salted paper and a problem with last wash

[stefano_ber]

Hi everyone! I'm making a series of prints and I have a problem right at the last final wash.
During this wash, after the passage in HCA, in the last wash the print progressively becomes darker and loses contrast. Could it be the reaction with the chlorine in the water? how can I solve this problem?
My work cycle is this. After exposure I wash the print in distilled water with 5% salt for 5 minutes, then another 5 minutes in running water, fixing 2 + 2 minutes, 1 minute in running water, HCA and final washing.
I have tried different sizing, changing the percentage of gelatine from 0 to 1.5%, but the problem is always there.
Thanks for any advice!

 

[NedL]

These kinds of problems can be frustrating and difficult to diagnose, and they can depend on things you might not be thinking about, for example how the paper is salted and how the AgNO3 is applied. Many times you will see advice in books or on forums where somebody says what works for them, but there are so many variables that no two people are ever doing exactly the same thing. By far the best thing is to figure out what works for you.

Paper is always one of the biggest variables. Most papers have both internal sizing and surface sizing ( before you put any gelatin on it yourself ). In some kinds of papers ( and also depending on how you apply the salting solution ) the salt can get underneath the surface sizing where it can be difficult to wash out once silver chloride is formed ( please note, that if you mix your gelatin and salt together, this problem can still happen ).

It's almost impossible to answer your question without knowing a lot more about your procedures, but here are a few things you can try. First of all, figure out a way to make small test prints quickly so that you don't waste a lot of time and materials on testing.... then, run a series of tests ( this does not need to be very time consuming or a lot of work! ):

1. Make sure to mask part of the sensitized paper during exposure so that you have an area on the paper that is supposed to be white.
2. If you can keep part of the paper un-sensitized that is also very helpful ( it's okay if it has salt, but no silver nitrate! ) This gives you real paper white to compare to.
3. Try starting your wash with a series of short quick washes ( 15 or 20 seconds ) in plain distilled water. You should be able to see the silver chloride precipitating and falling off the paper... the water may become milky. If you have a dark print that has been exposed all over, you might not see the milky precipitate, but salt prints always have excess silver nitrate, and that will dissolve in these first quick washes. Drain completely between each of these short washes. You don't need to use lots of distilled water for these, just enough to cover the print, agitate, and pour off. Some very experienced salt printers suggest that you do these quick washes with the print face down so that the precipitate does not end up on the paper -- I haven't found much difference, but as I mentioned, sometimes what matters for one person doesn't for another.
4. Then after these short washes, go ahead with a 3 minute soak in water with salt in it. You don't need 5%, even a pinch will do it at this point. The idea is to convert any remaining free silver nitrate to silver chloride that can be removed by the fixer.
5. Then 2x5 minute washes in plain water.
6. I don't know what kind of fixer you are using, or how strong it is, but I think 2 x 3 minutes is pretty close to the minimum. If there are problems with silver chloride forming underneath the surface sizing, this step needs to be longer!
7. Then another quick wash to remove excess fixer.
8. As for HCA, I think it's probably not a bad idea to have a 3 minute soak in weak ( 1 or 2% is fine ) sodium sulfite, and I usually do it, but I have to admit I haven't seen convincing evidence that it is really necessary.
9. Then the step that many people skip, which I think is really important: a long wash: an hour or more changing the water every 10 or 15 minutes.

If you are still having trouble after this, it might be time to try a different kind of paper. I've tried some kinds of papers that are just impossible ( the silver nitrate reacts with the internal sizing, making products inside the paper that can't be washed out and that darken over time.

Then, if all else fails, there are 2 more things you can try. But this is probably enough to give you some ideas of where to start. I'll try to come back later and add the 2 more "last resort" things you can try. Again, I strongly encourage you to figure out a way to make small quick test prints with un-sensitized areas and masked areas.. solving these kinds of things is much easier if it's not a lot of time and effort to try different things. It's also super handy if you want to see what different things do quickly ( for example, if you are toning your prints, the amount of gelatin changes how the results look... you can quickly try different combinations of gelatin and toner to see what they do and which ones you like best for your prints )

Good luck and I wish you success!

 

[NedL]

Okay as promised I'm back with 2 more.

This one really isn't "last resort". I have tested this method with several difficult papers and found that it works very well. I keep it in mind for "difficult' situations. It uses a strong ammonium chloride solution. Beware the ammonium chloride will dissolve a lot of silver chloride, and after it's been used the solution can stain ( fingers, clothing, sinks, etc ).. it should be disposed of the same way you dispose of used fixer. Please see post #23 in this thread. I think this is an excellent approach to fixing and washing a salted paper print.... one to fall back on if you are having problems.

I really do not think you will need this last one, but I'm putting it here because there are times it can be very useful:

This one really is a "last resort". I don't have my notes handy, so I can't attribute this to the person I learned it from, but it was a salt printer from 15 or 20 years ago. His process was very interesting. Sensitize your salted paper as usual ( salt, then silver nitrate )... then, right after the paper is sensitized, do a very complete washing before letting it dry. The idea is to wash everything that might cause trouble away, leaving only the paper and silver chloride. Then, before you expose the print, brush on a weak 1% or 2% (either is fine) solution of silver nitrate, let it dry, then print as usual. This process has an extra step ( the 1% silver nitrate, then dry the paper a 2nd time ), but it takes away most of the things that cause trouble ... strong silver nitrate solution reacting with things in the paper or sizing. When you use this process, you can even use a stronger silver nitrate during sensitization because the paper will be washed right after. Strong silver nitrate solutions often cause a lot of trouble that this process avoids. I have used this process when I had real problems ( with starch and arrowroot sizing, or papers that absorb too much salt, or that don't keep liquid on the surface for long enough. These can be very hard to work with ).

Also have fun!

 

[koraks]

During this wash, after the passage in HCA, in the last wash the print progressively becomes darker and loses contrast. Could it be the reaction with the chlorine in the water? how can I solve this problem?

The print becoming darker suggests fogging taking place. This implies that there is silver halide remaining in your print after rinsing, fixing and washing.
Your fixing regime seems quite minimal, depending on the kind of fixer you use. If it's rapid fixer, 2+2 minutes may *just* be enough, but it's on the short side. Especially with heavier papers, fixer does need some time to permeate the paper base and get at all the deeply embedded silver that is bound to be there. Keep in mind that with salted paper prints, the silver tends to permeate deeply in the paper base. In this sense the process is really different from silver gelatin, where the silver only is present in the thin gelatin emulsion. If you're using a non-rapid (e.g. plain hypo) fixer, 2+2 minutes is far too short. Use 5+5 minutes instead as a starting point.
If problems persist, try a different paper. Some papers work better than others and salted paper is a bit of a finicky process in this respect. Only with the right kind of paper, dmax is optimal and prints come out clean.
For what it's worth, I never use gelatin in my salted paper prints (I never found it gave any significant benefit) and neither do I use a HCA step. But I do wash prints I want to keep for at least 30 minutes after fixing, either with frequent water changes or in gently running water.
Overall, keep in mind that processing needs to be much more rigorous than with silver gelatin papers.

 

[stefano_ber]

Sorry for my translation!
Hello everyone! thanks for the replies! as regards the paper I mainly use Bergger cot320 and but I also used the Arches always 300gr. But I had the same problem in both cases. About fixer I use 10% sodium thiosulfate with 2/3% sodium carbonate. Sometimes I also use my own TF3 in 1: 4 solution. Regarding fixing, the problem is that there are conflicting opinions. Christopher James in his book says not to keep it more than a minute, 30 + 30 sec. Anderson talks about 4 + 4 with the TF4. Ellie Young always 4 + 4min. In any case yesterday I tried to extend the washing time (10 minutes more) and fixing to 5 + 5min and actually the result has improved. The print is considerably lighter and has more contrast. I would not want it to be just a case, so before I think I have solved it I would like to do more.
In transparency it looks clean, there is only a few black dots, but very rare and they are not present on the print, only in transparency. As far as gelatine is concerned, in fact, I do not see big differences, indeed with a lot of gelatin it is possible to sensitize only with flotation because the salt is more impermeable in the gelatin. In my opinion it might not be used, but it depends on the paper. If it is not already a paper one of its factory sizing it is better to put a minimum of it, so as not to sink the salt too much, giving less contrast and sharpness.

 

[koraks]

About fixer I use 10% sodium thiosulfate with 2/3% sodium carbonate. Sometimes I also use my own TF3 in 1: 4 solution.

Given the choice, I'd stick with TF3, since it's a rapid fixer. Sodium thiosulfate has no clear benefit IMO. Ammonium thiosulfate just does a better/quicker job.

In any case yesterday I tried to extend the washing time (10 minutes more) and fixing to 5 + 5min and actually the result has improved.

Sounds good! When you mention a wash that is extended by 10 minutes, do you mean the initial wash right after exposure and before fixing, or the final wash? What is the total washing time after fixing? Make sure it's sufficiently long - 30 minutes is the bare minimum in my experience. With heavier papers like the ones you use, I'd rather stick with at least an hour.

Do you mask the borders of your prints? If so, are they perfectly clear/white after processing? In my experience, this is the ONLY way to verify if your processing is good enough.

 

[stefano_ber]

no as washing I mean after exposure. I took a salt and citric acid bath for 5 minutes and then 15 minutes of running water(maybe is better add always some salts and acid citric or is enough simply running tap water). Then the fixer. With this process the print is decidedly cleaner.
Yes, in fact, I also prefer TF3 because it could then avoid the bath with sodium sulphite. However, In all the books talk about sodium thiosulfate and so I use it more often in order not to risk it. But the TF3 has never given me any particular problems.
The final wash takes about 30/40 minutes.
in the next days I will do other tests! thank you!

 

[koraks]

Hmm, I get good results with 2x 2minutes was after exposure in tap water with just a little citric acid added to it - only a pinch is sufficient. I don't add any salt is it didn't seem to have any benefit for me. A longer wash after exposure didn't seem to have any benefit in my processing. I don't think it hurts to use tap water after an initial rinse with slightly acidified water, but again, I didn't find it to be necessary to wash more than I outlined above.
I do use different papers than you, though. Specifically I get good results with a Dutch paper, Schut Simili Japon, I think it's 160gsm. I can't recall if I tried cot320 (I think I did, with somewhat inferior results to the Schut paper), but I'm fairly sure I never used Arches Platine. Anyway, trying some different papers, especially thinner ones than 300-320gsm, might help.

 

[stefano_ber]

Compared to before I increased the washing after exposure and fixer time, so I think that for 300gsm paper more time it is better. Perhaps your paper, being lighter, may take less time.
Moreover, papers like Bergger already have their own sizing, so I think it is more difficult to remove all residues.
Salt in the first wash in distilled water are recommended by many. In the books I have of James, Anderson say to put him in the first bath right away.
Honestly, I haven't tried to wash it initially with just tap water yet