How much Silver is in a sheet of FB Paper?

Discussion in 'B&W: Film, Paper, Chemistry' started by Martin Aislabie, Apr 22, 2009.

  1. Martin Aislabie

    Martin Aislabie Subscriber

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    I have been doing a bit of experimenting with toning of Ilford MGFB in Gold Toner :D

    On the Silverprint Web Site, Martin Reed mentions that a 1L bottle of Gold Toner only contains aprox 0.5g of Gold - which does not sound like much- http://www.silverprint.co.uk/ProductByGroup.asp?PrGrp=542

    But then, I started to wonder how much Silver is in a single sheet of 10x8 MGFB paper - for comparative purposes to the 0.5G of Gold in the Toner :confused:

    Thanks

    Martin
     
  2. Marco B

    Marco B Member

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  3. Photo Engineer

    Photo Engineer Subscriber

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    Paper is usually reported in mg/square meter or mg/square foot.

    In my experience, papers run from about 125 mg / square foot to 250 mg / square foot. This agrees reasonably well with the table in Marko's reference. This relates more to a contrast issue than a Dmax issue though, as you can coat quite a range of silver halide and are still limited to a dmax of 2.2 roughly for gloss and about 1.9 for matte paper surfaces, just by the laws of physics.

    I pretty much said that in the other thread. Silver Rich is a myth invented by those that could not get the right contrast except by loading a paper with silver halide to jack up contrast. They had poor emulsions and compensated quantity for quality in a sense.

    PE
     
  4. Marco B

    Marco B Member

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    PE, why do you keep consistently writing my name with a "K" instead of "C"... :confused:

    Time for a new pair of glasses maybe? :wink:

    Marco
     
  5. Marco B

    Marco B Member

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    And now another interesting question is how much gold replaces silver in an 8x10 sheet when toning? E.g. 80 mg silver = 80 mg of gold or NOT???

    Probably we need to do some molarity based chemistry calculation, but does someone have the figures ready?
     
  6. Photo Engineer

    Photo Engineer Subscriber

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    Marco;

    Apologies to you for my error. I hope no one ever does it again, myself included.

    PE
     
  7. Marco B

    Marco B Member

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    Apologies accepted :wink:. It wasn't a big deal at all, but I have seen you writing my name with K in a few other threads as well, so I started wondering :surprised::D. Actually, there are Marco's with K in the Netherlands, but C is more common.

    I also started to wonder what substance of gold is created during gold toning. If you want to make a molarity based calculation, assuming all metallic silver is replaced by gold, it will make a difference to the total weight of the final deposit if the gold is not pure gold, but some compound bound with another substance, like for example a sepia toned image where the silver binds with sulphur. Of course, the amount of gold used per sheet is not influenced by that, because that is purely based on the molarity calculation and the ratio of number of silver atoms replaced (or is it supplemented?) by number of gold atoms.

    Does gold toning replace silver, or deposit as a layer on the silver?
     
    Last edited by a moderator: Apr 22, 2009
  8. Kirk Keyes

    Kirk Keyes Member

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    Both, I thought. It's a "noble" metal replacement reaction - the gold plates onto the silve as a thin layer on top, but an equal molar amount of silver is lost to solution. Also, there's thiocyanate in the gold toner, I'm assuming it's acting as a silver solvent to etch/clean the surface of the silver.
     
  9. Photo Engineer

    Photo Engineer Subscriber

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    I had always thought that some sulfides formed during Gold toning. Any ideas on that Kirk?

    PE
     
  10. dancqu

    dancqu Member

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    That's about it, 0.08 grams per 8x10 or 1.6 grams per
    square meter. That's an average of several papers. Slavich
    claims the least at 1.2 - 1.3 while I've seen another at 2.2
    grams per square meter.

    The specific mix of halides will make a difference when it
    comes to fixing. As expected, after testing 4 papers, Slavich
    takes the least and Kentmere Bromide the most; at least
    half again more.

    If you want warm tones at nearly no per print expense then
    Nelson's Gold Toner is the one to use. As I understand it,
    Nelson's is essentionally a sulfide toner modified in
    color by the the gold's presence. Great for
    archival results. Dan
     
  11. Marco B

    Marco B Member

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    Of course, there is another aspect we are forgetting. Assuming an average photo is "18% grey", and that that also translates in 18% silver left after fixing, the amount of silver of an 8x10 sheet might be somewhere in between about 15-40 mg...

    That would mean that the 0.5 g gold could go a very long way in toning 8x10s, if we also take in account that only a small portion of the silver is replaced by the gold based on Kirk's response. If we again, and this is completely guess work!, just for the sake of getting a feel, assume it's 20% percent replaced, than only 3-8 mg of silver needs to be replaced for a single sheet.

    If 3-8 mg of silver translates (and this is another blatant assumption!) in 3-8 mg of gold, than 500 mg gold toner might tone anywhere between 60-160 sheets (just a rough calculation)

    Marco
     
  12. Ray Rogers

    Ray Rogers Member

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    I think that is what the link you posted was getting at, that capacity depends on print density...

    Many people like low key-
    I don't - but...
    as PE has mentioned, D-max is not strictly related to silver content.

    In any case,
    Tetenal's claims their toner should tone about 13 8x10's per liter.
    depending upon yes, how black the image is;

    High Key will give you more prints per Euro.

    How many prints you can do also depends on how other factors.
     
  13. Martin Aislabie

    Martin Aislabie Subscriber

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    I was trying to find out how much Silver was coated on a piece of virgin photographic paper.

    You have taken it through the next two steps of my thought process :D

    I am toning for the cold tones achievable with Gold.

    If the print has first been Selenium Toned - to the level where colour change is see in the high tones - what is the chemical action of the Gold Toner?

    This must also affect the Gold Toner baths life (for a given print density)

    Also, I don't know if it is significant but - Gold Toner is missing from both the Tetenal & Fotospeed Web Sites :sad:

    Martin
     
  14. L.J.SILVER

    L.J.SILVER Member

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    Do excuse the naive question please but why does gold toning give a bluish tint instead of a 'golden' tint?
     
  15. Marco B

    Marco B Member

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    Maybe not much at all. If you have a clearly visible shift in tones, much of the available silver may already have reacted with the selenium. In general, I think it's more difficult to control or judge the extend to which selenium toning has taken place, than for example a bleach/tone toner like a thiourea based sepia toner.

    But of course Tim Rudman is the expert, maybe he can tell you something about split selenium and gold toning.

    In general, the color of any substance is determined by it's spectral reflectivity. If the reflected light happens to be mainly "blue-ish", as with the substances and complexes created by gold toning, it will look blue.
     
  16. Ray Rogers

    Ray Rogers Member

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    This question is quite interesting and much could be written about it.
    Why indeed is silver black?
    Not long ago, it was debated and ideas put forth that the strands trapped the light... but what color are silver filaments that have been grown to vulgar sizes?!!

    Why are diamonds colorless, (some of them are blue) but graphite grey black and what are the different methods of color synthesis anyway? I asked S.G. to respond to this, because he seems to be the most fluent in this area, but I guess I asked too much... another understatement.

    But the very poorly answered basic question is that the image particle size and shape, (plus x,y and z), change the way we percieve the image's color.

    Buy why and how?

    What is "color" anyway?
     
  17. Photo Engineer

    Photo Engineer Subscriber

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    Silver is not "black" in any form. It has some degree of color whether brown or blue. It can also be bright yellow, bright green and etc... Cary Lea Silver is bright yellow and very dense in absorption per unit of silver metal. About 10 mg/sq ft will give a density of 3.0.

    There is no simple rule on color and that is why silver metal step wedges are not used for critical sensitometric purposes. I discussed this in a previous post.

    PE
     
  18. Kirk Keyes

    Kirk Keyes Member

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    Oh man - there's whole books written on that subject!
     
  19. Ray Rogers

    Ray Rogers Member

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    Thats why we call it "Black and White Photography"!

    :D
     
  20. dancqu

    dancqu Member

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    Black image silver. It appears black because it
    absorbs all wave lengths of our visual spectrum.
    To know why it does that takes one into a study
    of the physics of light and the electromagnetic
    spectrum and their interaction with materials.

    A notable example is Global Warming. Carbon
    dioxide is unaffected by incoming wave lengths
    of the spectrum but absorbs out going heat wave
    lengths of the spectrum. So, the more CO2 the
    less out going energy. The greenhouse effect.
    BIG GREENHOUSE.

    The perception of color, as I understand it, is
    the result of eons of evolution. Not all seeing
    animals perceive color. Dan
     
  21. Photo Engineer

    Photo Engineer Subscriber

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    Well Dan, I'll have to respecfully qubble with your answer. Having seen the spectrophotometric curves of several types of silver, I can say that they vary and none of them absorb between 400 and 700 nm (the human visual range) in a linear fashion, but rather have tilts or humps in their absorption spectra to reflect blue, gree and warm tone images which we have all seen.

    On a single stimulus basis with only one sample in front of us, or under a particular illuminant, a given silver may appear black, but to the discriminating eye or a spectrophotometer it is not.

    PE
     
  22. Kirk Keyes

    Kirk Keyes Member

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    WHAT?

    Carbon dioxide can absorb IR (heat) radiation coming in as well as going out.

    It absorbs the energy, which causes the CO2 molecule to vibrate at a higher rate that before it aborbed the radiation. It can release the radiation which can then be aborbed by another CO2 molecule, thereby "trapping" the heat. The more CO2, the more heat is retained by the atmosphere.

    But it can do this for radiation that coming from the sun, released by another molecule in the atmosephere, or reflected or released from the surface of the earth.
     
  23. Marco B

    Marco B Member

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    I think dancqu meant that the IR heat radiation waves are primarily of "earth" origin, as the earth absorbs the sunlight (full light spectrum) and transmits it partially back into space at longer wavelenghts.