Capacity of selenium toner

henpe · Jan 27, 2020

I have been toning a fair amount of prints in selenium toner without really paying attention to toner capacity, until now. I have now made some calculations (see below), which indicate that 1 litre of working solution at strength 1+19 is only good for two prints at 12x16"...a surprisingly low number I must say...somthing must be "wrong" in my assumptions??!!

In my (perhaps limited) experience, it is possible to more prints than indicated above, but when toning for increased D-max I actually find it quite hard to judge when toning is actually effective or not (even if sticking to the practice of having a wet print as reference). In an attempt to inform myself on the capacity of selenium at weaker strengths I have searched on Photrio, and also elsewhere on internet, but without any informative hits. The lack of information made me write this post and ask...

What is the common understanding on the capacity of selenium toners at higher dilutions? Anyone who can provide some insights?

Best regards
Henrik

Calculations:
Inspecting datasheets by Kodak, Ilford and Fotolabor (makers of LP Selenia, Rollei Selenia, etc) they all seem to agree that 1 liter of *working solution* at strength 1+3 should be good for 25 sheets of 8x10".

Given the information above I deduce that 1 liter of *concentrate* is is good for 4*25=100 pcs of 8x10, or equivalently 8000 sq inch, right? I normally print on 12x16" (equals 192 sq. inch) paper and tone in selenium at strength 1+19. Continuing on my calculations, I deduce that 1 litre of *concentrate* should be sufficient for approx 42 sheets of 12x16" (8000 / 192 = 41.67). Following my reasoning, this imply that 1 liter of working solution at strength 1+19 is only good for 2 prints of size 12x16"

Doremus Scudder · Jan 27, 2020

I've addressed this often here and over at the LF Q&A forum. Search on my name and selenium toning for lots more info than you likely want.

I'll quickly address your issues:

First, if you see no change in the print, i.e., no change in D-max or no change in image color, toning is not occurring. It's that simple. Some papers don't tone at all in selenium or only with a rather strong solution. Some papers change color rapidly in a very weak solution. To repeat, however: no change = no toning happening.

As far as capacity goes: the more you tone your prints, the more active toner you use up. If you have a lot of prints with a lot of dark areas and you want a lot of image-color change, you're going to use the toner a lot faster than if you have a lot of light prints and just want a slight change in image color. Manufacturers' capacity recommendations are based on some arbitrary amount of toning and some arbitrary tolerance for toning times (as well as hidden profit motives). Using them religiously would result in lots of active selenium getting tossed down the drain (as you can see from your calculations - toner will last a lot longer than that before anything has to be done). Selenium is a heavy metal and a pollutant. I find the recommendations to discard active solutions pretty irresponsible. Kodak used to recommend mixing the toner with Hypo-Clearing Agent and then tossing the whole bath when the capacity of the Hypo Clear had been reached. Really irresponsible. There is a better way...

My most important point: You never have to discard your selenium toner. Just filter and replenish and use it indefinitely. I have two gallons of selenium toner, one "strong" and one "weak" that I have been using this way for way more than 10 years. Just toned a batch of prints the day before yesterday. The toner worked just great. Replenishing and re-using the toner is more economical and more environmentally responsible. See below for more details.

The "toning for permanence" myth: Yes, selenium toner will protect the silver in your print if it gets toned. Unless toned to completion, total protection is not achieved. Few of us want a bright red or totally selenium reddish-brown print, so we just tone partially. The degree of protection is proportional to the degree of toning. I tone to just a hint of image-color change and an increase in D-max (for those papers that tone that way). The protection is minimal. I tone because I like the effect, not to protect the print. Those that drag their prints quickly through a weak selenium solution thinking to protect them are not getting what they expect. Better to concentrate on proper fixation and washing (use the ST-1 or the selenium toner test for residual silver and the HT-2 test for retained hypo to check your work-flow).

My advice:

Tone visually. Keep an untoned print nearby for comparison. Pull the print from the toner a bit before it gets to the point you want it (you can always return it to the toner for more toning, but not vice-versa!). If you see no change, then there's no toning happening. If you don't want any change in image tone, don't bother toning; you're not protecting your print, just wasting time. Furthermore, the practice of toning for a given time at a given dilution to achieve a given result is just wrong. Every print that goes through the toner used up some of the available selenium and weakens it. In order for print five to be toned to the same extent as print one, more time will be needed (that is, if you're using an appropriate amount of toner in a tray sized for the size of prints you're toning, e.g., one liter in an 8x10-inch tray). Plus, different images want different amounts of toning. A high-key print will almost always need a different toning time to suit the image than a heavy print with lots of dark areas. Visual evaluation by the artistic eye is the only way to deal with this.

Keep your toning solution and re-use it. When toning times get too long, just add some concentrate. You can be as precise about this as you like; I just add a splash of concentrate when times get too long, erring on the side of not enough. If the times don't come up to short enough, I'll add a bit more. Before and after use, filter your toner through a coffee filter or the like. Lab filters are great and do a better job, but good old #4 cone-shaped coffee filters in a funnel have worked well for me for years. The toner will throw some black precipitate (flakes and fine particles) with extended use. These filter out and the toner is as good as new. Build-up of by-products does not seem to be a problem (I think filtering the precipitate removes them). I test my prints regularly with the tests mentioned above. Never a problem.

Hope this helps,

Doremus

henpe · Jan 27, 2020

Doremus,
Thanks for sharing and for the advice. I have actually read your posts on Photrio many times before and have just recently started to follow the workflow you suggests; to not discard but to replenish the toner seems sound and rational.

Just to clarify a bit on my original post. I do not wish to tone for permanence, but rather for an increase in D-max. When the prints are wet, however, I sometimes find it quite tricky to see when the increase i D-max "kicks in". Consequently, it is also a bit tricky to judge when you need to replenish. If I should trust my calculations, I should be aware and look for signs of toner exhaustion for every second print or so, and be prepared to replenish quite frequently....

Thanks again Doremus for your reply, it is a very informative summary!

Doremus Scudder · Jan 28, 2020

Henpe,

A couple of observations:

First, the manufacturers' capacity recommendations for selenium toner working solutions are based on significantly more toning than you will be doing just to increase D-max, so you won't have to be worrying about significantly different results every two prints. More like every 10-20. And, the effect of weakening toner is just a gradual change in toning time. After 10 prints, you may just be toning for some seconds or a minute longer to get the same result. Visual evaluation of the toning takes this all into account. (I do keep an eye on toning time, just so I can give exactly the same time to a subsequent print or two; I'd never try to do more than a few at the same toning time). When to replenish is totally up to your preference for toning time. I like three-four minutes, some like longer. The faster the toning, however, the less time you have to evaluate and decide when to pull the print, so aim for a longish, comfortable toning time to start.

Second, not every paper shows a substantial change in D-max when toning, and most don't show any before the image tone starts to change. The (sometimes really gratifying) change in contrast happens as the image tone is changing. Adox MC-110 performs nicely this way for me, but best increase in D-max happens with strong magenta filtration (I guess the softer components of the emulsion don't tone the same as the higher-contrast component). And, there is a marked, but IMO, not too obtrusive change in image tone. I like a bit of eggplant-hue, or cool brown for my prints. Slavich Unibrom 160 papers turn brown before much increase in D-max occurs and need to be toned carefully if you want to keep the image tone from running away toward brown (yep, I still have a stash - I'd love to find more somewhere). And, toning characteristics are slightly different from grade to grade. Foma 111 papers tone fairly quickly and show a slight change in D-max with just a bit of toning, but there is also some color change before the D-max really increases.

In short, I don't think you are going to get a significant increase in D-max without some change in tone. However, Ilford papers may tone differently than the ones I tend to use most. I haven't used the Ilford Multigrade papers for a long time.

Some tips to help you better recognize the changes: Use the brightest light source you can and close up to examine the darkest areas of your prints for change. Using the usual recommendations for viewing light is not really strong enough to see subtle changes in the darkest areas. Don't use the bright light to evaluate your print tonalities overall though, just to "look into the shadows" better; the brightness moves the dark areas up into the more sensitive part of our vision.

Keep an untoned print in a tray of water right next to the toning tray and compare the same dark areas in the two prints, looking first at one, then the other and then away at something distant for five seconds or so, then repeat. You should be able to notice pretty easily when a change starts happening. Be aware that the first thing you may see is a change in image tone, so keep an eye on the mids and highlights too if you want to avoid a strong tonal shift as the color change happens first in the higher values with some papers. Keep in mind that you may not be able to get an increase in D-max without a shift in tone, or at all depending on your paper.

Use a neutral-colored tray, and the same color for both prints. Red trays give the print a reddish look to start with due to the reflection, so don't use red when toning red (selenium is basically red) or you'll get fooled by the tinge from the reflection. White is okay, but I prefer a neutral grey tray for toning (Paterson makes or use to make them; I've got a couple. White is my second choice).

Remember: If you can't see any change, nothing is happening. What changes first, however, is not always (maybe only rarely) D-max.

Hope this helps,

Doremus

jvonoldershausen · Jan 21, 2021

Hi Doremus,

I stumbled on this post of yours and had a question regarding the black precipitate that forms in selenium toner. I have a 2 gallon jug (1+19 initial dilution) w/ float that was mixed early last year. I haven’t toned often, today I did a session and afterward I poured the toner from tray back to into the jug. I hadn’t looked in there previously but immediately noticed many black strands floating in the selenium. Picture is attached!

Is this what you were referring to? Strangely I didn’t see any in the tray while toning, only after pouring back into the main jug...I’m assuming it was settled at the bottom and therefore didn’t come through the spout.

-Justin

Doremus Scudder said:
I've addressed this often here and over at the LF Q&A forum. Search on my name and selenium toning for lots more info than you likely want.

I'll quickly address your issues:

First, if you see no change in the print, i.e., no change in D-max or no change in image color, toning is not occurring. It's that simple. Some papers don't tone at all in selenium or only with a rather strong solution. Some papers change color rapidly in a very weak solution. To repeat, however: no change = no toning happening.

As far as capacity goes: the more you tone your prints, the more active toner you use up. If you have a lot of prints with a lot of dark areas and you want a lot of image-color change, you're going to use the toner a lot faster than if you have a lot of light prints and just want a slight change in image color. Manufacturers' capacity recommendations are based on some arbitrary amount of toning and some arbitrary tolerance for toning times (as well as hidden profit motives). Using them religiously would result in lots of active selenium getting tossed down the drain (as you can see from your calculations - toner will last a lot longer than that before anything has to be done). Selenium is a heavy metal and a pollutant. I find the recommendations to discard active solutions pretty irresponsible. Kodak used to recommend mixing the toner with Hypo-Clearing Agent and then tossing the whole bath when the capacity of the Hypo Clear had been reached. Really irresponsible. There is a better way...

My most important point: You never have to discard your selenium toner. Just filter and replenish and use it indefinitely. I have two gallons of selenium toner, one "strong" and one "weak" that I have been using this way for way more than 10 years. Just toned a batch of prints the day before yesterday. The toner worked just great. Replenishing and re-using the toner is more economical and more environmentally responsible. See below for more details.

The "toning for permanence" myth: Yes, selenium toner will protect the silver in your print if it gets toned. Unless toned to completion, total protection is not achieved. Few of us want a bright red or totally selenium reddish-brown print, so we just tone partially. The degree of protection is proportional to the degree of toning. I tone to just a hint of image-color change and an increase in D-max (for those papers that tone that way). The protection is minimal. I tone because I like the effect, not to protect the print. Those that drag their prints quickly through a weak selenium solution thinking to protect them are not getting what they expect. Better to concentrate on proper fixation and washing (use the ST-1 or the selenium toner test for residual silver and the HT-2 test for retained hypo to check your work-flow).

My advice:

Tone visually. Keep an untoned print nearby for comparison. Pull the print from the toner a bit before it gets to the point you want it (you can always return it to the toner for more toning, but not vice-versa!). If you see no change, then there's no toning happening. If you don't want any change in image tone, don't bother toning; you're not protecting your print, just wasting time. Furthermore, the practice of toning for a given time at a given dilution to achieve a given result is just wrong. Every print that goes through the toner used up some of the available selenium and weakens it. In order for print five to be toned to the same extent as print one, more time will be needed (that is, if you're using an appropriate amount of toner in a tray sized for the size of prints you're toning, e.g., one liter in an 8x10-inch tray). Plus, different images want different amounts of toning. A high-key print will almost always need a different toning time to suit the image than a heavy print with lots of dark areas. Visual evaluation by the artistic eye is the only way to deal with this.

Keep your toning solution and re-use it. When toning times get too long, just add some concentrate. You can be as precise about this as you like; I just add a splash of concentrate when times get too long, erring on the side of not enough. If the times don't come up to short enough, I'll add a bit more. Before and after use, filter your toner through a coffee filter or the like. Lab filters are great and do a better job, but good old #4 cone-shaped coffee filters in a funnel have worked well for me for years. The toner will throw some black precipitate (flakes and fine particles) with extended use. These filter out and the toner is as good as new. Build-up of by-products does not seem to be a problem (I think filtering the precipitate removes them). I test my prints regularly with the tests mentioned above. Never a problem.

Hope this helps,

Doremus

Doremus Scudder · Jan 21, 2021

Justin,

Two things could be happening.

First, if you're replenishing and reusing your toner, there will be a black precipitate that you need to filter out. I filter my toner before and after each toning session.

The fact that you have strings leads me to believe that you may have some slime growing in your toner as well. I've had this happen once or twice in 25+ years. Just filter it as well; no worries.

Best,

Doremus

jvonoldershausen · Jan 21, 2021

Ok good to know Doremus! The few times I have toned since mixing this batch (maybe 3 sessions or about 20-30 prints total), the toner was poured back from tray to jug. I haven't replenished yet because its 2 gallons and i figured with so few sessions it most likely hasn't depleted much. My toning times were between 2-4 minutes today for reference.

Might it be better for the selenium to be stored in a bottle with screw top vs a jug w/ float? Maybe that is contributing to the production of this precipitate or possible slime

Doremus Scudder said:
Justin,

Two things could be happening.

First, if you're replenishing and reusing your toner, there will be a black precipitate that you need to filter out. I filter my toner before and after each toning session.

The fact that you have strings leads me to believe that you may have some slime growing in your toner as well. I've had this happen once or twice in 25+ years. Just filter it as well; no worries.

Best,

Doremus

Doremus Scudder · Jan 24, 2021

I store my toner in jugs with screw-tops and usually fill them fully. Having a large surface exposed to air and without a cap might allow more spores to find their way into the solution... I don't have the slime problem any more; just once or twice way in the past.

Doremus

jvonoldershausen · Jan 27, 2021

Doremus Scudder said:
I store my toner in jugs with screw-tops and usually fill them fully. Having a large surface exposed to air and without a cap might allow more spores to find their way into the solution... I don't have the slime problem any more; just once or twice way in the past.

Doremus

Yea makes sense for something that isn't ever discarded. Thanks Doremus!

Capacity of selenium toner

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