Salt Print. Fog or stain?

Discussion in 'Alternative Processes' started by ColinRH, Oct 7, 2010.

  1. ColinRH

    ColinRH Subscriber

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    I have been trying my hand at salt prints recently thinking I was doing OK except that High lights were not being attained.
    To cut a very long story short I am now trying to eliminate fog/stain on the paper.

    I make 4 x 1 1/2 inch square pieces of paper which are coated with a 1 inch strip of sensitiser. Without giving any UV exposure they are immediately
    rinsed and then fixed in hypo. After washing they are air dried and within 3 -4 hours the sensitised strip begins to show a tone which increases
    in density over the next hours and days. This suggests to me that it is caused by insufficient fixing, but of course it may be many other things.
    This is my procedure
    1) 2 pieces of paper are coated in a darkened room. I have no darkroom but use a darkened bathroom with the door slightly open to give me just enough
    light to see.
    2) The paper is then dried for 30 seconds with a hair dryer on low.
    3) the paper is then rinsed in tap water for 2-3 minutes. In the very low light I cannot see when the 'milkiness' clears but 2-3 minutes seemed right
    when I used brighter light.
    4) the samples are then immediately put into a 10% solution of hypo and given continuous agitation for 3 minutes. At this point 1 piece is taken out
    leaving the second piece in the hypo until 5 minutes have elapsed.
    5) both pieces of paper are then given a wash in trays; sloshing water and 3 changes for about 10 minutes. These are after all tests and not achival
    pieces.
    6) they are then air dried.

    The other 2 pieces of paper are treated in exactly the same way but fixed in 15% hypo. Both hypo baths are fresh and dumped after being used for
    just those two pieces of paper. Is the tonality which appears likely to be fog or stain - and how do you tell one from the other?
    After all I have read I find it difficult to believe that the paper is not fixed properly. The 3 minute pieces start to show tone first.
    I use COT 320 with 2% gelatin with 2% Sod. Chloride; 12% silver nitrate with 6% citric acid; straight hypo.

    Very sorry about the length. Observations/help would be appreciated Colin.
     
  2. Robert Hall

    Robert Hall Subscriber

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    Hair dryer... Bad.

    Heat sensitive, usually makes a nice fogged piece of paper.

    Hypo, 10 minutes is recommended.

    Paper, try a second type and try each of these "suggestions" one at a time, of course.

    Let us know,

    R
     
  3. Barry S

    Barry S Member

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    It's definitely inadequate fixing. I use a hair dryer on low for drying and haven't had any problems. Here's my fix and wash procedure:

    8. Wash print in 2% sodium chloride solution for 3 minutes
    9. Fix print in 15% sodium thiosulfate (hypo) plus 0.2% sodium carbonate for 3 minutes (fixer bath #1)
    10. Fix print in 15% sodium thiosulfate (hypo) plus 0.2% sodium carbonate for 3 minutes (fixer bath #2)
    11. Wash print for 2-3 minutes in water
    12. Wash in Hypo-Clear (e.g., PermaWash) as recommended
    13. Wash print for 20-30 minutes in water (thicker papers require more washing)
     
  4. Robert Hall

    Robert Hall Subscriber

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    Heat. Still not a good thing. Easy to damage the gelatin. Easy to draw moisture out in an uneven fashion. I would recommend staying away from it until you have your process down.

    Quote from a knowledgeable gentleman, Liam Lawless..

    "Coated papers must be fully dried before printing, by which I mean that their humidity should reach equilibrium with the air around them. Do not, therefore, use heat as making them too dry will have an adverse effect on the image characteristics, even if it doesn't melt the emulsion."

    Only a suggestion to keep things that may damage prints to a minimum.

    Regards,
     
  5. ColinRH

    ColinRH Subscriber

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    Thanks Robert and Barry.
    Robert - If applied heat is not good, how long does it take for the paper to dry? It seems to fog fairly quickly if not used soon after coating.

    Barry - Thanks for points 8 9 10. As I am only doing small tests do you think it necessary to give the full archival final wash to elimate any fog/stain?
     
  6. Ross Chambers

    Ross Chambers Member

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    I'm not doing too badly at present after lots of failures.

    Briefly: I salt ahead and the paper seems OK for several weeks.

    When sensitising I look at the sky (I have only the sun for UV) and if it looks OK I coat under a red safelight, turn on an electric heater on the floor at a lowish level, have a shower, walk down to buy a newspaper.

    The first coat is dry by the time I return, so I make the second coat of sensitiser, leave the heater on, have breakfast, the paper is usually dry by then (don't rush breakfast).

    I ignore all the books and face the print package directly into the sunlight (heresy, but it works).

    Alternate water washes between 2 trays (water renewed each time) for 6 times.

    In Sodium Thiosulphate 50gm per litre fixer I gently agitate 10 minutes. Wash for 30 minutes in print washer (Paterson continuous flow flat device) I find it interesting to compare the amount of fixer absorbed by the print, 2 sheets 7x9 Inches will suck up 50-70 ml.

    Regards - Ross
     
  7. Robert Hall

    Robert Hall Subscriber

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    As with all good questions, the answer is "It depends" :smile:


    What you want is to have the emulsion match present humidity. I let mine go overnight. Perhaps difficult when you are short on time or just really want to make a print.

    A lot would depend on how heavy or thick the gelatin is, and what the humidity is. I have been able to leave mine for well over a week with no fogging and only a slight yellowing of the emulsion, but that clears with little trouble after processing.

    I also like to gold tone my prints before fixing, not after. (are you gold toning your prints?)
     
  8. Robert Hall

    Robert Hall Subscriber

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    Just as an aside, I use 150 grams per liter and change the fix every 4 prints. Fixing for at least 5 minutes, usually closer to 10.
     
  9. Loris Medici

    Loris Medici Member

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    Not that I'm a salt printing expert, BUT, I don't think you need that much sodium thiosulfate in order to successfully fix salt prints; there will be very little remaining silver halide after washing out unexposed sensitizer in the first couple of water changes, therefore, I think a much weaker fixer (3-5%?) should work well enough and w/o any adverse effects. 150g sodium thiosulfate for every four prints sounds a little too wasteful, IMHO...

    Just my 2c,
    Regards,
    Loris.
     
  10. Robert Hall

    Robert Hall Subscriber

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    Loris,

    You're experience speaks for itself and you're suggestions are always welcome.

    I find it quite interesting that there are so many formula for salt printing, each a bit different than the others. I guess it goes to show how flexible the salt printing method can be.

    I would suggest that if one was really concerned about fixing it would be easy to test with the typical residual fixer tests we use on paper such as selenium toner or sulfide toners on rebate areas of the prints.

    As per Richard Knoppow's statements on what is considered "archival" and how much paper fix can actually fix out, it seems to me more a matter of if you are the type to wear a belt and suspenders. :smile:

    For me it is important that the prints have good longevity and the fix is very inexpensive here as I have a local source that costs about a dollar a pound.

    Perhaps next time through, I will do some fix tests to see what I can see.

    Many thinks.
     
  11. Jim Noel

    Jim Noel Member

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    Yes, there are a lot of formulas out there. Some get so complicated as to make this extremely simple printing process complicated.
    When I began salt printing a good many years ago I decided to research the original methods and that is what I use. Think of the technology of the era, and don't go beyond it. The chemistry is simpler and far less finicky. I use non-iodized sea salt, technical grade silver nitrate and insure that the paper is ultra light weight (20 lb or less) and gelatin sized. Beautiful deep browns and clear highlight result. I learned this from a hand written photographers printing diary from the 18th Century.
    My only concession to the 20th Century is my HID UV exposure unit which provides consistency of exposure. If I need more contrast, I use my fluorescent UV box.
     
  12. Jim Noel

    Jim Noel Member

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    Typo error - that should read 19th, not 18th century.
     
  13. Peter Schrager

    Peter Schrager Subscriber

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    jim- so what papers are you using?? just curious as I have found arches platine works the best for me
    thanks,Peter
     
  14. Robert Hall

    Robert Hall Subscriber

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    Jim,

    Post some pics!
     
  15. Robert Hall

    Robert Hall Subscriber

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    Peter,

    I have used several papers and most work, but I like platine as well.