What changes adding hypo clearing agent to selenium toner?

I know back in the day that it was common advice to mix selenium toner with hypo clearing agent or other wash aids, though I can't remember why. Seems these days the more common advice is to just mix your toner with water and use it to exhaustion.

I've been doing the latter for several years, any print I'm going to keep goes through KRST mixed 1:9 with plain old tap water. Works great.

Today I did something dumb, and when mixing up my jug of wash aid (I just use sodium sulfite, haven't bought actual hypo clearing agent in a long time), I accidentally dumped it into my selenium toner jug instead of my jug of water. Oops. It still toned my prints as normal. Have I somehow compromised my 1:9 KRST by adding all that sulfite, or should I just continue business as usual until I hit the exhaustion threshold where I would normally toss it and mix up new?

BHuij said:

I know back in the day that it was common advice to mix selenium toner with hypo clearing agent or other wash aids, though I can't remember why. Seems these days the more common advice is to just mix your toner with water and use it to exhaustion.

I've been doing the latter for several years, any print I'm going to keep goes through KRST mixed 1:9 with plain old tap water. Works great.

Today I did something dumb, and when mixing up my jug of wash aid (I just use sodium sulfite, haven't bought actual hypo clearing agent in a long time), I accidentally dumped it into my selenium toner jug instead of my jug of water. Oops. It still toned my prints as normal. Have I somehow compromised my 1:9 KRST by adding all that sulfite, or should I just continue business as usual until I hit the exhaustion threshold where I would normally toss it and mix up new?

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I formerly used Kodak Hypo Clearing Agent when mixing Se toner. I think I picked up the habit from Kodak and Ansel books in the 80's. It may be best practice, I don't know.
My current procedure is I use "film strength" fixer, fresh with constant agitation for about 90-120 seconds, rinse the print for 15-30 seconds in a tray of fresh water, then straight into the Kodak Rapid Selenium toner 1+3 (1 toner, 3 water), all at 68-75°F. Toning is to my liking but it's fast. Warm tone papers like Fomatone require more dilute toner to have more control of the Toning, but 1+3 works fine. After toning quick rinse then into fresh hypo clear 2-3 minutes with agitation. Then a couple minutes of fresh water gentle wash, then into archival washer.

Personal taste is (currently) using water alone to mix up the toner.

BHuij said:

Seems these days the more common advice is to just mix your toner with water and use it to exhaustion.

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@Doremus Scudder has posted about this many, many times and I recommend at least trying his approach, because it really does work: don't discard your selenium toner. Just replenish it from time to time.

I've never seen the need to mix it with anything other than tap water.

If your KRST works with the sulfite added, I wouldn't worry about it. It wouldn't surprise me if the regular formulation of the KRST concentrate already contains a good amount of sulfite. There's also some ammonium thiosulfate in it and if anything, the sulfite should help to avoid its decomposition.

I checked my memory and the art of photography and have found this:
Many photographers used to add HCA to their selenium toner, why exactly i'm not sure my guess would be for convenience. They would then throw away the toner when the HCA stopped working, which it does much more rapidly than selenium toner, Back in the day chemistry was cheap and environmental concerns were not known of so this wasn't seen as a problem. Now everyone i know off has switched to a seperate HCA bath (after toning) so they can use their selenium for longer. As for your situation, your selenium is usable but most likely not for as long as normal. Now i do wonder if you could extend that life by still using a secondary HCA bath or if the HCA also affects the toner itself...

Something related, does anybody know if it is necessary to wash prints before toning after they have been in a secondary fixing bath or if you can go straight from fix 2 to selenium toner? (so the process would be dev, stop, fix, holding bath and at the end of the day holding bath, fix 2, selenium toner, HCA and final wash)

DutchDarkroom said:

Something related, does anybody know if it is necessary to wash prints before toning after they have been in a secondary fixing bath or if you can go straight from fix 2 to selenium toner?

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Experiences vary and I think the ultimate conclusion is that it depends. In principle you should be able to go from fix straight to selenium toner, but I think there have been problems in particular with certain fixers (alkaline as I recall) when doing this. Personally I only tone after an initial wash of 10+ minutes, but this is also a practical choice since I can batch up my prints towards the end of the session and then tone everything in one go. Or even tone them on a next occasion after initial evaluation of the prints.

For me it would be more practical, although i could take prints from the holding bath into the fix and back into the holding bath and wash them for a bit. I currently use ilford rapid fixer which i is acidic (ph 5.0-5.5), kodak rapid selenium toner contains 25-30% ammonium thiosulphate so i can't imagine a little fixer on a print would significantly change this. Based on ammonium thiosulphate already being in the toner and if your recollection is correct most problems occuring with alkaline toners i would come to the conclusion that is has to be perfectly fine. However i have no experience with this and i wouldn't like to risk it.

I think the problems people have experience when going from fix straight to toner can be tracked to (1) remaining silver salts in the fixer reacting with the toner to form stain and/or (2) developer carry-over into the toning bath. IDK for sure which is the main culprit, only that a few people have (also recently) reported such problems.

DutchDarkroom said:

if your recollection is correct

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That's always the $1m question, haha! I do know for sure that we have seen reports of staining problems with selenium toner not too long ago on the forum, as well as people reporting that a fix-direct-to-toner workflow works just fine for them. I take from this that it's case-specific and that you need to be alert to any problems, and adjust your workflow on signs of staining.

I searched a bit more on this and experiences are very very mixed. What is reported most is going from an acidic fixer straight into selenium tends to leave stains, but it is also reported that ilford rapid fixer (which to my knowledge is acidic) works fine and is also called an alkaline fixer by some people on here. Unfortunately there is no final judgement in darkroom methods so i guess we will never know certainly. My theory (based on what others have also said) is that it might have to do with water quality and so results will vary. I might test going straight from fixer into selenium to see if i get stains since there are reports stains come quickly, not on a long term basis. Or i will just take a couple extra minutes to wash my prints and be certain i'm doing it right.

DutchDarkroom said:

My theory (based on what others have also said) is that it might have to do with water quality and so results will vary.

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That's exceedingly unlikely unless the water for some reason has extreme amounts of very uncommon contaminants in it. Within the normal range of tap water - no way it'll have enough buffering capacity to shift pH to whatever turns out to be problematic, and presence of calcium salts will also not be a problem (it may make photographic solutions cloudy, but won't stain paper or film). Excess iron in water can be a problem, but is uncommon in tap water because this is one of the compounds that's removed by default through aeration followed by flocculation.

Either way, processes with a a fairly rigorous rinse/wash between fixing and staining are unlikely to present a problem, while attempts to shorten the process are inherently more risky and may or may not work. I think that makes the choice a fairly easy one if you factor in the labor that goes into making a decent print.

You seem to know a hell of a lot about water! I wonder what may cause these differing results then. Anyway i agree that it's not worth the risk for most people and i'll figure out a way to wash prints between fixing and toning. Thanks for the help!