[pure-silver] Re: Fixing time for fiber
- From: titrisol <titrisol@xxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Fri, 10 Aug 2007 00:33:55 -0700 (PDT)
Could there be sulfinding in the hypo-clear?
Are you replacing the water in the "waiting" bath every so
often?
I know sometimes fixer smells like sulfide, and that could casue
some yellowing, but also sulfite can convert into sulfide?
--- Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote:
>
> ----- Original Message -----
> From: "Eric Nelson" <emanmb@xxxxxxxxx>
> To: <pure-silver@xxxxxxxxxxxxx>
> Sent: Thursday, August 09, 2007 9:06 PM
> Subject: [pure-silver] Re: Fixing time for fiber
>
>
> > Eric,
> > Are you talking about stop bath that is too weak to
> > acidify the print, thereby shortening the life or
> > activity of the fixer? Or just not draining the print
> > long enough before it hits the stop?
> > Eric
> >
> > --- EJ Neilsen <ej@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> >
>
> Stop bath will immediately stop development and
> inactivate the developer. A 30 second soak will also wash
> out much of the developer. Standard acid hardening fixing
> baths are designed to withstand a considerable amount of
> carried over developer since most of them were designed in
> the 1930s when many photographers did not stop baths. A
> standard fixing bath like Kodak F-5 or Kodak packaged fixer,
> is well buffered using and also contains an excess of Sodium
> Sulfite. The Sulfite serves two purposes: first, it prevents
> the decomposition of the Thiosulfate by the acid, and
> secondly, it prevents staining from carried over developer.
> If the fixing bath is neutral or alkaline its possible
> for the developer to reactivate in the fixing bath. If there
> is enough sulfite it may not cause the usual yellow stain
> but can produce dichroic fog from deposits of metallic
> silver on the surface of the print. This is caused by the
> developer reacting with dissolved halide complexes in the
> fixing bath. A fixer, even if alkaline, would have to be
> close to exhaustion for this to happen, unless it was made
> without sulfite or with very little sulfite.
> From the description of the original problem I do not
> think it was caused by developer stain. That usually shows
> up very quickly, sometimes immediately after fixing. More
> likely it was caused by sulfiding of the image from somthing
> in the atmosphere. Untoned prints are quite vulnerable to
> this and to oxidizing. Oxidizing usually is manifested as
> silvering out, that is, the production of a black stain or
> even a mirror-like deposit over high density areas.
> Sulfiding causes the image to turn brown or yellow.
> Sometimes the sulfide migrates but usually not.
> There is a limited amount of protection of the image if a
> very small amount of Thiosulfate is allowed to remain in the
> emulsion. The amount is very small, a larger amount causing
> the usual staining. However, the current Kodak and other
> recommendations for washing and for the use of a wash aid
> reflect this fact. If a print or film is washed to the point
> where there is no thiosulfatge whatever in it toning becomes
> absolutely necessary to protect the image.
> Display prints should always be toned to prevent attack
> by airborne polutants. Effective protective toners include
> all sulfiding toners, Selenium when it is carried out far
> enough, and Gold toners. Gold is very effective and results
> in a cold or neutral image for many papers but is too
> expensive to be used routinely.
> Some sulfiding toners can not be used for partial toning
> because they do not tone the image uniformly. Full toning
> with any of them results in very permanent images but they
> will be the usual Sepia color.
> Stabilizing agents like Agfa Sistan and Fuji Ag-Guard are
> effective but not as much as a toner. If its absolutely
> necessary that the image color and density not be changed
> one of these may be useful. While not as effective as a
> toner they will nonetheless give significant protection
> where a print must be displayed or stored under adverse
> conditions.
>
> ---
> 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.
>
____________________________________________________________________________________
Pinpoint customers who are looking for what you sell.
http://searchmarketing.yahoo.com/
=============================================================================================================
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:
