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.