Question regarding Selenium

[RmFrase]

I've started making my own enlargements and am surprisingly getting pretty good. I've starting toning my prints after obtaining multiple bottles from friends who have given up analog for digital. I've mixed the Selenium with a ratio of 1:19. After a few days, I go to tone more prints and I see a dark sediment like substance at the bottom of the Selenium mix.

I've searched online, but can't find any explanation for this. Any thoughts?

Thanks.

[neil poulsen]

Is this 1:19 with water? Some mix it with hypo clearing solution.

[RmFrase]

Yes with water. I have heard about HYPO CS, but also heard that it is not a requirement. The directions do state mix with water.

[Michael Clark]

If you are using unfiltered tap water it could be some impurity's that the selenium are reacting too, running the toning bath throw a coffee filter will clean it up. I use distilled water only because of the hardness of the water here.

Mike

[chuck461]

This happens with mine also. It seems to be common. I can't remember hearing an answer to what the precipitate is, but I think most people just use a coffee filter to get rid of it without any apparent problems.
Another tip: Many people never throw out their Selenium toner. Just add more stock to the working solution, when it gets too weak.

Chuck

[RmFrase]

Chuck, did you use unfiltered tap water, or distilled?

[chuck461]

I mix with unfiltered tap water.

Chuck

[Peter Lewin]

Two comments on prior posts: (1) I was always taught to keep the selenium toner separate from the hypo-clear, because the toner lasts pretty much indefinitely, while the hypo-clear has a relatively short life. So I tone in a tray of KRS, and then pass the toned prints into a tray of hypo-clear. The KRS goes back into the storage bottle, the hypo-clear is discarded. (2) I used to get the black deposits, but I made two changes when I mixed up my last batch of KRS more than a year ago: I mixed up 2 liters worth at about 1:20 with distilled water, and now whenever I'm done toning, I run it from the tray through a paper coffee filter and funnel back into the storage bottle. No more deposits. And as has been mentioned, when the toning becomes noticeably slower, I just add some fresh KRS.

[Toyon]

I've never had a Selenium solution that didn't develop weird crap over time. You can filter it, but that doesn't really solve the problem for long. Ideally, one would use the substance until exhaustion, as that ensures that the Selenium won't go into the waste stream. An alternative is to change the Selenium when it gets crapped up, store it in a bucket to encourage evaporation of the water, and save the residue for hazardous waste collection day.

[Will S]

Everyone knows to wear gloves with selenium toner (liquid) right? And it can give off ammonia as well so needs adequate ventilation. Nasty stuff. Oh - the precipitate is normal and (I think) from using an acid stop and acid fix.

[Toyon]

Everyone knows to wear gloves with selenium toner (liquid) right? And it can give off ammonia as well so needs adequate ventilation. Nasty stuff. Oh - the precipitate is normal and (I think) from using an acid stop and acid fix.

I use an alkaline fix.

[RmFrase]

Yes, I use gloves. And the I use an acid Stop Bath. Fixer is plain Hypo.

[RmFrase]

Thank you all for your responses. Greatly appreciated.