URGENT HELP! SALT PRINTING -contamination/fogging?

Discussion in 'Alternative Processes' started by JOHN McMURTRIE, Feb 8, 2018.

  1. JOHN McMURTRIE

    JOHN McMURTRIE Member

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    Need some help with a contamination/fogging issue I am having with a print. It is a salt print. Everything is fine up to the fix and wash stage. I am getting a grey contamination on the paper. I suspect it is not enough washing before the fix as it looks like the Silver Chloride fogging as I wash them out in daylight. Any advise or suggestions would be very helpful. Thanks

    IMG_1028 low res.jpg
     
  2. nmp

    nmp Member

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    Hi, John: If I were to make a first guess, I would think it has something to do with the sensitizer seeping into the paper. If you look in the back of the paper, do you see corresponding stains, perhaps slightly darker and more brown?

    :Niranjan.
     
  3. OP
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    JOHN McMURTRIE

    JOHN McMURTRIE Member

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    Yes identical staining on the back. I think I was a bit too generous when I sensitised the paper. Originally I used a syringe but that got contaminated so I pool a puddle in the middle of the paper and paint it out. That said, the fixer should kill it from going dark so could it be my wash bath out in daylight exposing it. Therefore not enough fix?
     
  4. nmp

    nmp Member

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    I have similar issues if I use too much sensitizer or I allow it to linger too long out before putting it in the dryer. Check the lower part of the white border and the step-wedge area in the photo in this link.

    https://www.photrio.com/forum/threads/salt-free-salt-print-toned-with-himalayan-black-salt.155417/

    There are similar irregular stains, although I assumed they formed during exposure so the under-fixing would have had no effect.

    Yeah, I would try using longer or stronger fix (I use 15%) and see what happens. Or may be use 2 fixing trays, the second one with fresh fixer. If the fixer can not reach down into the paper to get all the silver halide, subsequent washing in the daylight would form the stains. If the fixer does reach in and complexes with the silver halide, but if the washing does not remove those complexes completely, stains could develop in the drying phase as well.

    Alternatively, probably best to work on ways to improve the coating by using less of it or sizing the paper (assuming you are not already doing it.)

    :Niranjan.

    Addendum:
    By the way, are you using a salt rinse step before fixing? If you have any stray silver nitrate in the paper, fixer will react with it to form insoluble silver compound that could also be a potential source of stains (incidentally this reaction is the basis for checking residual fixer in the paper.)
     
    Last edited: Feb 9, 2018
  5. Wayne

    Wayne Subscriber

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    Why is it necessary to scream? Why is this URGENT?
     
  6. OP
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    JOHN McMURTRIE

    JOHN McMURTRIE Member

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    1. If you don't have anything useful to say, why get involved with such an irrelevant comment.
    2. A bit rich coming from an American
    3. Because it is a print for the Royal Academy Summer Exhibition. Deadline is Monday.
    4. IS THAT OK WITH YOU?
     
    Last edited: Feb 9, 2018
  7. OP
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    JOHN McMURTRIE

    JOHN McMURTRIE Member

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    Thanks!

    Yes the paper is sized with 2g of Gelatine to 20ml. The problem I have now is lack of good blacks. All my previous Salt prints have had excellent contrast, just brilliant blacks, but this latest batch of 6 prints are so flat! I think it must be the weather, unless you can think of anything? Cloud normally produces better results but not the last couple of days.
     
  8. NedL

    NedL Subscriber

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    Is the salt mixed with the 10% gelatin or are you using a separate sizing step first? What kind of paper is this?
     
  9. Ces1um

    Ces1um Subscriber

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    @JOHN McMURTRIE I've no idea about anything that has to do with salt prints, but I had to say- very cool photo.
     
  10. Prof_Pixel

    Prof_Pixel Member

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    Did you by any chance change the paper you are using?
     
  11. OP
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    JOHN McMURTRIE

    JOHN McMURTRIE Member

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    The paper is Platinum Rag and the 2g Sodium Chloride is mixed with 10ml of distilled and added to 20ml of 70'c distilled water with 1g Gelatine dissolved. Tried and tested and usually all good. I think the outside temperature and the light is particularly poor right now in the UK, hence getting such flat results. I just need to be a bit more controlled with my sensitising. I literally poured it on the paper last night and brushed it in with a foam brush. The sensitiser dried in patches.
     
  12. NedL

    NedL Subscriber

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    I'm thinking about the staining and also the veiling fog that is all around and within the image... before, you wrote 2g gelatin in 20ml water which would be 10%. 1g gelatin in 20ml water is 5%. 2g salt in 10ml is too much, I don't think it would print... do you mean 0.2g?

    The reason I'm asking is that thick gelatin can cause various kinds of problems, especially if it's not evenly coated all over the surface of the paper ( e.g. by floating rather than brushing on ). If the sensitizer seeps in underneath the gelatin, it can 1) form light sensitive compounds with the paper's internal sizing 2) be very difficult to wash out 3) be difficult to fix 4) be difficult to wash after fixing. The problems usually appear in the washing stage, or show up later when it is drying. I think this might be happening on your image because I can see outside the image area what looks like salt/gelatin coating that ends, then paper white....

    I also see some variation in the image itself that makes me think the proportion of silver to salt is not consistent... this could be caused by uneven application of the salt/gelatin or by uneven application of the sensitizer. It can be more of a problem if too much salt has been absorbed into the paper or a thick gelatin layer. I've experimented with various amounts of gelatin and had trouble getting consistent results with more than 2% unless the salting and sizing steps were separated, and the gelatin sizing step is let dry completely ( makes the gelatin insoluble ) before the salting step. The kinds of trouble were similar to what I see here. That's why I asked.

    Since you are in a hurry and probably don't have time for lots of testing or changing variables, here is an approach which might work and will keep most of your process unchanged. It will take longer because there is an extra drying step, but perhaps the result will be worth a try.

    1) coat your gelatin/salt solution, let dry completely.
    2) coat your AgNO3 ( add a little citric acid, if you are not already doing so ... maybe try 5% )
    3) wait about 10 or 15 minutes ( I'm not positive this is necessary, but I've never tried going to step 4 right away )
    4) wash in distilled water, very well: start with several rapid rinses to remove all the free silver nitrate, then wash at least 2x10minutes.
    5) let dry completely ( no heat )
    6) re-coat with 1% AgNO3 to provide the excess silver needed for printing out.
    7) let dry competely ( no heat )

    8) Print.

    9) When you are processing the printed image, wash it very well first, starting with a few rapid changes of water. This again removes excess silver nitrate. Then process as normal, including a weak salt solution like Niranjan mentioned.

    The reason this works is that after the silver chloride has formed in the paper (step 2) we immediately wash away all the excess silver nitrate, which is what is causing most of your trouble. Also, any salt that is left under the gelatin or in the lower layers of it is washed away. For the printing out to happen, there must be excess silver nitrate, which we provide in step 6, but it's going on top of the dried gelatin, its weak, and there's not much left for it to react with to cause trouble.
     
  13. Wayne

    Wayne Subscriber

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    No need to be a wanker about it, if you had said that in your original post it would have explained and justified your screaming and URGENT NEED FOR HELP just fine.
     
  14. NedL

    NedL Subscriber

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    BTW the approach I suggested is not my idea. It came from John Schaeffer, and I think I first read about it in post #2 in this thread.

    I have tried it a number of times with troublesome paper/sizing combinations, and it goes a long way toward solving various staining/fogging problems, but it does involve an extra drying step so it takes longer. It also does not solve every problem, and I didn't mean to imply it's a magic bullet, just something you might consider.
     
  15. pschwart

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    It would help to know all the specifics of your workflow, but the following should help:
    - use a salt bath for your first rinse. I use distilled water for this.
    - always use 2 15% fixer baths. There are complexes created in the initial fix that can only be removed using a 2nd fresh fixer
    - I strongly advise using all chemistry single-shot; that includes toners if you add these to your workflow. You can rotate you fixers, but hypo is cheap and
    you only need about 75ml for an 8x10 in a flat bottom tray.
     
  16. pschwart

    pschwart Member

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    It would help to know all the specifics of your workflow, but the following should help:
    - use a salt bath for your first rinse. I use distilled water for this.
    - always use 2 15% fixer baths. There are complexes created in the initial fix that can only be removed using a 2nd fresh fixer
    - I strongly advise using all chemistry single-shot; that includes toners if you add these to your workflow. You can rotate you fixers, but hypo is cheap and
    you only need about 75ml for an 8x10 in a flat bottom tray.
     
  17. Tom Taylor

    Tom Taylor Member

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    I experienced a grey stain when I coated the paper with silver nitrate without a citric acid additive and left the paper to air dry a little longer than I usually do before exposing. Citrate acid acts as a preservative but won't work forever. Expose as quickly as possible after drying. My paper dries in about 45 minutes and I typically expose within 30 to 45 minutes after that.

    Thomas
     
  18. Tom Taylor

    Tom Taylor Member

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    A quick addendum to my post above: The grey stain appeared on the dried paper and before exposing.

    Thomas
     
  19. OP
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    JOHN McMURTRIE

    JOHN McMURTRIE Member

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    Thanks for the excellent advise! I am using 1g of Gelatine dissolved in 100ml and 2g of Sodium Chloride for my coating solution. Sensitizing solution is 3g Silver Nitrate in 20ml plus 2g in Citric acid = 30ml. This mix is tried and tested but none of the results are producing anything with any good contrast. The fogging was not enough Fix for sure and the patches are my over generous amounts of sensitizer. I really believe my problems now are simply the time of year in the UK. Normally when it is cloudy in summer I get excellent blacks and good tonal range. I am just not getting anything good enough. I will try your method above adding the secondary coating of sensitiser after it is dry.
     
  20. NedL

    NedL Subscriber

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    OK! These are pretty much "usual" for salt printing. Your salting solution is 1% gelatin, 2% salt; your sensitizer is 10% AgNO3 and 6.7% CA.

    As you noted, the approach I mentioned might help with fog/stain but will not address contrast or how deep the darkest darks are. By reducing fog, It might brighten the highlights though, and that can make a real difference in whether the final print seems "flat". There are some ways to tinker with the proportions to increase contrast, but all of them will be minor tweaks compared to how it is exposed.

    I don't know what kind of negative you are using, but if it is transparent ( like film or pictorico ) there are some things you might try to improve contrast and separation of tones. I think of the printing as having 3 stages:

    first) bring out the darks and mids but highlights remain paper white and no highlight detail at all.
    second) once the darks and mids are most of the way to where you want them, bring out the highlight detail, and stop when the brightest whites you want to keep are starting to get some tone ... this is often the crucial step and has a big effect on what your highlights are going to be like at the end.
    third) a "blast" step which doesn't change the image very much but it "locks in" the darks. Without this step, the darks will fade more in processing and you won't get enough "depth of printing" for toners to work well. This might be a problem in February London if the sun is not out.

    On a sunny day, you can tape a piece of thin white paper over the printing frame glass ( a "diffuser" ). Then there are 4 levels of UV exposure:
    1. with diffuser, pointed at sky away from the sun
    2. with diffuser, pointed at the sun
    3. w/o diffuser, away from sun
    4. w/o diffuser, at the sun ( the "blast" )

    Depending on the weather and the negative, the first "darks" exposure might need 1) or 2). After an hour or two of 1), if it's not progressing fast enough, then switch to 2) and it might be ready to progress to the "highlights" exposure in 30 or 40 minutes.

    The point I'm trying to make is that you can use a very long, slow exposure to build up contrast. So if you are not already doing that, it's worth a try. If you can see that the darks are developing, it's okay to go 2 or 3 hours or more. If they aren't progressing much, then you switch to the next higher level of exposure, but the idea is not to touch the highlights even if it means if the exposure takes hours.

    On a cloudy day, things are trickier. If it's bright out, it might make the diffuser even more needed, but if it's a gloomy day there might not be enough UV to do the highlight exposure. You might be limited to "away from the sun" or "toward it" with no diffuser. But don't be afraid to let the "away from the sun" exposure go for hours if you can see that it's progressing. Any density you build up during this stage will be there when the highlight exposure starts... so anything at all will improve the separation of the darks compared to skipping this slow exposure step. Even if the darks don't get very dark it will still be an improvement.

    It can be hard to get a good "blast" if the sun is really low or if it goes behind thick clouds. I have a BLB setup but it doesn't work for the "blast" step... it makes the highlights muddy before the darks get locked in. I have quite a few failed prints where I just couldn't get enough sun to finish them off properly.

    Good luck! London forecast is for partly sunny tomorrow, so hopefully you have a good chance.
     
    Last edited: Feb 10, 2018
  21. Tom Taylor

    Tom Taylor Member

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    I don't think the OP really knows what he is doing, and that's the problem. In my case I had coated two sheets at the same time and let them dry and placed the second sheet in a paper safe in the darkroom while I exposed and processed the first. Thus I knew where the grey stain came from. Further, why in the world would one size Hahn Platinum Rag which is already sized? If you click on the Salt Print Gallery on my website, you'll bring up about 30 Canon G9 shots of salt prints all of which were printed on factory-sized paper - Lanaquerelle, Fabriano Aristico Extra White, Cot 320,... Same thing with Platinum Rag which I have been using since it was introduced.

    Thomas
     
  22. NedL

    NedL Subscriber

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    Hi Tom, I agree. I use gelatin to alter the tone of the print ( including if it is toned! ), but the purpose is not sizing. In fact I usually prefer the surface of the print without it.

    We fall into these traps... using lingo because that's what other people write. I've seen it called "combined salting/sizing solution" so often that I call it that too. Additions of gelatin or starch can change the way the surface appears -- but you're right: it's often not the main thing keeping the liquid from sinking into the paper!
     
  23. Ces1um

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    Did you get it all sorted out in the end?
     
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