prints are most likely fixed well enough not
> to cause
> positive results with sulfide or any other toner. I would
> rather
> recommend to spend same effort in more productive way, by
> toning all
> important prints. (and this may require to adjust printing
> to obtain
> the desired effect after toning.)
>
>> RC papers generally have thin emulsions so they fix
>> and
>> wash very rapidly.
>
> That's not the reason RC washes rapidly. Although some
> manufacturers
> use slightly different emulsions on RC and FB in the same
> product
> line, the fixing times are generally comparable and I
> don't see a
> general trend for the relation of emulsion "thickness"
> between
> different supports.
>
Yes, a mis-statement and I realized it after sending
this. I know that any differences in fixing time between RC
and fiber paper are due to different emulsions. All paper
emulsions are thin since light must pass through them twice.
My understanding is that fiber paper fixes out in about the
same time as RC.
As far as the Iodide precipition test, the iodide
precipition test needs to be done with some understanding of
the amount of dissolved silver it will indicate. If done
correctly, it will show partially exhausted fixer before it
stops fixing adequately. However, IMO, it can also be
misleading. The stain test is positive. It can be done with
a scrap of paper processed with the run of prints. If it
indicates inadequate fixing its possible to re-fix the batch
in a fresh fixer bath. Both tests have their places.
BTW, do you have any literature on the quantitive.
Another note on fixing times. Old handbooks often give
very long times for fixing, on the order of 15 or 20 minutes
for both film and paper. I think there are two reasons for
this. One was to try to insure complete fixing where
slopping processing practice was used. That is, many prints
in a tray with inadequate agitation and, perhaps, partially
exhausted fixer. The other reason is perhaps more obscure:
it is to insure complete _hardening_. Sometimes the hardener
took longer to work than the fixer took to fix.
I rather wonder how much other "conventional"
recommendations were based on trying to overcome expected
poor practice.
---
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:
