This is not an attempt to contradict your statement but I was surprised at how little fixing time appears to be needed according to this video by John Finch. The relevant section is from 4 mins 15 secs
pentaxuser
This is not an attempt to contradict your statement but I was surprised at how little fixing time appears to be needed according to this video by John Finch. The relevant section is from 4 mins 15 secsFixing too short is always worse, because this may leave poorly soluble Silver Thiosulfate salts in the emulsion, which will not wash out.
Be careful with C41RA fixer, it is very powerful and extremely fast. I check it recently, a test strip of Foma 400 in the normal C41 working solution was totally clear in 10-15 seconds at room temperature. The risk of overfixing and other potential problems with B/W films could be in the range of just one minute more than neccesary. I used 60 seconds with Foma 400 and film looked ok to me.
Makes sense since it has to fix 3 times the amount of black and white.
To my surprise, the negatives look ok.
How would a photographer in his home darkroom determine, both for film and prints, whether he over-fixed or under-washed?
How would a photographer in his home darkroom determine, both for film and prints, whether he over-fixed or under-washed?
Many here love fat negatives (yes, I plead guilty)
I once left a B&W print in Agfa 304 fixer (which is very acidic, pH slightly above 4) for about 2 hours (stepped out of the dark room and forgot). The paper curled up, which caused the center part of the print to stick out of the fixer bath. Result: center part looked normal, left and right hand side of print looked seriously bleached.
There are some reasons, why few people ever notice over fixation and bleaching:
- It typically happens uniformly and is therefore much less noticeable than my dark room blunder.
- It doesn't happen with neutral or alkaline fixers, even after hours. BTDT.
- We study prints in wet state, but prints tend to get darker when they dry (dry down effect), so in many cases uniform bleaching through fixer is a welcome effect.
- Many here love fat negatives (yes, I plead guilty), which can also only benefit from bleaching in the fixer.
Many here love fat negatives (yes, I plead guilty), which can also only benefit from bleaching in the fixer.
Whereas my preferences tend toward the "thin" negative, which may explain my outlook on the issue.Let me join you in that particular corner of shame.
There is no standard process for "bleaching B&W paper in fixer". Bleaching speed strongly depends on fixer pH (which can in turn change with stop bath carryover - or developer carryover) and fixer strength/exhaustion. If you are unsure, take a fixed print and dip it halfway into your test fixer. Take note, when visible bleaching has occurred and fix your prints for less than that.
Having you ever performed the test you suggested? If so, at approximately what time did bleaching become visible? If not, have you ever experienced bleaching through overfixing on your own prints. If so, what fixer and dilution were you using, and how long were you fixing for?
He did experience it, read more of the thread above.
The test for inadequate washing is the Kodak HT-2 test for residual hypo. Cruise on over to unblinkingeye.com for the formula and the pdf (or jpeg?) of the comparison strip.How would a photographer in his home darkroom determine, both for film and prints, whether he over-fixed or under-washed?
I did. He said he left a print in the fixer for two hours and a portion of the print was bleached. Two hours.
It’s not clear to me what you want. Do you want to know the answer or are these rhetorical questions? If you want to know the answer, testing it seems reasonable, right? If it’s rhetorical as in, nobody should leave their prints in so long, then yes, we all agree.
Why don't you let Rudeofus answer the questions I asked him? He is the one who appears to have the most information on the topic of overfixing. Perhaps we will both learn something.
My information about overfixing is restricted to one dark room blunder, which is not a whole lot in the grand scheme of things. It involved a very acidic fixer (Agfa 304) and a fixing time, which none would ever knowingly chose (around 2 hours). I am confident, that I left prints in neutral fixer (which I have used ever since) longer than I should have, and the bleaching, if there was any, was very uniform and/or very weak - I did not notice a thing. I did not perform the thorough test as suggested by Doremus, but I took Ron's word, that neutral fixers "don't bleach". If you ever observed my sloppy and careless work, you'd quickly come to the conclusion, that a D=0.05 difference does not make much of a difference in my work flow.
Since more or less all fixers were "very acidic" 50 years ago, and since most subject related photographic literature comes from that time, the "bleaching through extended fixer time" theme is maybe more emphasized, than modern neutral fixers would warrant.
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