There’s been some interesting discussion about salt printing lately, both on the Facebook Alternative Photographic Process group and on the venerable old alt-photo-process email list. I am by no means an expert on the subject, but I did have the pleasure in the late 90s of assisting Michael Gray of the Fox Talbot Museum at a workshop he gave at the Center for Creative Photography (UA Tucson) where I was employed at the time. The discussion on FB primarily concerned toning, while the email group discussion was about sizing (or not) of paper. I made some contributions to the discussions that I have recapped here for easy reference in the future.

I work primarily with the platinum/palladium process using original large-format negatives exposed and developed with the requirements of that process in mind. An ideal negative for a straight palladium print (my usual choice) on most papers has a density range of about 1.8 with a maximum density of about 2.1 – 2.4. Sometimes, not too often, I misjudge exposure and/or development and end up with a “bulletproof” negative that is beyond the range of what I can print in palladium. This is where salt printing can be a useful alternative for me. Because it is or can be a longer scale process than Pt/Pd, I can print negatives as salt prints that I can’t (or can only with great difficulty) as palladium prints. I have found that a salt print exposed in full sun has a tonal scale of 2.4 or longer due to the self-masking effect of the printing-out process.

I have not done a lot of salt printing, but I did experiment with it a bit in 1999 shortly after the workshop, and again in 2009. As of this writing, the 2009 prints have gone missing, though I know they are here somewhere. The prints shown here are all from 1999 and illustrate a few of the variations in the color of the final image that are possible. These are the successful ones – I had many failures. Click on the small images to open a larger version.



And for comparison, here is a palladium print of the same negative for which I made a shadow mask to maintain some detail in the dark area at lower right. A slightly stronger mask might have been useful to pull out even more detail. In the end I preferred the palladium print of this image.

1998810378_Pd


The other issue discussed was whether or not to size the paper and if so how to do it.  Christina Anderson began a thread on the alt-photo-process email list asking salt printers whether or not they sized their paper. Of those who responded, 6 said yes, one said sometimes, and I said I did not. Of the 7 who do use sizing, most add it to the salting solution. Only one said that he presized his paper. A look at the literature I have on the subject also showed much disagreement.

I do think there is a little confusion about exactly what we are talking about here. On the one hand there is sizing of the paper itself, and on the other there is sizing added to the salting solution. I have just been looking over half a dozen or so book chapters and articles on slat printing and no two of them are in agreement on much of anything. Some, such as James Reilly, William Crawford, John Schaefer, and Christopher James, add gelatin or starch (arrowroot) to the salt solution but no 2 formulas are the same. James does mention that “Talbot had no need to size his papers with gelatin because the fine stationary of that time was manufactured with gelatin and other organic binders in the rag fibers.” (I’ll come back to this.) Terry King and Wynn White size with gelatin prior to salting and sensitizing.

Even the silver nitrate concentration varies from 10% (James) to 20% (James – high altitude formula), though most are 12 or 13%.

So back to the question of whether size is needed or not. At Michael Gray’s workshop, we did not apply additional sizing at all, and there is no reference to it in my notes, nor is there in the pamphlet from the Fox Talbot Museum that I have. I suspect that it really depends on the particular paper – how and with what is it sized in the manufacturing process. If it is sized with gelatin, especially if it is surface sized with gelation, I seriously doubt that it would need additional gelatin sizing. However, if it is sized with aquapel, a synthetic size that seems to be becoming more common, that would be another story. The prints that I made in the late 90s were on Crane’s Platinotype which I if I remember right was alum-rosin sized. That may be why I did not need any additional sizing.


Here are my workshop notes. I typed this up many years later. I think the toner formulas may have come from elsewhere.

Salt Printing Notes (Michael Gray Workshop @ CCP, 1998 or 1999)

1. Soak paper in salt solution for 2-3 minutes.

– 1 liter distilled water
– 20 gm Ammonium Chloride
– 20 gm Sodium Citrate

2. Sensitize salted paper with 12% Silver Nitrate.

– 100 ml distilled water
– 12 gm Silver Nitrate

3. Coat with glass rod using approximately 2ml per 8×10.

4. Expose to ultraviolet light

Print out should look well over-exposed, it will lighten considerably.

5. Rinse up to 10 minutes in running water

6. Tone (optional)

Gold
– 1 liter water @ 100°F
– 6 gm borax
– 12 ml 1% gold chloride
tone for 3-10 minutes

Palladium
– 1 liter water
– 4 ml Pd solution (15%)
– 5 gm citric acid
– 5 gm sodium chloride
tone for 3-10 minutes

Platinum
– 1 liter water
– 2 ml Pt solution (20%)
– 5 gm citric acid
– 5 gm sodium chloride
tone for 3-10 minutes

Selenium
– 1 liter water
– 3 ml KRST (Kodak Rapid Selenium Toner)
tone for about 1 minute

7. Wash 3-5 minutes in running water

8. Fix in 10% sodium thiosulfate – 2 baths 4 minutes each
– 1 liter water @ 90°F
– 100 gm sodium thiosulfate

9. Wash 3-5 minutes in running water

10. Hypo clear
– Kodak HCA or
– 1% sodium sulfite for 2-4 minutes

11. Final wash 20-30 minutes


Here is a link to a pdf scan of Michael Gray’s pamphlet The Art Of Photogenic Drawing.

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