So the results are quite opposite to Raghu's findings above on positive film. I guess perhaps there is a reason why there is almost no literature for indirect sulfide toning of salt prints, that I know of that is.
What is the image in a salt print made up of? Is it silver or some compound of silver?
It's metallic silver - just like a silver gelatin print. Particles are much smaller, hence the reddish color. Also they are sitting in the paper fibers as opposed to dispersed in a gelatin matrix - particularly when there is no external sizing such as gelatin or starch etc used - as is the case in my salt prints.
Could it be that the rehalogenating bleach acts like a blix on such very small silver particles and therefore removes most of them leaving behind only the bigger particles that are difficult to tone directly? Have you tried bleaching with a substantially more diluted bleach and for shorter duration of time? Just hazarding a layman guess on what might be taking place.
P.s. is your rehalogenating bleach Chloride based by any chance?
One other data point I have is that I have been able to regenerate the silver by redeveloping with a vitamin C developer, as I discussed in this thread (see step B to step C):
https://www.photrio.com/forum/threads/additive-prussian-blue-toning-of-silver-based-prints.177686/
There, in addition to silver, there was also ferric hydroxide present so it was not quantitative as to how much density got redeveloped back compared to what was there before. I guess I might have to do an experiment with only the salt print + bleach/re-halogenate + redevelop sequence.
I have seen your thread on additive toning before and I must say it left me highly impressed. Very nice work! I have something to add to the subject but that's for the distant future. Today I got hold of Keya brand pink salt as I was curious to find out how it fares as a toner. As before I attempted indirect toning of a scrap slide with the salt solution. Unfortunately, there was not any noticeable toning. I checked pH of the salt solution and it was between 6 and 7. So I added a little Sodium carbonate and tried toning again. Yet nothing much happened and I discarded the pink salt solution. Next I repeated the earlier experiment of using Keya brand black salt for indirect toning. pH of the salt solution was around 11 and I got nicely sepia toned slides in about a minute. So I guess pink salt isn't quite the same as black salt when it comes to toning, at least as far as Keya brand salts are concerned. Fortunately, pink salt tastes a lot better than the black one and I can put it to good use in the kitchen.
So it looks like the Himalayan pink salt, is mined from the salt caves in Himalayas and sold as is in either coarse or finely ground forms. In India, it is commonly known as Sendha used primarily in cuisine in lieu of table salt during religious festivals. I am guessing it does not smell sulfurous - it is mostly made of sodium chloride and some other minerals. I am not surprised that it did not produce any toning for you.
Thanks for the insight on the pink salt. The only reason I tested this salt was because the scientific analysis that I shared earlier in post #28 reported high amount of Sulphur in it. However, it's very much possible that the particular brand I used doesn't have sufficient amount of Sulfides to tone B&W film. As Kala Namak serves the purpose of toning, I'll continue to use it and not experiment with other brands of pink salt.
As can be seen, almost all of the density is back - there is slight diminishing but nothing compared to the loss of density in the case of indirectly toned sample (B in post #39.) More pronounced is the shift to more yellowish tone that might signify smaller grains as a result of the round trip. So it would seem not too much of the silver is lost during bleaching.
No idea. May be just not that active. I will use this other granular Kala Namak that looks like yours and see that makes a difference.Interesting! So what is going wrong with indirect toning?
I created a resource page for anyone who wants to try Kala Namak indirect toning on slides and silver gelatin prints.cc: @Ivo Stunga you might find the resource useful.
So I got the granular/coarse form of Kala Namak yesterday and I tried it out:
1) It seems more sulfurous based on the smell and the color, perhaps a tad bit faster, but by and large comparable from the direct toning perspective to the older powdery stuff I have.
2) pH is no different, still neutral so it seems the Keya one might be unique in that regard.
3) Indirect toning no different from before - so no improvement.
Here are couple of scans from the slides above:
EDIT: removed scans that showed the wrong color cast - massively different from what's projected.
Sorry for that, will do better.
If anyone would like to have anything moved from this thread to a new thread, please start the new thread and then give me instructions which posts you would like moved, and I'll have a go.
Even if we don't move any posts, it seems to me that a new thread on the subject of toned transparencies makes a lot of sense, even if it just refers to this thread, and then goes on from there.
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