AFAIK, most fixers are acid. A few people, however, swear on alkaline fixer. This makes me wonder why. I have heard arguments like alkaline fixers being gentler to the emulsion and causing less of a shift in image tone. I also know that acid in the paper will impair its archival qualities. That much of it sounds great.

I think the usual acid fixer has an advantage, too: I have read that in an acid environment, the pores of the paper close, and gelatin will swell more reluctantly. Therefore, if you use acid stop and acid fix, this should prevent the fixer from penetrating too deeply into the paper base. If you then use an alkaline wash aid (soda, sodium sulphite, or prefab stuff), the pores open again, and whatever is in there, can be washed out more easily, provided it is soluble. And that's where I see the problem: Acc. to what I have learnt, developer and stop will readily dissolve and thus be washed out quickly and practically completely. Fixer, however, may contain problematic compounds, i.e. complexes that are not easily washed out of the paper, if the silver content becomes to high.

Is anyone aware of investigation results pertinent to this problem?

Is there any information on the compatibility of rapid washing (such as Ilford's sequence) with alkaline fixing?

-- Thomas Wollstein (thomas_wollstein@web.de), May 04, 2000

Answers

Great question Thomas! I am not aware of any studies regarding this subject. More than one person on this forum has recommended an alkaline fixer and a water stop bath for PMK, stating that the acid stop and acid fix reduces the staining action of PMK. However, I have not altered my standard procedures for processing PMK and I don't seem to have a problem getting stain. I have also heard people saying that alterning the pH of the stop and fix changes the way papers respond to toner--I'd be very interested to hear some details on this subject.

-- Ed Buffaloe (edbuffaloe@unblinkingeye.com), May 04, 2000.

Formulary's TF-4 Rapid Fixer is an alkaline fixer (according to what I was told by one of their technical advisors). This fixer is compatible with rapid washing. A problem can occur, however, if you are using a selenium toner, because this introduces, as part of its composition, an acid-based fixer -- thus you have to go through the washing sequence again, using a hypo-clearing agent either mixed with the toner or after toning. This technical advisor suggested gold toning because there is no reintroduction of fixer.

-- Christopher Hargens (ldmr@cruzio.com), May 04, 2000.

Toning problems aside, I'm not sure what real advantage an alkali fixer would have. If the emulsion isn't hardened then its archival permanence will be adversely affected, leaving it much more vulnerable to atmospheric pollution and fungal attack. I should think this would outweigh any slight menace from acid paper. Besides, the archival permanence of acid-fixed and hardened prints is well known and proven; that of alkali fixed prints is all theory.

The only hardening agent I know of that will work in an alkaline solution is Formalin (Formaldehyde solution), and this isn't a very nice chemical to work with.

-- Pete Andrews (p.l.andrews@bham.ac.uk), May 05, 2000.

Fixer, however, may contain problematic compounds, i.e. complexes that are not easily washed out of the paper, if the silver content becomes to high.

Use a two bath fix and you won't have this problem.

If the emulsion isn't hardened then its archival permanence will be adversely affected, leaving it much more vulnerable to atmospheric pollution and fungal attack.

Do you have a reference for this? Everything I've read from the manufacturers and researchers recommends against hardening prints, because it makes it harder to wash out fixer.

-- Tim Brown (brownt@ase.com), May 08, 2000.

Tim

I am aware of the advantages of two-bath fixing (and have been using it for a couple of years, but the argument can be given for both alkaline an acid fixers. So I think it doesn't answer my question why alkaline fixing is supposed to be beneficial.

-- Thomas Wollstein (thomas_wollstein@web.de), May 09, 2000.

<<<<<>>>>

This information is totally incorrect. Hardening has nothing to do with archival perfomance. In fact once a neg or print is dry the effect of hardener is nil, hardener only "does its job" while the emulsion is wet. Worse for prints is that the use of a hardening fixer complicates and extends the washing process.

You may be getting mixed up with selenium which does indeed protect against atmospheric pollution. However, I know of know commonly used processing chemical that protects against fungal attack.

Mark

-- Mark Bau (markbau@altavista.com), May 09, 2000.

Thomas, I can't put any good authority behind this, but I recall having read something to this effect: some thiosulfate adsorbs to both silver image and to "sizing" used in the paper (other literature has indicated that the sizing tends to block diffusion of thiosulfate thru the paper fiber cell walls). For some reason, the adsorption tendency was much less in an alkaline fixer; thus washing would proceed much faster and residual hypo levels could be easily brought real low, even in the absence of a hypo eliminator.

This is based on my fuzzy memory with no good explanation for the mechanisms; I only posted to suggest a topic to research. I don't believe emulsion swelling due to pH is the major factor in this case.

-- Plutoo (bcarriel@cpicorp.com), May 09, 2000.

> I recall having read something to this effect

I read it too; I _think_ it came from Bill Troop, but I don't recall any evidence or references presented to back up the assertion.

-- John Hicks (jbh@magicnet.net), May 09, 2000.

In fact once a neg or print is dry the effect of hardener is nil, hardener only "does its job" while the emulsion is wet.

If that was really the case there would be absolutely no point in using a hardener. Hardening has the effect of partially polymerising gelatine, making it more resisitant to mechanical damage, and lowering the residual water content of the emulsion. Since most fungi need water to proliferate, and untreated gelatine is a very good fungal nutrient, it seems perfectly logical that hardening will increase resistance to fungal attack. By the same token the emulsion is made less porous, and less likely to take up atmospheric pollutants.

Most of the residual chemicals from insufficient washing are left in the paper base of the print, not the emulsion. This is the sole reason why RC paper can be processed more quickly; the base is non-absorbent. The fact that a hardened emulsion takes longer to wash shouldn't be any reason for abandoning the longer term advantage of hardening.

-- Pete Andrews (p.l.andrews@bham.ac.uk), May 15, 2000.

Here's the advantages of an alkalai fixer:

1. You keep the whole process alkaline or neutral. This is less of a shock to the emulsion.

2. The alkaine fixer fixes incredibly fast: my films clear in less than 30 seconds.

3. Alkaline fixers are more soluble, so they wash out faster. I don't know if this is the fixer itself or that the fixer doesn't produce the byproducts during fixing are more soluble. It really doesn't matter. You just don't need to wash as long.

4. Alkaline fixers have high capacity.

After one use of Photographer's Formulary T4 Fixer, I'm a complete convert.

I tried this fixer because of a strong recommendation in Steve Anchell & Bill Troop's Film Developing Cookbook. Anyone getting as deep into the photographic process as this thread needs this book.

Here are problems I've encountered with acid fixers. Alkaline fixers don't result in these problems.

1. Pinholes. When the alkaine developer hits an acid gas is released as part of the chemical reaction. A water bath after the developer reduces the chances, but an acid fixer can still cause this problem.

2. Soft emulsion: the first time I tray developed an 8x10 negative everything was fine till the negative hit the fixer. The emulsion then got soft, and I gouged it with my fingers (not fingernails). I could feel the emulsion change as it went in the fixer. Films coming out of the alkaline fixers seem as hard as in the developer.

-- Charlie Strack (charlie_strack@sti.com), May 19, 2000.