salt prints - coating fixing & role of citric acid

[pdeeh]

This is turning into an excellent thread on salted paper technique rather than the original topic I posted about, which was strictly to do with Citric acid.
WOnder if it's worth asking a modmin to either split it off the most recent posts to a new thread or to retitle it?

 

[Herzeleid]

This is turning into an excellent thread on salted paper technique rather than the original topic I posted about, which was strictly to do with Citric acid.
WOnder if it's worth asking a modmin to either split it off the most recent posts to a new thread or to retitle it?

I might have hijacked the thread sorry But, Ned mentioned the fog.
Ned did extensive testing on salted papers fogging in an earlier thread.
May be we can collect them under one thread.

 

[pdeeh]

No need to be sorry, it's just that it makes good info harder to find if someone is searching for salt print info - who'd look at a thread about citric acid if they wanted to know about coating and fixing for instance?

I've asked for it to be split or retitled, probably the latter as I've been told in the past splitting threads is a pita for the modmins.

 

[pdeeh]

May be we can collect them under one thread

Mega threads can be more trouble than they're worth I think (eg the xray film thread at lfpf, it's nearly 500pages and 5000 posts long now, and contains all the info you might ever need - none of which is easily found)
It's sometimes better to have shorter threads on a cluster of related subjects than try and encompass all.
(when there's a debate on apug about resurrecting old threads vs starting new ones, this is often overlooked by those strongly in favour of the former)

 

[NedL]

I think the title change was a good idea and apologize for taking the thread off topic.

And I think eventually a thread specific to citric acid or the role of citrate and/or ammonium would be interesting. I've seen writing suggesting that using citric acid or using citrate salts is equivalent, but I don't think that's true ( they produce salt prints with different colors! ) and I don't think they restrain fog in the same way. So perhaps we can start another more specific thread sometime.

I need more hypo anyway, so today I'm adding ammonium chloride to the order so I can try Serdar's wash/fix method.

 

[nmp]

I think the title change was a good idea and apologize for taking the thread off topic.

And I think eventually a thread specific to citric acid or the role of citrate and/or ammonium would be interesting. I've seen writing suggesting that using citric acid or using citrate salts is equivalent, but I don't think that's true ( they produce salt prints with different colors! ) and I don't think they restrain fog in the same way. So perhaps we can start another more specific thread sometime.

I need more hypo anyway, so today I'm adding ammonium chloride to the order so I can try Serdar's wash/fix method.

Ned:

If I remember/understand correctly, citrate actually acts like a halide salt and forms photoactive compound with the silver nitrate where as citric acid is more of a restrainer that delays/slows the onset of the silver halide dissociation.

 

[NedL]

I've ordered some ammonium chloride so that I can try Serdar's wash sequence. Also some glycerin, because it made me curious. Also some thiourea so that I can try this kind of toning after fixing.

To me it seems like the very first step in the wash sequence is very important, to remove as much of the excess AgNO3 as possible. Maybe your tap water has enough chlorine in it so that it is being removed by precipitating insoluble silver salts, but AgNO3 is soluble and I think a lot of it might be washed out just by dissolving and by dilution. I'll try the simplest approach for me first: our "tap water" is RO-filtered well water and has no chlorides and very few dissolved solids of any kind. If it does not work, I will try to emulate Serdar's tap water and add a tiny amount of chlorine.

This is just one example of how the details are different for every salt printer, and we might not even know which ones are important. It's why generalizations in "alt" processes aren't very good. Often something that works for one person works differently for another, and there are too many variables to guess why. I know that I need to start paying attention to humidity.... at least make a note about it when I print.

For the final wash, I don't think I'll change my habit of "at least one hour, and preferably longer".
Will report back with results....eventually

 

[removed account4]

fantastic thread !

 

[Herzeleid]

I've ordered some ammonium chloride so that I can try Serdar's wash sequence. Also some glycerin, because it made me curious. Also some thiourea so that I can try this kind of toning after fixing.

To me it seems like the very first step in the wash sequence is very important, to remove as much of the excess AgNO3 as possible. Maybe your tap water has enough chlorine in it so that it is being removed by precipitating insoluble silver salts, but AgNO3 is soluble and I think a lot of it might be washed out just by dissolving and by dilution. I'll try the simplest approach for me first: our "tap water" is RO-filtered well water and has no chlorides and very few dissolved solids of any kind. If it does not work, I will try to emulate Serdar's tap water and add a tiny amount of chlorine.

This is just one example of how the details are different for every salt printer, and we might not even know which ones are important. It's why generalizations in "alt" processes aren't very good. Often something that works for one person works differently for another, and there are too many variables to guess why. I know that I need to start paying attention to humidity.... at least make a note about it when I print.

For the final wash, I don't think I'll change my habit of "at least one hour, and preferably longer".
Will report back with results....eventually

Ned, I am eagerly waiting for your results. I plan to test tapioca starch sometime, the results with arrowroot would be very informative. (I think rice starch is the best in terms of conservation, I have to check that info)

I agree during the tests initial wash (almost as long as 15mins) made the greatest change. Especially when troubleshooting after a workshop, most of the problems can be attributed to inadequate initial wash. Too cold tap water also is also a problem. First few minutes few changes of water let the silver nitrate and chlorides wash away, then left in water for 10mins face down. Your RO-water might be too soft but if it is not RO-distilled water it will still have some ions in it. I wouldn't worry about it, but adding a pinch of table salt won't hurt.

Thanks to Loris Medici, I made a habit of checking RH. This table is also informative http://www.tis-gdv.de/tis_e/misc/klima.htm

Good luck

P.S. Glycerin is another interesting additive, needs discussion in depth.

 

[NedL]

Reverse osmosis filtered, but not distilled. I think you are right there will still be some ions. I will pay careful attention to water temperature.
And different starches also need discussion in depth! I am going to try rice starch with my next batch of calotypes, but I also want to try it with salt prints. Thanks!