Fox Talbot and salt fixing ?

nmp · Oct 18, 2016

RalphLambrecht said:
....no matter how strong you'll make it hypo works much better.

The way I understand is both salt solution and the "pure" water treatments only remove the excess silver nitrate (necessary for to push forward the photo-chemical decomposition of the silver halide to obtain metallic silver) - the former by converting it to chloride and the latter by simply rinsing it out of the paper. It does not do anything to the unexposed silver halide. These procedures did stabilize the print to the extent that it could then be handled and shown around, which was a huge improvement. Only hypo is capable of actually dissolving the silver halide out of the print, a far better insurance for longevity, it would seem, than the other two treatments (as long as it too is thoroughly washed out eventually.)

pdeeh · Oct 18, 2016

RalphLambrecht said:
no matter how strong you'll make it hypo works much better.

That's quite correct Ralph, but there's nothing in my post nor in the subsequent discussions and contributions to suggest that thiosulfate is not superior to salt, and as the discussion is about what Talbot actually did, rather than what Lambrecht says works best, it is not clear what your contribution adds to the discussion?

pdeeh · Oct 18, 2016

nmp said:
Only hypo is capable of actually dissolving the silver halide out of the print, a far better insurance for longevity, it would seem, than the other two treatments (as long as it too is thoroughly washed out eventually.)

Well, maybe.

Some of the discussion and references quoted do suggest that it is possible that the other methods can provide good longevity for a salt print.

But until we have formal experimental evidence, we can't say for sure that they are either definitely inferior to hypo OR definitely as efficacious as hypo.

It's an interesting discussion, nevertheless.

nmp · Oct 18, 2016

pdeeh said:
Well, maybe.

Some of the discussion and references quoted do suggest that it is possible that the other methods can provide good longevity for a salt print.

But until we have formal experimental evidence, we can't say for sure that they are either definitely inferior to hypo OR definitely as efficacious as hypo.

It's an interesting discussion, nevertheless.

Understood. I am also aware that there is interest in what the salt fixing does to the color of the print. So if it does as good or good enough stabilization AND if it gives the sought-after tint, by all means it is a worthwhile effort.

nmp · Oct 18, 2016

Looks like Dr. Mike Ware has done the whole investigation about how vulnerable are the very first Talbot photogenic drawings that were fixed by salt solution. Very interesting read - answers a lot of questions:

http://www.mikeware.co.uk/mikeware/Photographs_Last.html

One of the concluding paragraphs:

"Having prepared, exposed, and chloride-stabilised some photogenic drawing paper according to Talbot's recipes, I took it to the Kodak Research Laboratories at Harrow, where I was welcomed by Hilary Graves, recently chairperson of the Imaging Science and Technology Group of the RPS and a recipient this year of the Society's Fenton Medal. With the aid of Hilary's colleagues, the paper was tested in one of Kodak's state-of-the-art densitometers, from which within minutes I was able to plot its rate of fogging. After making some corrections for high-intensity reciprocity failure, the TEL could be calculated: it came out again at about three hours. Bingo! A full house. All three independent paths of investigation had led to roughly the same conclusion. It was also easy to confirm the operation of the Becquerel effect in the chloride-fixed photogenic drawing paper by putting a yellow filter in the light path. The rate of fogging only dropped to half its previous value, which clearly demonstrated the sensitivity of this material to light of long wavelengths."

cliveh · Oct 18, 2016

Reading between the lines of Talbot’s notebooks (and this is just a personal opinion), you can see that even after he used sodium thiosulfate to fix some of his salt prints, he returned again and again to using a super saturated solution of salt. I feel sure his intent was to try and preserve the un-preservable. Namely the colours obtained immediately after exposure. Even using a super saturated solution of salt these colours change, but Hypo totally destroys them.

To make a photogenic drawing and observe it in the first few seconds before it changes, is the most beautiful form of imagery I have ever observed in a photographic process. I think his inability to arrest the un-arrestable, was probably his greatest regret. Even today, if you scan it in the dark or photograph it with flash photography, the resulting record does not compare with those few seconds of viewing the original and I think this was Talbot’s motivation to continue with so many experiments using salt.

But I could be wrong.

pdeeh · Oct 18, 2016

the blog page by schaaf ned linked to discusses precisely that point

cliveh · Oct 18, 2016

https://www.google.co.uk/search?q=s...hWFJ8AKHc3TDt0Q_AUIBigB#imgrc=lXhJvY_8tgfkPM:

NedL · Oct 18, 2016

I don't think you could be wrong Clive. Anybody who has opened a printing frame and looked at the delicate image inside will have felt the same. We grew up with photography all around us, it must have been even stronger for Talbot.

pdeeh · May 22, 2017

Just an addendum to this old thread.

I actually got around to making a couple of quick salt prints today, as I already had a frame setup after doing a few Namias sepias.

I'd got some acidified and salted but unsized paper lying about so I cut a couple of sheets and dabbed a bit of nitrate on.

After exposure, i stuck one straight under a running tap and left it there, for about half an hour while the other went straight into a strong salt solution with no intermediate wash.

After about 15 min the unwashed one had bleached somewhat and was brownish in colour.

The washed one was what I'd call violet but probably is what others call lavender. I dumped that into the salt solution too,whereupon it too bleached a bit but retained its pastel colour.

I'm not drawing any conclusions from this as its just me dicking about on a nice sunny day, but I thought I'd share it anyway.

Alan Johnson · May 23, 2017

In a different context I found that film emulsion was not completely fixed by salt solution in 24hrs.
Perhaps Fox Talbot did not test very long immersion times and his emulsion was only stabilized.
(there was a url link here which no longer exists)

pdeeh · May 23, 2017

Alan, this prompts me to realise that I don't really understand the processes whereby Sodium chloride solution can stabilise or even fix a salt print, or indeed any other Silver-based photographic material. I'm sure I must have read it somewhere but it's slipped away ...

The little I think I do know, I have gleaned from Mason and the Focal Encyclopaedia, and I have probably imperfectly understood them anyway.

Please comment and correct if necessary in what follows!

First, I think, in this context (chitchat about salted paper prints) at least, stabilisation and fixing are often used interchangeably, whereas for the photochemist, they are quite distinct processes.

(Further complicated by the fact that stabilisation has a quite different meaning in modern colour processing, where it is a process to protect the dyes and gelatin from deterioration; but as we're only talking about salted paper prints and other non-chromogenic processes I'll just leave that there).

Fixing is a process by which the undeveloped (or "un-printed-out"?) Silver halides are rendered into soluble compounds which dissolve out into the fixing solution, and the remnants of which are removed from the paper/gelatine/whatever in the subsequent washes.

Stabilisation is a process by which the Silver halides are rendered into insoluble but stable non-light-sensitive compounds, and no further washing takes place after stabilisation.

So, when we dunk an exposed salted paper print into a strong solution of Sodium chloride, what is actually happening to the remaining ("undeveloped" or "un-printed-out") Silver chloride? What complexes are formed, if any? Are they soluble, insoluble, stable, unstable, light-sensitive or what?

(Ware's article states that Silver chloride is left in the highlights of a salted paper print when stabilised with Sodium chloride solution, but he doesn't explain - there at least - what's happened to the rest of it)

As for experiments with "fixing" or "stabilising" modern materials with Sodium chloride solution, I wonder if the fact that they contain relatively little if any Silver chloride, with the bromide and iodide compounds being preferred, has any bearing? Or am I simply sniffing around at the bottom of a partially understood tree on my part?

(I love a smooshed-up metaphor.)

pdeeh · May 23, 2017

Aha just read your linked thread properly Alan and I note the following from Rudeofus (usually a reliable source of information):

Rudeofus said:
If you look at these tables, you will see that Silver Chloride is quite soluble in Sodium Chloride,

So perhaps we can infer that at least some actual fixation is taking place?

removed account4 · May 23, 2017

i think the fact that some of talbot's original work made using a salt bath
exists today, might prove that it does work?
i have a dark/sealed drawer FULL Of unstabalized/unfixed retina and sun prints.
... after a short period of time they turn completely grey..
would a washed, un -salt bath/un -fixed salt print fade the same way ? .... even in a dark drawer?

Alan Johnson · May 23, 2017

It may be possible to tell if there is any silver chloride left in a test print after first stabilizing in strong sodium chloride solution, then washing it.
If it is cut in half and one half placed in an ordinary film/paper developer, it would presumably get darker as the silver chloride is converted to silver.

Rudeofus · May 23, 2017

pdeeh said:
Aha just read your linked thread properly Alan and I note the following from Rudeofus (usually a reliable source of information):

So perhaps we can infer that at least some actual fixation is taking place?

Yes, this is actual fixation going on. The Chloride ion behaves a little bit like the Thiosulfate ion with regard to silver: the one to one salt (AgCl or NaAgS2O3) is quite insoluble, but there are water soluble higher order complexes ([AgCl2]-, [AgCl3]2-, [AgCl4]2-, just like [Ag(S2O3)2]3-, [Ag(S2O3)3]5-). I am quite sure you have read about the higher complexes of silver with Thiosulfate anion. The complex between Chloride anion and silver is much weaker than between silver and Thiosulfate anion, therefore you can't archivally fix Silver Bromide or Silver Iodide with Sodium Chloride. Silver Chloride, on the other side, is not all that insoluble, therefore Sodium Chloride can fix it.

If you look at the reaction AgCl + 3 Cl- <===> [AgCl4]3-, it becomes obvious that it will happen to greater extent if there are copious amounts of Cl- around. That's why concentrated Chloride solution is needed, see solubility data from the link.

Rudeofus · May 23, 2017

Alan, the easiest way to test for retained silver is whatever developer you may have lying around. Even if you are the most dedicated salt printer of the world, there's got to be an old bottle of HC-110 or Rodinal lying around somewhere ...

RalphLambrecht · May 23, 2017

pdeeh said:
Anyone who has read up a bit on the history of photography and on Fox Talbot's experiments with salt printing knows that to begin with, salted paper prints were fixed with a salt solution, until Herschel suggested the use of what we now call Sodium thiosulfate.

What I haven't found anywhere is any indication of what strength of salt solution FT was using for fixing - was it weaker than the solution used for salting the paper, the same, or stronger, or even saturated?

I expect the details are in his notebooks, but I can't find a digitised version online, and they're far too dear for me to purchase.

Can anyone shed any light (pun unintentional) ?

Afaik,he used the highest concentration he could make until told about hypo by Herschel

nmp · May 23, 2017

pdeeh said:
Aha just read your linked thread properly Alan and I note the following from Rudeofus (usually a reliable source of information):

So perhaps we can infer that at least some actual fixation is taking place?

Based on those tables in Salt Lake Metals, I did some quick calculations on what it would take, theoretically, to dissolve 1 gm of silver chloride in various solutions. See the attached table. The temperature vary slightly but for comparison purposes, they should be close enough. The last column shows how the others compare to 15% sodium thiosulfate (set at 1000) in terms of efficacy to dissolve AgCl.

10% Ammonia is actually better than hypo. The others are at least an order of magnitude less effective. Increasing the salt concentration towards saturation will obviously improve the solubility, so will higher temperature. However if I were to venture a conjecture, the kinetics of dissolving and carrying the silver chloride out of the paper will become a significant countering factor at higher concentrations.

So it would seem that, yes actual "fixing" can be done with sodium chloride in addition to just 'stabilizing" the silver nitrate. But how fast and how efficient is a question.

:Niranjan.

cliveh · May 23, 2017

nmp said:
So it would seem that, yes actual "fixing" can be done with sodium chloride in addition to just 'stabilizing" the silver nitrate. But how fast and how efficient is a question.:Niranjan.

If your interest is in how fast and efficient, I would suggest you have lost the plot about the aesthetic of photogenic drawings.

pdeeh · May 25, 2017

Rudeofus said:
Yes, this is actual fixation going on ... [snip]

One day perhaps I shall understand the bits I snipped

However, this is very interesting (well, I mean of course, it is interesting to me), because it seems to indicate that while many authors (and "authorities", viz Dr.Mike Ware) refer to Talbot "stabilising" his early prints in salt solutions, that he was actually fixing them, but fixing them incompletely. A photochemist would not call what has been done "stabilising" except perhaps as a loose or conversational term.

Lots of room left to experiment still though

Alan Johnson · May 26, 2017

I had a look for Fox Talbot's notebooks, which appear to be at the British Library and not easily accessed yet, I did not find anything relevant.
He seems to have been very busy and may not have tried fixing in salt solution for an extended time, to see if it both completely fixes the print and, as he wanted, preserves the lilac color.
Nor did I find any reports that anyone else tried fixing the prints for extended times, so at present afaik it has not been investigated.

cliveh · May 26, 2017

Perhaps one day Talbot's notebook L will be discovered and all will be revealed.

pdeeh · May 26, 2017

cliveh said:
Perhaps one day Talbot's notebook L will be discovered and all will be revealed.

Unfortunately, a large amount of the family's archives and correspondence was apparently lost in a house fire in Dorset in the early part of the 20thC
(I think at Abbotsbury, though Schaaf told me Melbury House - but Melbury House seems to be intact) and I suppose it is possible that his other notebooks were amongst them.

But, you never know. Maybe they'll turn up at a boot sale one day ...

removed account4 · May 26, 2017

unfortunately the family didn't have all his writings in a MOUND OF SALT ..
would have preserved them like cooking fish under a mound of salt .. they would have
been just right, not dried out or burnt especially if the house burned down and they were in indirect heat.

Fox Talbot and salt fixing ?

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