View Full Version : salt printing, take 1

06-16-2013, 10:38 PM
Each yeah I teach AP Chemistry I have the fortune to have one month to work on projects. I, of course, do a photo project. This year we made pinhole cameras and salt printed our negatives. This was my first experience with salt printing, and quite a learning experience as I decided to make a few of my own.

The main issue I had was with the silver nitrate fogging my paper. I used Canson watercolor paper; it's cheap and available locally. My final successful results came when I acidified my paper in 1M HCl, sized it in 3% gelatin, and then sensitized it with 10% Silver nitrate + 5% Citric acid. When I get some new paper I'll attempt to sensitize with silver nitrate + citric acid without acidifying or sizing as I have not tested that. If I could leave out the acidifying and sizing process it would save a load of time in the process.

The other potential issue is that I used Kodafix, 20mL concentrate + 780mL water. It seems that then general consensus is to use hypo as photo fixer is too aggressive. Kodafix is all I have currently and as I have the time, I figured I'd use it and see what comes out.

I've tried to match the colors and levels as much as possible with these renditions. I hope you enjoy them and welcome any advice on how to proceed for take 2.

http://farm6.staticflickr.com/5507/9061477781_d45c0b3982_s.jpg (http://www.flickr.com/photos/jasonthomas/9061477781/)
salt001 (http://www.flickr.com/photos/jasonthomas/9061477781/) by jason_in_gboro (http://www.flickr.com/people/jasonthomas/), on Flickr

http://farm8.staticflickr.com/7331/9063706658_424a489f84_s.jpg (http://www.flickr.com/photos/jasonthomas/9063706658/)
salt002 (http://www.flickr.com/photos/jasonthomas/9063706658/) by jason_in_gboro (http://www.flickr.com/people/jasonthomas/), on Flickr

06-17-2013, 12:09 AM
Great job! I look forward to reading about "take 2".

06-18-2013, 12:08 PM
Thanks, Ned. And a couple of questions for those that are more experienced with this process...

1. Would using hypo instead of dilute photo fixer result in deeper shadows?
2. Would any delay between coating the paper and exposing cause shadows that are not as deep?

11-22-2013, 01:05 AM
Hi Jason, it's been a while since I printed salt, but it was the first process I put a ton of time into testing. I have never used dilute photo fixer, so I can't say for sure about that, but in my experience I have never noticed fixer (sodium thiosulfate) affecting the image other than the typical lightening that it does (only to dry back down later). I think your shadows are going to depend on your negatives more than anything. (Although sometimes double coating your paper with silver nitrate can help with shadows, but it can bring down your highlights, too...) Proper exposure and processing can really make a difference. I always work from digital negs, so I can tweak things and add curves, but a dense, contrasty neg works best. One of the bits of advice out there that I do adhere to (even if it only seems to work in my head) is a shade/sun exposure mix. I usually expose about 4 minutes in the shade, then about 1.5 minutes in direct sun.

I finally settled on using Cranes Executive paper (a 32 lb stationary - "kid" finish if you can find it) with a 2% ammonium chloride soak - single salt, no acidifying, no sizing. I gave a workshop over the summer and prepped a bunch of different paper for it and found that Fabriano Artistico hot press (120lb, bright white) worked really well too, same 2% ammonium chloride, no other prep. Personally I've come to believe - 1). People tend to use too heavy of weight paper, and 2). Gelatin sizing is for the birds... an unnecessary step perpetuated by the "experts". Good quality modern papers are more than adequately sized. Not to mention my prints seemed to gain a bit of sharpness once I dropped the gelatin step.

Oh, I also use a 15% silver solution with no citric, and glass rod coating method.
(The Cranes requires two heavy coats of silver or it just won't work).

If you want to see some of my stuff you can check it out HERE (http://oddlittleworld.com/salted-paper).

Best of luck, salt is fun, and will always be my first historic process "love" - in fact, it was a salt print I won in a raffle that got me going on all this... 20 years ago! (Though I didn't start printing until 5 years ago). Once I started testing things (gun bichromate included), I found that simplifying was most effective, and I am getting the results I want with next to none of the extra steps a lot of people insist are necessary. It's what works for me.

Cheers! dm