It seems like everyone is loving on salt prints lately! In the last few days Christina Z. Anderson and J. Keith Schreiber have posted some very in-depth and interesting material about salt on the Alternative Processes Facebook group. Really, Spiders, that's a great place to be if you're working in alt processes.
Christina Z. Anderson's post (HERE) was about the fancy-schmancy new paper by Hahnemühle: Platinum Rag. It's designed for (duh) platinum printing, but also produces good results for all manner of other processes. Diana Bloomfield used it to do a multi-layer gum print without any additional sizing! That's pretty impressive. Aside from the coolness of this (expensive) new paper, I enjoyed seeing someone else doing the same kind of rigorous testing that I'm doing with chemistry. The difference between gelatinized and non-gelatinzied paper is something I'm also going to end up testing, too.
Keith Schreiber's post (HERE) is more a general thing about salt printing. He talks about how it can have an even longer tonal range than platnium printing, which I didn't actually know. Kinda makes me wonder what the point of platinum is, since everyone always gushes about it's incredible tonal range. Plus, at the end of his post, he links a Salt Printing PDF from a printer working at the Fox Talbot Museum. More fun things to study! I also like that he provides very clear examples of various toning effects. It's nice to see well-documented information. I feel that's a big downside to the book by Christopher James. He gives examples of toned photographs, or variations on a process, but he doesn't provide (often probably can't, since he sources his examples from numerous other artists) side-by-side examples so you can see the difference between Approach A and Approach B. That side-by-side is hugely important to me.
Tuesday, February 23, 2016
Thursday, February 11, 2016
|6 hour exposure of dichromate test print|
So, I made a small salt print (the normal way, with 3% kosher salt), then added a drop of 5% ammonium dichromate to the top left and a drop of 5% potassium dichromate to the bottom right. In the middle of the print, I sprinkled the cream of tartar. Cream of tartar is chemically potassium bitartrate (KC4H5O6), which is a form of tartaric acid.
Again, my discussions with Johannes suggested that adding tartaric acid to a salt print should produce some variations of color. In the future, I'll test this further by mixing up a tartaric acid solution, probably just cream of tartar in water. Then I'll coat that solution onto a salted paper, in addition to regular sodium chloride.
Just to add some variety, I put a Red Nightshade leaf onto the salted, dichromated and tartarated paper. Then I exposed the paper for about 6 hours in sunlight, from dawn till around noon. Once I'd scanned the image after the first exposure, I let it sit out in sunlight (without the leaf) for another 2 days before I scanned it again. I've continued to leave it unprotected, so I'll be scanning again in a few weeks.
After 2 hours, the red color in the dichromate was lovely. Unfortunately, after the two days of sunlight, the dichromate had turned mostly violet, while the silver was the expected green. The cream of tartar had left slightly darker spots, but I'm not sure if that's just because it affected the original 6-hour exposure, or if it chemically created a reaction. Further testing is required!
I also did some tests on Potassium Iodide and Potassium Chloride salt prints. I'll have those results up on Flickr in the near future. They haven't been washed and fixed, yet. That's on the agenda for today, though!
Thursday, February 4, 2016
|Potassium Dichromate (K2Cr2O7): a rather nasty |
but potentially beautiful little chemical
Serdar informed me that he had previously made images using silver citrate, silver tartarate and silver carbonate instead of a silver halide. Unfortunately, he did not have any scans of these images, but he did say that he found them either too low in d-max, or too high in contrast for negative printing. Here's a list of what he said he used to create the different silver compounds
Silver Citrate = Silver Nitrate + Sodium Citrate
Silver Tartarate = Silver Nitrate + Tartaric Acid (maybe from cream of tartar?)
Silver Carbonate = Silver Nitrate + Sodium Carbonate (soda ash)
Basically, all that means that silver compounds aside from halides can likely be used to print visible images. I'm going to give these a try most definitely, especially since soda ash and cream of tartar are so easy to get. Sodium citrate is available from the university lab, so I'll be giving that a shot as well.
Mark Osterman discussed with me the fixing ability of potassium iodide. Previously, I had fixed several prints in 5.6% potassium iodide, but not noticed any significant difference in the result from the more traditional sodium thiosulfate fixer. If anything, the potassium iodide leaves a warmer tone in the fixed image, but both fixing processes remove a lot of the color from a salt printed image. Mark says that, in theory, a salt print fixed in potassium iodide should turn yellow as the silver is converted to silver iodide. He also recommended that I find a copy of Records of the Dawn of Photography, which is a published version of Talbot's early notebooks. Unfortunately, that book sells for over four hundred dollars and there aren't any circulating copies in my local libraries. I may be able to visit a nearby university (I'm in friggin Boston) and make scans or notes. I'll have to look into that.
The most interesting conversation, though, was with Johannes Schmidt. He told me that he'd run across some literature a bit over a year ago that suggested adding salts of organic acids to the standard sodium chloride and silver nitrate mixture used in salt printing could alter the color of the print. He mixed up solutions of potassium or sodium compounds of acetate, ascorbate, formate, succinate and tartrate. These solutions were applied along with sodium chloride to paper, which was then sensitized with silver nitrate. He also tested the effects of dichromate, iodine and photographic developer on the silvered paper. There are some truly lovely results, especially from the dichromate. In fact, I'm going to borrow some ammonium dichromate from the university and do some tests of my own with applying it to salt prints.
Who knows, maybe I'll give up on this whole "photogram" thing and just create my images through pure chemistry. Chemigrams are popular, right?
Wednesday, February 3, 2016
Well, Spiders, I'm a bit late with today's blog. Six days late, actually. Unfortunately the only excuse I have is that I simply didn't get around to editing all these images and patching them together into a cohesive scan. The beginning of the semester has been a little stressful, and I've been trying to keep it all together. But, I do hope to have an entry for tomorrow, too!
After my experiments with photograms, I decided I needed something more controlled to really do a proper test of these different halide solutions. So, I created a little digital "test sheet"that has a smooth white-to-black gradient, a 15% medium grey bar, and a six-step zone chart that has 100%, 80%, 60%, 40%, 20% and 0% black. Using this test sheet, I can tell if one compound has more contrast, less contrast, exposes faster or slower, and get a much wider range of tonality than by using photograms. I'm also controlling the process further by printing in one of the university's UV exposure boxes, instead of in sunlight.
So far, my results aren't mind-blowing or anything.
The potassium iodide (KI) is really.. ugly. I mean, there's just not anything redeeming about it, especially not once it's been fixed. Maybe it's nice in the "latent" form, just after exposure, but even just a salt water wash makes it muddy and unpleasant. Fixing it just turns it to a dull, rather hideous brown.
Ammonium chloride (NH4Cl) is extremely similar to sodium chloride (NaCl). The only difference I can see, and it's quite subtle, is that the ammonium chloride seems to be a little bit warmer. There are two tests for ammonium chloride because the first test had some pretty hideous staining. The second test, though, was slightly compromised because I waited a full day between exposing it and fixing it. This almost certainly caused some fogging in the paper before the fixing.
Bromo-Iodizer has the most interesting results, providing warm yellow highlights and soft brown shadows. I can certainly see some uses for this coloration, but I'm personally not a huge fan. I do like the long-exposure greens that it produces, but I'm not sure if I like it enough to continue working with the Bromo-Iodizer. It's quite nasty stuff, and I may be able to get similar results by simply using potassium bromide and potassium iodide together, without the presence of alcohol or cadmium.
Assuming that I've recovered from my current head-cold by tomorrow, I'll be giving a test to potassium chloride and potassium bromide, both of which arrived recently. I was able to mix up a 3% solution of both, coat and dry some test sheets, but didn't have time to apply the silver nitrate or do a test exposure. So those salted papers are waiting for me in the lab!
Toss some positive vibes my way, Spiders. I could use 'em for this little plague.