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Thread: Salt Prints on Vellum or Gampi

  1. #1

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    Jan 2008
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    Salt Prints on Vellum or Gampi

    I'd like to try making salt prints on vellum or gampi papers. I'm hoping to get some tips from someone who has done this. Which paper did you use exactly? Can you recommend a source in the US? Did you size the paper, and how? Any other tips for someone doing his first alt process print?
    Thanks
    Chuck

  2. #2

    Join Date
    Jun 2014
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    1,270

    Re: Salt Prints on Vellum or Gampi

    I don't use gampi or vellum (but maybe I should give the gampi/kozo paper a try sometime). Instead, I use a variety of etching papers including fabriano artistico. I don't size my papers as I generally find it messy and too much hassle, but you can get somewhat better reflectance and therefore deeper blacks with sizing. However, for a first attempt, I would forego sizing as I find it makes it more difficult to achieve an even coating.

    I found that most papers will fog to various degrees unless some citric acid is added to the silver nitrate solution just prior to coating. A few drops of a 10% solution per milliliter of silver nitrate solution does the trick for me.

    Although several sources suggest brush coating can give good results, I never managed an even coating this way. I use a crude and simple puddle pusher made of pvc insulation tubing, the kind that is used for electrical installation. I'm sure a glass coating rod is superior, but this works for me.

    As for processing, acidifying the initial wash water with a pinch of citric acid (a 0.5% solution or thereabouts works nicely) vastly improves the effectiveness of the wash procedure, probably because citric acid is a moderately effective chelating agent. I personally use dilute, fresh rapid fixer for fixing salt prints, in a dilution of, say, 1+20, so roughly half the strength usually used for silver gelatin paper.

    I like to gold tone good prints with a thiourea gold toner, which gives a nice tone and seems to improve the durability of the print.

    Thorough washing is crucial for salt prints if they are intended to last. Poorly washed and untoned salt prints may deteriorate within a matter of months or even weeks.

    As to a suitable negative, you'll want to make some really long-scaled negatives. A negative that is slightly too contrasty to print at grade 0 paper is just about right. I could never coax a negative with enough density from my inkjet printer so I exclusively use silver negatives, preferably developed in a staining developer.

    Good luck with the process; it can be very rewarding, but also very challenging to iron out the kinks, even with the plethora of information you can find online. You'll find you may want to revisit sites with tips, tricks and experiences over and over again as you gain experience, as it turns out you need a certain absorptive capacity in order to be able to use the available information.

    Be sure to download the thesis of Ellie Young on salt printing; it's by far the most comprehensive and thorough resource I've been able to find online and it is really a reassure trove of information on all aspects of the process.

  3. #3

    Join Date
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    Re: Salt Prints on Vellum or Gampi

    Koraks, Thanks so much for your sharing your knowledge.
    I finally jumped into this over the past few days and got some encouraging prints. I've started with the B&S Salt Print Kit for simplicity and Vellum from "Paper & More" (White Translucent Vellum Paper 29#, 8 1/2" x 11"). Total cost including shipping was just over $100. That should get me about 50 8"X10" prints. Since I'm a beginner at alt process printing I decided to skip the gold toner to save some expense. I chose brush coating over the puddle pusher because that seems to be what most people do. I think I like seeing the brush stroke, too. That seems to be the right choice for this paper because it buckles pretty dramatically during the coating. I imagine I will try a more standard paper sometime and try the rod method then.

    Here are the first decent results. 2% salt solution, 12% silver nitrate. No other additives yet. On the next try I will add some Potassium Dichromate for more contrast and try the Citric Acid to see what that does. It looks like getting the paper flat will be an issue. Maybe just a larger sheet, since the problem is only along the edges. Humidity is probably a factor too.

    IPhone photos, because I don't scan.

    Click image for larger version. 

Name:	Falls Salt Print.jpg 
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ID:	174522
    8"X10" HP5, Pyrocat HD. 40 drops 2%salt, 40 drops 12% silver nitrate, 40 minutes bright overcast sunlight
    Click image for larger version. 

Name:	Benny Salt Print.jpg 
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ID:	174523
    5"X7" HP5, Pyrocat HD, 18 drops 2% salt, 18 drops 12% silver nitrate, 25 minutes bright overcast sunlight

    Comments welcome.
    Thanks

  4. #4

    Join Date
    Jun 2014
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    Re: Salt Prints on Vellum or Gampi

    Those are excellent results for a first try indeed! In fact, they are a million times better than my initial attempts when I first tried this process...

    If you decide you want to improve on things (as I imagine you're already quite satisfied where you are now), you may consider the following:

    * If you find dmax lacking, you probably need negatives with even a longer tonal scale so you can increase exposure without letting the highlights drop too far into dark grey.
    * I found that adding dichromate create more problems than it solved, but I never tested very extensively. Dichromate when added to the silver solution will throw down an orange/brown precipitate that causes issues with coating uneveness. Likewise, I recall having issues with uneven coating as well when I added the dichromate to the salt mix, as the same precipitate will form as soon as you brush on the silver solution. I gave up on this avenue and decided for myself that creating negatives with the required tonal scale was a superior and more straightforward solution.
    * If you desire more contrast, you can also (apart from the above) try different papers. I did a quick test with some very thin, tissue-like papers a couple of weeks ago. I found they worked quite nicely, but due to the translucency of the paper, the contrast and dmax appear significantly lower than on more opaque papers.

    Despite using a brush, your coating looks quite nice and even; I never got it to work that well with a brush, hence my recommendation to use a puddle pusher. However, if this approach works for you, stick with it!

    One final note: I found that processing is quite iffy with salt printing. It's very easy to rinse or fix insufficiently, especially with heavier papers. In this respect, kozo/tissue-like papers are superior as they allow for relatively rapid processing. My processing scheme for heavier papers currently looks a bit like this:
    * Rinse in a tray of water with ca. 0.5% citric acid for about 3 minutes, rocking the tray continuously
    * Repeat first step with fresh water + 0.5% citric acid
    * Quick rinse in tap water to neutralize pH.
    * Tone in thiourea gold toner (optional). Toning to completion takes about 8-12 minutes with heavier papers in my experience. I found that gold toning before fixing dramatically increases the risk of fogging, but I also found it's the only way to get the neutral-cool tone that I quite like.
    * Fix for 5 minutes in freshly made alt process fixer, which for me is: 1tbsp of sodium thiosulfate with a pinch of sodium bicarbonate and a pinch of sodium sulfite added to 300ml of water.
    * Rinse in tap water briefly.
    * Repeat fix step with fresh fixer; the fixer I use is relatively weak. As you can read above, I also sometimes use a dilute rapid fixer, which works as well, but seems to increase the risk of staining particularly if gold toning is applied prior to fixing, and it also increases the risk of bleaching the print if it is fixed too long.
    * Rinse print in a tray of tap water for about a minute or maybe 2; not very critical.
    * Wash the print for about a minute in water with a pinch (let's say 1%) of sodium sulfite added to it.
    * Wash the print thoroughly for at least 30 minutes, but preferably longer.
    * Hang up to dry. When thoroughly dry, I iron my prints with a clothes iron at its highest temperature setting. Just shove the print in-between two sheets of clean newsprint and iron both sides for a minute or so. The print comes out without any waviness or curling, even when heavier papers are used. Ironing also shifts the tone noticeably to neutral, which is quite pronounced with untoned prints.

    In order to see if your processing regime is effective, I recommend masking the non-image areas of your prints so you can check that no fog occurs during the final wash or after a longer period of time. Before I started doing this myself, I never was aware of the fact that my processing (particularly the initial rinse and fixing steps) was absolutely insufficient - until my prints began to fade and fog in the highlights...
    The silver chloride that is at the core of salt printing and the byproducts generated during processing (particularly gold toning and fixing) seem to adhere to the paper fibers very well, making fog a huge issue in my experience; much more so than with e.g. Van Dyke browns. If you search online, you'll find numerous examples and complaints about fog appearing in highlights and masked non-image areas during the final wash stage or during/after drying. Improper processing is virtually always the culprit.

  5. #5

    Join Date
    Jan 2008
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    Morgantown, WV
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    Re: Salt Prints on Vellum or Gampi

    Thanks so much. I am going to print this post so I can refer to it when I'm in the darkroom.

    I would like to see more contrast. I'll try the dichromate keeping in mind your comments. I'll also try to tailor my next negatives to this process. I'll order some toner to try to increase D-Max when I feel like I have too much money. I hope to try again in the next few days. Since I'm exposing by sunlight, I'm at the mercy of the weather.

    Thanks again!
    This is fun!

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