Fixing in table salt solution

Alan Johnson · Oct 5, 2013

http://www.flickr.com/groups/1924221@N25/discuss/72157629528867358/
I developed 2 test strips of Agfaphoto APX 100 for the same times in Fomadon Excel (similar to Xtol) at 23.5C.
One strip was stopped and fixed normally in proprietary chemicals.
The second strip was stopped with one wash of water at 27C then fixed for 24hrs @ 28 +/- 2 C in a solution comprising 150grams table salt in 600ml water.
The tank was kept in a warm cupboard (hot water cylinder) and agitated about every 2hrs except during 8 hrs when it was only agitated once.
Conclusion:
The print from the negative fixed in table salt solution is entirely satisfactory but held side by side with a print from the proprietary fixer negative it is slightly more grainy.
See scans of 0.1 in square sections of negative, processed identically.

pentaxuser · Oct 5, 2013

Interesting experiment. Apart from the apparent extra graininess, can you be sure that table salt has actually fixed the film permanently in the way that proprietary fixer does?

Thanks

pentaxuser

Light Guru · Oct 5, 2013

Why would you want to spend 24hours agitating every 2 hours to fix your film. It's not like buying fixer that will do the job in 5 minutes is expensive.

Alan Johnson · Oct 5, 2013

Hello PU,
I'm not familiar with the early work but here it is stated that Fox Talbot used a concentrated salt solution for fixing in his early work so yes I think fixing would be permanent:
http://www.flickr.com/groups/1924221@N25/discuss/72157629895741409/

Alan Johnson · Oct 5, 2013

Light Guru said:
Why would you want to spend 24hours agitating every 2 hours to fix your film. It's not like buying fixer that will do the job in 5 minutes is expensive.

LG,
It's part of my secret plan to promote film sales in parts of the world where photochemicals are not available.

removed account4 · Oct 5, 2013

hi alan

love this stuff

from what i remember talbot's salt fixer sometimes wasn't permanent, sometimes it worked, and othertimes he had "troubles" ...
( that is why he was turned on to hypo ) ..

what i was told about the salt fixer is that it "preserves" the image, and sometimes it doesn't, or fix it completely. i wish i could remember who told me
and where i read it, i'd link to it for you.

i think its great to have materials to light-fast things
and develop things that are in a lot of kitchens ... the darkroomexpermente did all sorts of tests
and developed film in shallots, as well as rosemary and also what seemed to be dinner ( salad )
now with a little salt its fixed

john

Amphetadream · Oct 5, 2013

I wonder if this would be useful for preserving solargraphs? Standard fixer pretty much ruins the image completely, and unfixed they are doomed to slowly fade away...

miha · Oct 5, 2013

Michael, but sodium thiosulfate is recommended for fixing T-grain films.

removed account4 · Oct 5, 2013

isn't ammonium thiosulfate usually recommended ( speed fixer ) for t grained films,
and fix times can sometimes still seem excessive in order to get the color tinge out of the film.
(tmy, tmx and tmz at least )

miha · Oct 5, 2013

Both are recommended, at least by Kodak, but ammonium thio is twice as fast.

Gerald C Koch · Oct 5, 2013

Talbot's paper negatives and prints were not fixed but merely stabilized. Examples of his work in the British Museum can only be viewed briefly in very dim light to prevent them from fading.

Sorry folks you still need to use thiosulfate or a similarly strong complexing agent.

Alan Johnson · Oct 5, 2013

If I may be granted a temporary indulgence to stray from the conventional, if there are no photochemicals available, film may be developed in Caffenol, fixed in salt and the image obtained on a mobile phone using the Lomography app for iphone or android, there are other similar apps.The image does not need to be archival on the film.Some countries with a different culture have mobile based banking systems.
I have not actually done this.

A-Shooter · Oct 6, 2013

The anti-caking agent in the table salt may give some fixing action depending on what agent is used. Some table salts contains small amounts of potassium or sodium thiocyanate. This is an express fixer agent. The amount in 150g salt used alone may fix he film in 10-15 minutes, but the salt really hampers the action.
So, no, salt doesn't work as a fixer. Get some ammonium thiosulfate and mix your own fixer. It can be bought on the net and shipped by mail. If you can't get it by mail, there is a great possibility that you cannot get film either. Problem solved.

Gerald C Koch · Oct 6, 2013

Has anyone thought to test the film for residual silver? If not then the results are meaningless. An improperly fixed negative will eventually fade.

Alan Johnson · Oct 6, 2013

My table salt has sodium hexacyanoferrate II as anti-caking agent. Still it's rather surprising if all those including Fox Talbot who used salt had cyano-derivatives in it.
I did check,for example, ebay India, film can be purchased shipped from the US but not fixer, it may be related to shipping cost.
I don't think Caffenol-table salt-mobile phone as a route into film photography would appeal to many on APUG but it is very low cost if you have the phone so just mention this route exists, a search reveals some recently tried caffenol-table salt.

pentaxuser · Oct 6, 2013

Gerald C Koch said:
Has anyone thought to test the film for residual silver? If not then the results are meaningless. An improperly fixed negative will eventually fade.

You've hit on a key question here, Gerald, as to salt's efficacy as a fixer. I look forward to somebody's test results.

pentaxuser

removed account4 · Oct 6, 2013

Alan Johnson said:
My table salt has sodium hexacyanoferrate II as anti-caking agent. Still it's rather surprising if all those including Fox Talbot who used salt had cyano-derivatives in it.
I did check,for example, ebay India, film can be purchased shipped from the US but not fixer, it may be related to shipping cost.
I don't think Caffenol-table salt-mobile phone as a route into film photography would appeal to many on APUG but it is very low cost if you have the phone so just mention this route exists, a search reveals some recently tried caffenol-table salt.

and current mobile phone cameras can create an image as good as some 35mm cameras ( 40mb files ) ...
i couldn't agree more alan!
john

cliveh · Oct 6, 2013

Guys, dont confuse Talbots early work with the later development of the Calotype. As Gerald points out Talbot used salt solution to stabilise his photogenic drawings not fix them. These were made with silver nitrate solution and a weak salt solution. AgN03 + NaCl = AgCl. Talbot noticed that without any stabilisation or fixing the image would fade more quickly at the edges of his prints (where he had brushed on less salt). Therefore using his clever inverse logic he used a much stronger salt solution over the entire image. This stabilised it, but as Gerald mentions it would still fade and change colour with time.

Alan Johnson · Oct 6, 2013

Gerald C Koch said:
Has anyone thought to test the film for residual silver? If not then the results are meaningless. An improperly fixed negative will eventually fade.

Yes, fair comment.
Attachment shows the fog levels with proprietary fixer, table salt fixer, and a strip fixed in table salt then redeveloped for 3x recommended time and washed only.
The darker color of the redeveloped strip suggests that the table salt strip was not quite completely fixed. Perhaps after years it would darken to the density of the redeveloped strip.

Gerald C Koch · Oct 6, 2013

It would be interesting to check the fixation with other films such as a fast film and a film which has a high iodide content such as T-grain or Delta films. These films are slow to fix with thiosulfate and should prove a challenge to a salt fixer.

Chris Livsey · Oct 6, 2013

I am more impressed that the emulsion was still on the base after 24 hours at 27 degrees and intermittent agitation.

Rudeofus · Oct 7, 2013

A-Shooter said:
The anti-caking agent in the table salt may give some fixing action depending on what agent is used. Some table salts contains small amounts of potassium or sodium thiocyanate. This is an express fixer agent. The amount in 150g salt used alone may fix he film in 10-15 minutes, but the salt really hampers the action.

If you look at these tables, you will see that Silver Chloride is quite soluble in Sodium Chloride, but that Ammonium Chloride works even better. Silver Bromide and Silver Iodide, of course, won't be easy to fix that way, but fortunately most common table salt contains Iodide which works as stabilizer. Likewise, the Thiocyanate you mentioned as anti caking agent will rather work as stabilizer, not as fixer.

If you have to fix film and just can't possibly get your hands on any trace of Thiosulfate, I would recommend multiple bathes of concentrated Ammonium Chloride at elevated temperature, with each fixing step no longer than 10 minutes. There is no need to wash between fixing steps in such a setup.

removed account4 · Oct 7, 2013

hi rudeofus

i have often thought of using salt if i can't get my hands on fix ...
once the film ( or print ? ) is soaked in salt and washed ...
when it is fixed in traditional fixer are there any worries of the image
film or paper being damaged by the fixer?

thanks!
john

Gerald C Koch · Oct 7, 2013

The amount of iodide in table salt is far too small to be of any use in fixing emulsions that contain silver iodide such as T-grain films.

Since a salt solution takes so very long to fix film it really is not a practical substitute for conventional fixers.

Rudeofus · Oct 7, 2013

jnanian said:
i have often thought of using salt if i can't get my hands on fix ...
once the film ( or print ? ) is soaked in salt and washed ...
when it is fixed in traditional fixer are there any worries of the image
film or paper being damaged by the fixer?

I don't think that table salt can damage your film, but please consider that Silver Iodide is VERY insoluble (by seven orders of magnitude less than Silver Chloride!), therefore I don't think you can properly fix a modern Silver Bromide Iodide emulsion with rock salt. Note, that the tables I linked to are for Silver Chloride, not the other Halides. You should be able to fix warm tone paper with rock salt, though.

Since inability to obtain Thiosulfate based fixer can only be a temporary issue in most parts of the world, you may want to look at stabilizer recipes which should keep your film stable until you get proper fixer. There are several recipes for stabilizer in Haist's book and probably elsewhere. Since stabilizers are quite dilute compared to fixer, keeping an emergency stash of their ingredients should require very little space and monetary effort.

Fixing in table salt solution

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