Fox Talbot and salt fixing ?

pdeeh · Oct 15, 2016

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) ?

TheToadMen · Oct 15, 2016

Maybe you could find an answer here? A historical site dedicated to Fox Talbot: http://foxtalbot.bodleian.ox.ac.uk
Or email it's curator: professor Larry Schaaf: larry.schaaf@bodleian.ox.ac.uk

removed account4 · Oct 15, 2016

pdeeh:

have you seen this ? its for his photogenic drawings.
https://jkschreiber.files.wordpress.com/2016/02/theartofphotogenicdrawing.pdf

it's a super saturated salt solution that is used to fix the prints.

i hope cliveh joins this thread because he has used this same method to make his own salt prints.

pdeeh · Oct 15, 2016

Bert, John -- thanks very much indeed for the links!

It had never occurred to me to contact Schaaf. who after all edited the notebooks for publication ... D'oh!

It seems (from the FT Museum data sheet hosted at the jkschreiber blog) that the fixing solution is "the stock salt solution diluted 50%".

As the stock solution is referred to as being made by "dissolving as much [salt] as possible in 300ml of hot water", and as a saturated solution of salt is about 36%, this gives us a fixer-strength solution of approx 18%

So ... question answered perhaps. It would be nice to see FT's original notes on the subject, the museum data sheet is mostly paraphrased.

One interesting thing is that it is noted that the salt fixation routine preserves (and even enhances) the lavender tones of a freshly exposed salted-paper print -- and Ned has commented in a few threads that that's something he'd like to preserve. I'll PM him a link I think.

NedL · Oct 15, 2016

I don't know what Fox Talbot did, but I've read about what some of his contemporaries and proteges did, and anecdotes about the habits of printers whose prints have lasted through the years. I think it is reasonable to think that salt prints can be permanently fixed with salt or with KBr, and that it all depends on how the prints are washed after fixing. But it's all conjecture...

EDIT: We were typing at the same time. Pdeeh, I didn't write about it much here, but I did finish experiments using sodium thiocyanate to fix salt prints -- it does work and it does not preserve the lavender color. Now you've pointed me in a new direction! My hunch is that any reasonably strong salt solution will work, as long as it is followed by a very long wash. I almost wish you hadn't discovered this little nugget, because the last thing I need is yet another direction to experiment with

pdeeh · Oct 15, 2016

I'm still worrying away at Namias, and what triggered this question was his mention of fixing sepiaprints with Sodium sulfite (giving a yellow image)
so of course I wondered what a sepiaprint would look like fixed in salt solution!

NedL · Oct 15, 2016

I'm signing off APUG now because I have to go coat some paper now. Cheers!

cliveh · Oct 15, 2016

I can throw some light on this, as he used a saturated solution of salt. Take a saucepan of water to the boil and dissolve as much salt as you can into the boiling water (loads of it). When cooled this is a super saturated salt solution and it is what he used to stabilise his photogenic drawings.

NedL · Oct 15, 2016

Very interesting reading; http://foxtalbot.bodleian.ox.ac.uk/to-fix-or-not-to-fix-sir-john-herschels-question/
Hershel's 177 year old photogram of leaves is lovely.

pdeeh · Oct 15, 2016

cliveh said:
I can throw some light on this, as he used a saturated solution of salt. Take a saucepan of water to the boil and dissolve as much salt as you can into the boiling water (loads of it). When cooled this is a super saturated salt solution and it is what he used to stabilise his photogenic drawings.

Ok, thank you Clive -- and that's chapter-and-verse from the notebooks ? (I seem to remember you own them)

If so, I wonder why the FT Museum data sheet suggests diluting the saturated solution to 50%?

So far as I can ascertain, by the by, the solubility of salt in water doesn't increase significantly with increasing temperature of the water - according to the Blessed Wikipedia, 36g/100ml at 20C going up to only ~39g/100ml at 100C.

pdeeh · Oct 15, 2016

NedL said:
Very interesting reading; http://foxtalbot.bodleian.ox.ac.uk/to-fix-or-not-to-fix-sir-john-herschels-question/
Hershel's 177 year old photogram of leaves is lovely.

Now that is very interesting article!
I wonder if it were possible to get a ready supply of ultrapure (google that) water, one could do away with a fixing agent altogether?

pdeeh · Oct 15, 2016

I love this quote:

William Henry said:
several persons of taste having been consulted on the point, viz. which tint on the whole deserved a preference, it was found that their opinions offered nothing approaching to unanimity, and therefore, as the process presents us spontaneously with a variety of shades of colour, it was thought best to admit whichever appeared pleasing to the eye, without aiming at an uniformity which is hardly obtainable.

Reminds me of Emerson (Ralph Waldo, not Keith): A foolish consistency is the hobgoblin of little minds

cliveh · Oct 15, 2016

pdeeh said:
Ok, thank you Clive -- and that's chapter-and-verse from the notebooks ? (I seem to remember you own them)

If so, I wonder why the FT Museum data sheet suggests diluting the saturated solution to 50%?

So far as I can ascertain, by the by, the solubility of salt in water doesn't increase significantly with increasing temperature of the water - according to the Blessed Wikipedia, 36g/100ml at 20C going up to only ~39g/100ml at 100C.

I don't own them, but I have read the original notebooks stored in the Bradford museum. The 50% you mention is in fact about 20% for sensitisation and not for stabilisation.

removed account4 · Oct 15, 2016

hi clive

the 50% for fixing and 1:18 parts of water for sensitizing is from the pamphlet from
the talbot museum, i posted a link to it previously in this thread.
https://jkschreiber.files.wordpress.com/2016/02/theartofphotogenicdrawing.pdf
maybe the dilutions are different between salted paper prints and photogenic drawings ?
the pamphlet talks about talbot's photogenic drawings .. unless they are the same thing?

pdeeh · Oct 15, 2016

cliveh said:
I don't own them, but I have read the original notebooks stored in the Bradford museum. The 50% you mention is in fact about 20% for sensitisation and not for stabilisation.

Let us be clear: Had you read the post of mine you actually quote, you would note that I am quoting the data sheet from the FT Museum linked by john's post above. You can find it here, for reference:

https://jkschreiber.files.wordpress.com/2016/02/theartofphotogenicdrawing.pdf

The relevant parts can be found on pages 6 & 7.

On page 6 you will find the following:

Take a stock solution of salt by dissolving as much as possible in 300ml of hot water ... for use in preparing the paper, dilute 1 part stock solution with 18 parts water

That equates of course to the normal 2% we normally use for salting paper.

On page 7 you will find the following:

Fixing the image ... immerse it in a strong solution of salt for a few minutes [use the stock salt solution diluted 50%]

Furthermore, CLive, please don't post obscene personal attacks on me which have to be edited by the moderators to remove. I doubt you'll have the grace to apologise to me, but your attitude leaves something to be desired to say the least.

cliveh · Oct 16, 2016

pdeeh, I do apologise if I have offended you, this was not my intention.

Tom Taylor · Oct 17, 2016

I'd get close to, but not at, the saturation point @ 20C:

The saturation level is dependent on the temperature of the water. At 20 °C one milliliter of water can dissolve about 0.357 grams of salt; a concentration of 26.3%. At boiling (100 °C) the amount that can be dissolved in one milliliter of waterincreases to about 0.391 grams or 28.1% saline solution.

Thomas

pdeeh · Oct 17, 2016

TheToadMen said:
Maybe you could ... email... professor Larry Schaaf: larry.schaaf@bodleian.ox.ac.uk

Well, it turns out that Professor Schaaf (I call him Larry) is a friendly soul who takes the trouble to answer impudent email queries from total strangers, and on Sunday evenings to boot ... this is what he had to say:

Larry Schaaf said:
Chemical terminology – and indeed chemical strength and purity – was much less precise in Talbot’s day. We can be pretty sure that he did not use trendy Himalayan Pink Salt for his experiments but rather whatever he found in the kitchen of Lacock Abbey. His references are to a ‘strong solution’ and often to a ‘saturated solution’ of salt for fixing. Presumably this was at room temperature, itself a variable, but should give you some guideline ... That is all rather vague but do not hesitate to ask additional questions

So we still don't know for sure what the solution strength was that Talbot used, but at least we know -- from an authoritative source -- that he didn't document it precisely himself in any extant notes.

Back to experimenting everybody ...

TheToadMen · Oct 17, 2016

pdeeh said:
Well, it turns out that Professor Schaaf (I call him Larry) is a friendly soul who takes the trouble to answer impudent email queries from total strangers, and on Sunday evenings to boot ...

And he writes a nice blog too: http://foxtalbot.bodleian.ox.ac.uk/blog/

pdeeh · Oct 17, 2016

Tom Taylor said:
I'd get close to, but not at, the saturation point @ 20C:

The saturation level is dependent on the temperature of the water. At 20 °C one milliliter of water can dissolve about 0.357 grams of salt; a concentration of 26.3%. At boiling (100 °C) the amount that can be dissolved in one milliliter of waterincreases to about 0.391 grams or 28.1% saline solution.

Thomas

I think I understand the distinction you are making ...

When I made my remark about saturated solutions, I was thinking about it as we normally do when making up (e.g.) a developer - adding a fixed amount of substance to an amount of water, allowing it to dissolve fully, then topping it up to the final solution volume to give the desired dilution. We normally do this w/v.

That got in the way of my recognising that taking a volume of water and adding salt to it until one can dissolve no more is rather different, and of course the solution volume will increase as more and more salt is added, hence the solution values you give.

Have I understood your (slightly terse ) post correctly ?

cliveh · Oct 17, 2016

pdeeh said:
Well, it turns out that Professor Schaaf (I call him Larry) is a friendly soul who takes the trouble to answer impudent email queries from total strangers, and on Sunday evenings to boot ... this is what he had to say:

So we still don't know for sure what the solution strength was that Talbot used, but at least we know -- from an authoritative source -- that he didn't document it precisely himself in any extant notes.

Back to experimenting everybody ...

I would suggest from my own experiments that just like Larry mentions, Talbot's experiments were far from precise in both formulation and chemical composition.

You will still get an image from a variety of sensitisation formula as you will get stabilisation from a variety of salt solution strengths. However, (and I may be wrong here) I believe that a certain strength of sensitisation (by this I mean the ratio of salt to silver nitrate) coupled with a certain strength of salt stabilisation solution, is capable of producing a very stable image indeed. I once did a series of experiments where I kept the stabilisation concentration fixed (super saturated salt solution), but varied the sensitisation formulation by reducing the silver nitrate concentration in distilled water over a series of measured dilutions. I am a poor note keeper and can’t report the precise AgNo3 concentration (how convenient you may say, but I do not talk bullshit), but I was able to produce one salt print that did not alter or fade when left in direct sunlight (I didn’t like the aesthetic effect of the particular image in question and didn’t keep it).

In Talbot’s note books P & Q he alludes to a similar discovery.

NedL · Oct 17, 2016

Hi Clive and all,

I don't doubt this in the least. It makes perfect sense that the salt to AgNO3 ratio would matter. Another factor might be the subject or negative. Many examples of photogenic drawings have a dark background, and many salt printers seem to gravitate toward dark backgrounds and borders instead of more high key prints. In these darker prints, more of the AgCL will be converted to silver. And since we think the free CL recombines with the excess silver nitrate during exposure, if there is little enough excess there could be areas where the silver is mostly exhausted, leaving little AgCL needing to be stabilized.

I also don't doubt the "pure water" fixing in that description of what Hershel did. 0.002 g/L makes it sound like AgCL is very insoluble, but if you sit down and figure out how much silver chloride might be left on a print, or especially a photogenic drawing, it doesn't seem unreasonable at all that a long wash could remove most of it. This isn't like those "fixing film with salt" threads...

Your signature quotes the greatest empiricist, and we should always see for ourselves. My experiment yesterday failed for unrelated reasons, but I made up some 20% salt solution, and will give that a try and see what happens... to be honest I'm mostly curious about what happens to the colors of the print...

Clive: do you remember if you washed the prints before putting them in the strong salt solution? Or did they go straight in?

Tom Taylor · Oct 17, 2016

From what I have read, both Talbot and Daguerre fixed their prints with a "strong salt solution." I believe that Talbot used ordinary table salt (sodium chloride) for his salt prints and I imagine he also used a "strong" solution of sodium chloride for fix which was no doubt carried out at "room temp" or 20C. To me a "strong" solution would be close to the saturation level at 20C. More salt would have left granular salt particles in the fix and on the print.

Thomas

cliveh · Oct 18, 2016

NedL said:
Clive: do you remember if you washed the prints before putting them in the strong salt solution? Or did they go straight in?

No wash after exposure, just poured super saturated salt solution over the print.

RalphLambrecht · Oct 18, 2016

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) ?

all Iread is that is was a very strong salt solution but ,I have no further details and no matter how strong you'll make it hypo works much better.

Fox Talbot and salt fixing ?

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