Lo and Behold: Turns out Black Salt Makes a Terrific Toner

Discussion in 'Alternative Processes' started by nmp, Jul 10, 2017.

  1. nmp

    nmp Member

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    (or this one weird trick....)

    I didn't know where best to post this. But since I fell into this “discovery” (didn't find any instances in literature, do point out otherwise) while working on my salt print process, this forum might be as good as any. It seems that the Himalayan Black (or Pink) Salt (you would know it if you know South Asian cuisine well as I do) can act as a pretty good (?) toner for silver prints.

    Recently I decided to experiment with Polysulfide (Kodak Brown Toner or T-8 type) toning to see for myself if anything good happens with salt prints. Both selenium and sulfide toning are not as popular with salt printers as various gold/platinum/palladium based toners, due to their propensity to severely bleach the images. In any case, I acquired some liver of sulfur for that purpose and soon as I opened the bottle, the smell reminded me (among other things) of the black salt. For those who don't know, Black salt or Kala Namak (literal translation in Hindi)

    (https://en.wikipedia.org/wiki/Kala_namak)

    is a natural salt mined along the Himalayas. It contains loads of minerals as well as many sulfurous compounds including sulfides, sulfites etc. Turns out I had a some in my spice cabinet so I thought let's see what would happen if I make a solution and tested it for toning.

    I took a few test strips of salt print (ironically, salt-free salt print - details of which I will present in another thread at some point) all fixed and washed and dunked them in various concentrations of black salt 0.2% to 5% in plain water (no other additives) for 10 minutes each.

    Attached files summarize the results. Each strip contained two zones for 40 minutes and 5 minutes each of UV box exposure – signifying 3 stops of difference. Toning (which I define as increase in density and/or change in color towards more neutral) was achieved to varying degree accompanied by bleaching (loss of density) as well, particularly in the lighter step. As the black salt concentration went up, the tone changed towards more neutral from the reddish brown/yellow hues of the control un-toned sample. That was evident even at lowest 0.2% concentration. The darker 40 minutes step intensified in all cases except the 5% one. In the lighter zoneS, there was bleaching at all concentrations, worst being at the highest. In essence, if one considers the delta between the 40 min and 5 min exposureS (Column 4 in the spread sheet) as some sort of contrast measure, it improves with toner concentration, a fact that can be used in one's favor if using lower contrast negatives.

    Conclusion:

    I might have stumbled upon yet another way to tone the salted prints using the Himalayan black salt. Granted this is not a very well defined as a chemical and the efficacy will vary depending on where it comes from, but it is very cheap and edible to the boot. Nowadays it is available practically everywhere - even Walmart sells it. It does give off smell but in a well ventilated area, there should be no problem.

    More optimizing needs to be done. The 0.2-1% toner concentration look the most promising in terms of maximizing the color shift with modest Dmax boost and least bleaching at lower density. More time dependent experiments will help. Perhaps addition of an alkali like sodium carbonate may influence the bleaching behavior as well.

    Much to do....

    Feel free to try out yourselves!

    :Niranjan.
     

    Attached Files:

    Last edited: Jul 10, 2017
  2. Peter Schrager

    Peter Schrager Subscriber

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    thank you Niranjan for this information...do you have prints to show??
    Best, Peter
     
  3. TheToadMen

    TheToadMen Member

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    Interesting experiment. Results look promising. I'll keep an eye out for your progress.
    Thanks for sharing!
    Bert from Holland
     
  4. OP
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    nmp

    nmp Member

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    Thanks guys. I am still working on the individual building blocks. I hope I will be able to put all of them together soon and have an image or two to share. Proof is in the pudding, as they say.

    Also working on Selenium toning and the results are very similar so far to those here.
     
  5. ced

    ced Member

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    Hello Niranjan! Have you tried this salt as a 1st coating before the silver, without toning?
     
  6. OP
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    nmp

    nmp Member

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    That's a very good question, ced. It is after all about 95% NaCl so it should function as "the salt" if applied before silver. The question is what do the "toning" compounds do in the mean time to the silver nitrate and the silver chloride that is formed in the paper. If they do not react before exposure (which would be my suspicion,) will they function as an in-situ toner afterwards. Kind of 2-fer if it does. Should be easy enough to find out. I will do the experiment and report back...

    :Niranjan.
     
  7. Steve Smith

    Steve Smith Member

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    Is this different to the pink Himalayan salt? Other than colour!!


    Steve.
     
  8. OP
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    nmp

    nmp Member

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    They are both identical. It is actually pinkish in color in the powdered form. The "black" name probably comes from the darker color of the chunk form that was traditionally available (or may be because it was simply "not white").
     
  9. ced

    ced Member

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    Niranjan look forward to your result on this test.
     
  10. BrianShaw

    BrianShaw Member

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    Are you sure. I use both salts and they sure look, taste and smell different. Pink Himalaya is salty. Pink salt is pink in color. Black salt (that I use) is black in color - both as chunks and powdered). Black salt is salty but more sulfurous than any other salt I've ever used. Almost sewage smelling. But necessary and good in Bengali (and probably other) cooking.

    But no matter... this is a fascinating investigation and I'm very interested in following your progress.
     
    Last edited: Jul 20, 2017
  11. Anon Ymous

    Anon Ymous Member

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    If it contains any sulfides, then it will simply create fog, in the form of silver sulfide. That would make it unsuitable.
     
  12. OP
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    nmp

    nmp Member

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    Now that you ask me, I am not so sure. I was not aware of the it being called "pink" until I started to read a little after my experiments. Growing up in India, we always knew it as Kala Namak. There is probably some processing involved after the mining that imparts a darker color to make the Kala Namak. Even wiki has two pages -one for Himalayan salt and the other for Kala Namak.

    Mine looks just like this (same brand):

    https://www.walmart.com/ip/Deep-Bla...5035&wl11=online&wl12=172551964&wl13=&veh=sem

    except mine says "Rock Salt" instead of "Black Salt." Looks like this needs more research to get to the bottom of it.
     
    Last edited: Jul 20, 2017
  13. BrianShaw

    BrianShaw Member

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    The salt in the link looks just like the black salt I use. I should been more accurate and said that mine was very dark when in chunks and the ground version is more brown... as depicted. The smell is the real indicator! I get mine in an Indian Sweet and Spice shop and have no idea what the label says since I can't read it.

    There are other black salts that I'm aware of but I have no experience with them: Cyprus black salt, Hawaiian black salt, and a slew of smoked salts that are brownish in color.

    I think the only relationship between Himalayan Pink Salt and Kala Namak is that they may be mined from the same range of mountains. But given the Wikipedia description of how it is synthetically manufactured who knows what we've been cooking with. :smile:
     
    Last edited: Jul 20, 2017
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  15. OP
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    nmp

    nmp Member

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    This is from: http://www.onegreenplanet.org/vegan-food/everything-you-need-to-about-black-salt/

    "Indian black salt, or kala namak, is an Indian volcanic rock salt. It is known by many names including Himalayan black salt, sulemani namak, and kala loon. It is commonly used in Pakistan, India and other Asian countries. It starts out as Himalayan Pink Salt or sodium chloride and is then heated to extremely high temperatures and mixed with Indian spices and herbs including the seeds of the harad fruit which contains sulfur. It also contains trace impurities of sulfates, sulfides, iron and magnesium which all contribute to the salt’s color, smell and taste."

    There is also a description of "black salts" from other parts of the world.

    When I dissolve it in water, the solution is greenish at first with a quick whiff of the sulfur smell. There are a few dark specs that do not dissolve and hang around. After a day or so the solution becomes colorless.

    Plot thickens....
     
  16. BrianShaw

    BrianShaw Member

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    absolutely fascinating!
     
  17. OP
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    nmp

    nmp Member

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    Yep. I put a drop of AgNO3 solution in a solution of black salt and sure enough it immediately gave black/gray precipitate implying a stain/fog would result if used as the salt in salt print. Expected it, but always good to check if you can.

    Attached:

    1. Greenish solution of black salt in daylight
    2. Same under safelight
    3. After a couple of drops of AgNO3 solution is added in safelight
    4. Same as 3 in daylight taken immediately

    If it was pure sodium chloride, the result would have been white liquid which would slowly turn darker in daylight.
     

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  18. NedL

    NedL Subscriber

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    I just discovered this thread, sorry I missed it before! I've tried a few different salts for the salt ingredient in salted paper prints... just looked in the cupboard and one was "Kala Namak Black Sea Salt". It made a grey fog upon coating the AgNO3, just as Niranjan predicted. I never learned much about this particular salt, and thought maybe it was sea salt from the Black Sea :smile: Sounds like mine might have been mislabeled ( I've noticed sometimes in US stores, all "exotic" salts are called "sea salt" even if they come from mining ). A few months ago, my daughter came and asked me "Can salt go bad?" She said "That salt you bought has gone bad or something is wrong with it!". It does have an unpleasant sulfurous odor.
     
  19. OP
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    nmp

    nmp Member

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    As long as it smells bad, it has not gone bad...:smile:
     
    Last edited: Nov 20, 2017
  20. jnanian

    jnanian Advertiser Advertiser

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    you have mde my day !
    thanks :smile:
     
  21. NedL

    NedL Subscriber

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    Smells a bit like hard boiled eggs when you dissolve it in water. Tonight I stuck a strip of undeveloped unexposed photopaper in some and sure enough it made a tone almost immediately, got a little darker after a few minutes but didn't do much more. So, like sulfide and thiocarbamide toners, it tones silver bromide regardless of whether it's exposed or developed. It ended up about a medium tan color... will try adding some alkali next time, or anything else anyone wants to suggest!
     
  22. OP
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    nmp

    nmp Member

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    Thanks Ned. Looking forward to see how this works on the traditional bromide papers.

    :Niranjan.
     
  23. Daniel Eriksen

    Daniel Eriksen Member

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    Not sure if this is the right place to ask this, but here goes.
    Does anyone know if there is any way to make a salt print without sepia tone or if there is any way to remove the tone, so the print is "pure" black and white?
     
  24. NedL

    NedL Subscriber

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    Welcome to Photrio! There are a number of toners that work with salted paper... some are quite neutral. This thesis has some examples.
     
  25. OP
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    nmp

    nmp Member

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    Not sure about "pure" black and white, but most additive toning processes will move the image to more neutral tones, presumably by increasing the grain size from sub-micron to micron levels. The downside is most of them will bleach the image as well, as evident in the figures on the post #1 here. So one can not tone to the maximum to get pure black and white. Noble metal toning may behave somewhat different from the likes of selenium or sulfur based toners (basis of my experience.) But how close they are to black and white is a good question.

    I have wondered before what would happen if you bleach/brominate the image and redevelop using a standard developer, would the outcome be more akin to a traditional bromide paper. Something to try, may be.

    :Niranjan.
     
  26. NedL

    NedL Subscriber

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