Salt Prints blues

krisb1981 · Nov 17, 2014

Hi all,
I have been experimenting with salt printing with mixed results. Let me go over the process I use and then describe my issues.
I use 12% silver nitrate solution (12g Silver Nitrate crystals dissolved in 100g distilled water) for salt base I use 2g sea salt mixed in 100g distilled water. All is fine so far. Now I use 120 pound watercolor non acid archival grade paper and I float it in the salt water. I let it dry completely for few hours. Then, I apply the silver in low incandescent light = 15 watt bulb. I let it hang to dry and now the issue starts. The paper, before it even dries, starts turning brown, There is no UV light or stray sunlight coming in to hit the paper. For one batch I thing I might have applied too much silver (thick coat) and those papers seemed worse than those with thinner coat. My question is, can the amount of silver applied cause premature browning>? On my other batch I used different brush and applied less silver and those seemed better, but I still get light brown base to the paper, instead of white base and browning only when the UV hits it. Any thoughts?
Thank you

Andrew O'Neill · Nov 17, 2014

I don't make salt prints but whenever I coat a paper with a sensitizer, and it dries a dark yellow/brown, the issue is the paper. The paper buffers can mess things up. Soaking the paper in a 10% acidic solution (such as sulfamic acid), washing thoroughly, drying, takes care of the issue for me. As I know nothing about salt printing, this may not help you. You could try this (vinegar might even work as an acidifier) or a different paper.

NedL · Nov 17, 2014

Yes Andrew is right. Adding some citric acid to the silver solution before coating can also solve this. The paper might still fog after a day or two but you will have time enough to make your print. The tradeoff is that if you add CA to your 100ml of already-mixed AgNO3, it might not keep as well, so it is better to add it only to the small amount you are about to brush on the paper.

krisb1981 · Nov 17, 2014

What paper do you use for your projects?

NedL · Nov 17, 2014

Someone with more experience should answer because I have only tried 2 papers so far. I know Jim Noel likes to use thinner papers. I don't really have a favorite and am looking forward to trying others.

Canson Universal Sketch, requires between 3 and 4% citric acid in the silver solution to get bright white highlights. There was additional visual improvement in highlights up to 4.5%, and no fogging up to at least 22 hours after coating with 6% CA in the silver nitrate solution. I started using 6% after these tests. Some kinds of sea salt ( I have only tested 4 kinds ) still produce slight pinkish background fog even with 6% CA.

The other paper I have tried is Lana Aquarelle 140lb. It came with this note:

"Note: Lana Aquarele varies in pH slightly, from batch to batch. Some printers find that soaking this paper in a 5% solution of Citric Acid or Oxalic Acid for 3-5 minutes will give an increase in printing speed and density."

I think that note is probably aimed at platinum printers, but I've been using 0.5% CA in the salt solution and 5% CA in the silver nitrate solution, and have had no problems of any kind with fogging. I have noticed that changing the amount of gelatin on this paper does not make as much difference as it does on the Universal Sketch, although it does affect the final tones.

I would be interested to know what the favorite paper of other salt printers is. I have some Revere Platinum that I am going to try next.

Barry S · Nov 17, 2014

Two possibilities-- the paper may be unsuitable, or your sea salt may have some organic materials that are reacting with the silver nitrate. The usual suspect is the paper, so I suggest you try some other types. I've had good success with Fabriano Artistico Extra White. You may also want to try some Kosher salt--it's just salt with no iodide or organic materials.

Jim Noel · Nov 17, 2014

Your paper is definitely the problem. This,and most alternative processes , are acidic processes, thus "non-acidic" papers cause problems. Do as suggested and soak the paper in an organic acid such as citric prior to use, or change to a non-buffered paper. As mentioned, I prefer very light weight papers primarily because this is what was used by the early practitioners of this process. Theirs was sized with gelatin so I include gelatin in my salting solution. I use 100% cotton or linen stationery as light in weight as I can find. Most common is 24lb. I usually find this at Staples. I have tried all of the papers sold by Bostick and Sullivan and they all work. I must note that I haven't found an art store where the employees are really knowledgeable about the papers they stock. It is important to read the label on the original package.

Good luck!

Jim Noel · Nov 17, 2014

Barry S said:
Two possibilities-- the paper may be unsuitable, or your sea salt may have some organic materials that are reacting with the silver nitrate. The usual suspect is the paper, so I suggest you try some other types. I've had good success with Fabriano Artistico Extra White. You may also want to try some Kosher salt--it's just salt with no iodide or organic materials.

Impurities in salt are not usually a big problem, although iodized salt frequently is. Kosher salt and non-iodized sea salt work well. These are what I use when I teach the process. My real preference is filtered sea water which I use when I take the time to drive to the coast and get some. Of course is is full of "impurities", but these provide trace elements which cause some interesting minute changes in the appearance of the image.

krisb1981 · Nov 17, 2014

That helps a lot. Thank you. Can I just float the paper in say 4-6% citric acid solution or do I need to soak it, rinse and dry?

Mainecoonmaniac · Nov 17, 2014

I've been lucky in picking paper for salt printing without buffers. But I wonder if you can mix citric acid in the salt solution then soaking the paper and letting it dry?

Andrew O'Neill · Nov 17, 2014

Soak the paper in the acid for at least 10 minutes followed by a thorough washing. Use when dry. I use Rising Stonehenge. You can try putting a weak acidic solution in your sensitizer. It was always hit and miss when I did this, though.

pdeeh · Nov 17, 2014

Jim Noel said:
Impurities in salt are not usually a big problem, although iodized salt frequently is ... My real preference is filtered sea water

Surely sea water contains iodine and iodides though?

cliveh · Nov 17, 2014

pdeeh said:
Surely sea water contains iodine and iodides though?

Why would that be a problem? Iodine is a halogen.

pdeeh · Nov 17, 2014

That's precisely why I'm asking, clive.

All the literature and online advice I have read cautions against the use of iodised salt, yet I have also seen a number of references to the use of sea water for salted paper, here and elsewhere.

It is a bit clearer why it might be a problem with an actual emulsion (because, I presume, of the restraining action of iodides) but I simply don't yet understand enough of the chemistry involved in development and POP to be clear about the differences.

It would be nice for a PE or similar to drop in on this discussion for a definitive clarification.

cliveh · Nov 17, 2014

pdeeh said:
That's precisely why I'm asking, clive.

All the literature and online advice I have read cautions against the use of iodised salt, yet I have also seen a number of references to the use of sea water for salted paper, here and elsewhere.

It is a bit clearer why it might be a problem with an actual emulsion (because, I presume, of the restraining action of iodides) but I simply don't yet understand enough of the chemistry involved in development and POP to be clear about the differences.

It would be nice for a PE or similar to drop in on this discussion for a definitive clarification.

What do you mean by the restraining action of iodides?

NedL · Nov 17, 2014

For what it's worth, I made my first few salt prints with plain old Morten's iodized salt, a very common brand in the U.S. and it worked just fine. Then I tried some kosher salt, and it was fine too but I did not like the resulting color ( that's "colour" for you, pdeeh ) as much. Each salt I've tried has been a little different. I think one of the wonderful things about salt printing is all the variables that lead to subtle differences: paper, type of salt, amount of citric acid, citrates or other "additives", amount of gelatin, exposed slow or fast. And that's all before the toning! Right now I'm using alaea salt from Hawaii, which I bought just for the fun of trying it out and it actually surprised me and turns out to be my favorite colo(u)r so far.

Today, I used gold borax toner, followed by just enough short weak gold thiocyanate toner to push the colors a bit toward purple. I've been fussing around with toning for about a month now and am getting a handle on it. But the truth is that the differences are subtle and my friends who look at them don't prefer one or the other strongly. I'm down into the details that matter to me but that the average person looking at the print won't notice very much. All these differences are easier to see with the prints side by side. I'm really glad I started doing this.

Andrew O'Neill · Nov 17, 2014

( that's "colour" for you, pdeeh )

…and for all of us Canucks up here…

my favorite colo(u)r so far.

favourite...

NedL · Nov 17, 2014

Thanks neighbo(u)r!

Salt Prints blues

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