Can leaving a print in fixer too long cause damage/staining?

Question

This is a question for you oldskool B&W photographers, I'm hoping there's some of you out there ;)

I am just getting round to sorting out my darkroom and thought I'd give it a test run now the power was in. The first thing I wanted to test was that the old paper I was given still worked, if only for testing even if not final prints. Freshly opened I developed an unexposed piece and all was well. I then made a few test contact sheets and although overexposed because I didn't eyt know the speed of the paper, all developed well.

I then made a couple of test prints, which looked fine in the darkroom but having removed them and seeing them in normal light, the edges of the paper had brown discolouration. The test contacts I had made previously were perfectly fine.

Now I know the paper is old so there's a possibility it is this, but given that the top sheets of paper, which are the most likely to have reacted with the packaging were fine, this seems less likely than I first thought. There's also the chance of the fixer getting exhausted, and I'll have to check this at a later date.

The main difference between the test contact sheets and the prints I made was that because I knew I was throwing the contacts away I didn't leave them in the fixer very long. Being an amateur who has only had a few evening classes in the darkroom I was under the assumption that fixer is harmless, and the longer you leave the prints in the fix the better, so that is what I did for the prints. Given that it is Ilford Rapid Fixer I have they were in there for long over the recommended time, which I had assumed was a minimum for safe fixing.

So my question, could the excessive time I leave a print in the fixer have negative effects on the print to cause this brown staining around the edge?

Answer 1

The answer is yes, although you must have left the prints in the fixer for quite a while to see the staining immediately. It's usually something that creeps in over time. It may be the case that your paper has oxidized from the edges inward before you used it, but you can check that by simply wasting a sheet and processing it "by the clock" (without exposing it, so you can eliminate as many variables as possible).

The length of time in the fixer isn't super-critical or anything. It's only the developer that you've got to get bang on; the stop bath and the fixer are (as you surmised) more or less a meet-the-minimum sort of thing. But the fixer is reactive, and for prints that are meant to last more than a very short time, it's something you want to get rid of. Otherwise you'll get that loverly yellow/brown patina of age in a hurry without the bother of toning.

In a typical "intro to the darkroom" course, you'll be shown the things that are necessary to make magic happen -- straight develop/stop/fix. And if you were shooting old-tyme news photos in the Weegee style to get something to the prepress guys, that's all you'd need. But if you want prints to last for any time at all, there's still a step to go, and that's to get rid of all of the residual chemistry (mostly the hypo/fixer). Your prints need at least a wash in running water -- how long depends on whether the paper is fiber-based (long time -- typically five minutes or more) or resin (shorter, since the "paper" itself doesn't absorb much and you only need to "clear" the emulsion). A hypo-clearing rinse (compatible with your fixer, of course) before the wash can speed the process up considerably.

An "archival" print washer is fairly cheap and easy to make if you can't pick one up cheaply enough. There are several DIY solutions online -- just search for "archival print washer". Both the "cascade" and the "upflow" desgns are effective; pick whatever looks easiest to make to you.

Answer 2

Suitable fixing agents must dissolve the silver halide contained in the emulsion. This must be compete, should any remain, they self-reduce, in time and blacken. The fixer causes the silver halides to become salts and must remain stable when diluted so they can’t decompose during the following washing step. The fixer must not attach the gelatin that is the binder of the emulsion. The fixer must not affect seriously the tufts of silver that comprise the image. Only two solutions meet these criteria -- Sodium thiosulfate and ammonium thiosulfate.

All of the above specifications are timed reactions. Fixers using the ammonium thiosulfate ingredient became possible when this chemical became available in a crystalline form. This formulation works twice as fast as sodium thiosulfate, thus the nickname “rapid fix”.

Nowadays, the rapid fix formula is almost exclusively used. Because its activity is very energetic, films and papers left in the fixer, particularly when fresh, begin to attach the silver that comprises the image. This effect is more prevalent with fine-grained films and the tufts of silver are petite.

Kodak recommends that their rapid fix be diluted with water for use, three parts water for film and seven parts water for paper. This is because photo papers contain about half as must silver as compared to film. This is because prints are viewed by reflected light. Light from a nearby lamp plays on the paper print. This light traverses the emulsion, hits a undercoat consisting ofbarium sulfate (baryta). This reflective layer redirects the illuminating light so it again traverses the emulsion. In other words, the viewing light makes two transits thus the amount of silver needed to form an image is reduced. Thus prolonged fix soaks effect paper prints to a greater degree than film.

Generalizations regarding fix times: Papers 45 to 70 seconds - Negative film emulsions 2 to 7 minutes. Time in solution is variable based on the thickness of the emulsion.