Fixer times for papergreenspun.com : LUSENET : B&W Photo - Printing & Finishing : One Thread
How do I know how long the paper must be in the fixer? Is there a method I can learn? Are there different times for bromide and chlorbromide papers? I'm thinking about mixing my own fixer from recipies. Sodium based.
-- Patric (firstname.lastname@example.org), June 19, 2001
For a sodium thiosulfate fixer, I would use two baths and give the paper 5 minutes in each. There should be no difference between bromide and chloride papers.
-- Ed Buffaloe (email@example.com), June 19, 2001.
I use Ilfords proven two bath archival method. One minute in each bath. Has worked with little residual fix left in the paper. The reason is that there is enough time to fix the silver in the emulsion but not enough to soak into the paper. james
-- james (firstname.lastname@example.org), June 19, 2001.
Patric, are you looking for basic information or a more advanced test method? If you'd like to test your own specific combinations, from my fuzzy memory, here's a method I've read about (don't remember where; probably either Ctein or Richard Henry); the principles are sound so it should be a good test.
You are maybe familiar with a method to find FILM fix times, whereby you dip a piece of unprocessed film in the fixer and measure the clearing time. Then you fix for 2 or 3 times that long. The method for paper is somewhat similar, except you can't look at blank paper and know when all of the silver halide has been removed.
So the way you do this for paper is to get a test strip of paper and process it like so: 1) Skip the developer 2) Go into your stop batch (or water or whatever you use) for about ½ minute or so. 3) Put only about the first one inch into fixer; after about 10 seconds submerge another inch, etc, etc. Your fixer test strip now has parts that were fixed for 10 seconds, 20 seconds, 30 seconds, etc. 4) Put the test strip into running water to quickly rinse the fixer out. 5) Finally, put the test strip into DEVELOPER and turn on the lights. After a minute or two in developer, rinse it off again.
How to evaluate: the developer has actually developed an "image" anywhere silver halide was left over. So the first pure white patch is the shortest time for complete fixing. Using the same rule of thumb as for film, at least double that time for fixing. Again, I haven't done this but I am real confident it will be a good test.
Any feedback from someone who HAS used such a method? If using ammonium thiosulfate style, fixing should be much faster, you might want to test with shorter intervals. It would be interesting to see how much safety factor the Ilford "rapid method" has with different papers.
-- bill C (email@example.com), June 19, 2001.
"I use Ilfords proven two bath archival method. One minute in each bath", as posted above. This method has been proven by whom? Some B&W film & paper scientists don't believe the short times with the concentrated developer adequately fix all papers. This is why some of us still use the older 'paper strength fixer' in a two bath system rather than the newer-shorter times.
-- Dan Smith (firstname.lastname@example.org), June 20, 2001.
I have to agree wholeheatedly with Dan.
"If it ain't bust, don't fix it." is a very good adage. (Oops, just realised, it's also a very poor pun in this context too!)
Longer fixing times have been time proven to work, and the recommended times always used to be at least 3 minutes in rapid fixer, and up to 10 minutes in standard Hypo with FB paper. Now as far as I can tell, the formulation of fixer hasn't changed much, and FB paper is (arguably) much the same as it always was. So why has it suddenly been decided that fixing (and washing) times should be a lot shorter?
I'd take "scientific" accelerated ageing tests with a big pinch of salt. Ask Epson how reliable they are!
-- Pete Andrews (email@example.com), June 20, 2001.
I have tested most of the FB papers I use with Kodak Residual Silver Test Solution ST-1 after fixing with the Ilford archival method (I use 2 fix solutions for 45-60 seconds each) and am quite satisfied that the papers are adequately fixed. I have extended the recommended time just to make sure. I have 10 year-old prints fixed by this method hanging on the wall with no image degradation, whereas I have had prints that were inadequately fixed that showed deterioration within 5 years.
-- Ed Buffaloe (firstname.lastname@example.org), June 20, 2001.
Its probably a good idea to use the following and test both for presence of residual silver (i.e., insufficient fixing) and for residual hypo (i.e., insufficient washing). A residual silver test solution consists of 100 ml water with 7.5 gms of sodium sulfide (not sulfite). Place the solution in a clear area of the print and wait 5 minutes. A brown stain indicates residual silver (i.e., insufficient fixation). You can use Kodak's HT2 for a test of residual hypo - HT2 has 7.5 gms of silver nitrate and 125ml of 28% acetic acid and water to a litre. Place a drop on a blank piece of paper that has been washed with the other prints, flush with a salt water solution after 2 minutes. Anything more than a light yellow stain indicates residual hypo (i.e., insufficient washing).
And my experience parallels Ed's. The Ilford sequence seems to work as well as the traditional one - so where did the traditional recommendations come from? Anyone's guess, I guess - but my speculation is that tradition tends to err on the conservative side. Underfixing is obviously problematic and it seems logical to fix long enough to be on the safe side. Its only subsequently that issues like removal of hypo and water conservation cropped up. Also, while it is 'proven' that the tradition method fixes adequately, I haven't seen proof anywhere that it is the 'bare minimum time' necessary for adequate fixation. I guess eventually, like all things photographic, it is a tradeoff - between surety of adequate fixing and surety of adequate washing. I'm pretty sure I also saw some evidence that trace amounts of residual hypo help print longevity (but I don't recollect where I saw this, maybe Wilhelm?) - so that might push one towards longer fixing times again.
-- N Dhananjay (email@example.com), June 20, 2001.
I have an article on archival processing at http://unblinkingeye.com/Articles/Archival/archival.html, where I try to present the most current information. I found quotes from Doug Nishimura of RIT's Image Permanance Institute stating that very small amounts of residual thiosulfate do seem to improve image permanence. The problem is that there is no easy way to tell when you have the correct amount. The standard test for residual thiosulfate (methylene blue) is time consuming and requires an accurately calibrated densitometer. The IPI recommends intentional sulfiding of images for greatest longevity (the easiest way to do that for papers is to tone in brown or sepia toner). We've discussed all this before--I'm indebted to John Hicks for pointing out the information from Nishimura. The IPI studies were for microfilm, which is of critical concern to libraries and archives, but the information is also quite relevant to us fine art photographers. I wrote to Doug Nishimura and asked him to address our concerns regarding fiber based papers, but never received a reply from him.
-- Ed Buffaloe (firstname.lastname@example.org), June 20, 2001.
Thanks a lot for the information everyone! I have always used rapid fixers from different brands, but now when I've started to mix my own developers I thought I should mix the fixer too. :-)
-- Patric (email@example.com), June 20, 2001.
> I wrote to Doug Nishimura and asked him to address our concerns regarding fiber based papers, but never received a reply from him.
Richard Knoppow has been in contact with Doug Nishimura and posted several pages of info on rec.photo.darkroom a while back, maybe a year or so. I don't know Richard's address, but he's often found in rec.photo.darkroom and I'm sure he'd be glad to pass along the info to you.
-- John Hicks (firstname.lastname@example.org), June 20, 2001.
John, I believe I read one of his posts. I'll look him up. Thanks for the information--again. Ed
-- Ed Buffaloe (email@example.com), June 21, 2001.
even if the paper is fixed correctly by the ilford method, it still presents the problem of the margin of error being greatly enhanced. If I fix for 3min in a more dilute fix and overfix by an additional 10 secs,my margin of error is much lower than if I do a highly concentrated fix at 30 sec and overfix for the same 10 secs.
I am sure that all of us are very careful about our times in all chemicals, but accidents happen, why help them along?
Overfixing cannot be cured by overwashing, overfixing will cause the print to become brittle, usually causing print edges to chip off.
-- mark lindsey (firstname.lastname@example.org), June 23, 2001.