Looking for KCN

[koraks]

When we do bleaching of cyanotypes with an alkali, the highlights start disappearing quite rapidly while the shadows lag behind significantly

Yes, as you'd expect.
I appreciate your explanation, but will keep my response at this for now because we're drifting off topic quite badly, as you also noted. It's interesting material and tempting to do some experiments, but I'm working on other things right now. We'll have to revisit this at some point!

 

[Two23]

I've been doing wet plate almost weekly for the past three years. I have some thoughts. I've been using ammonium thiosulfate 1:3 for the past two of the three years. It seems to work well and is fairly quick. I'd like to try some KCN but for reasons no one has mentioned. It's far more water soluble than ammonium thiosulfate or "hypo." Most of the time this isn't an issue for me as I give my plates a quick rinse, keep them wet, and take them home for a complete rinsing. Ammonium thiosulfate is a bit stubborn to get out of the emulsion and like any fixer you can't just leave some of it. KCN being very soluble takes far less water to completely rinse out and that's a HUGE issue when I'm shooting at an event one plate after another. With am-thio I have to put the completed tins into a holding tank, take them home to rinse and dry. With KCN I could rinse them well enough there, dry, and varnish. The photos could be ready for take home in an hour or so. If you're working in a studio this isn't so much an issue but if out on location it becomes a big headache. I have yet to be at a location where I had running water available or even large quantities for washing a dozen or two plates.


Kent in SD

 

[AgX]

The same time one would not want a KCN solution at such an outdoor event.

 

[Two23]

The same time one would not want a KCN solution at such an outdoor event.

I would not take the powder/pure form of course. Highly diluted as a fixer it should be no more dangerous than my silver nitrate or developer laden with acetic acid which can burn. Wondering if you do wet plate yourself and am familiar with it?


Kent in SD

 

[nmp]

I've been doing wet plate almost weekly for the past three years. I have some thoughts. I've been using ammonium thiosulfate 1:3 for the past two of the three years. It seems to work well and is fairly quick. I'd like to try some KCN but for reasons no one has mentioned. It's far more water soluble than ammonium thiosulfate or "hypo." Most of the time this isn't an issue for me as I give my plates a quick rinse, keep them wet, and take them home for a complete rinsing. Ammonium thiosulfate is a bit stubborn to get out of the emulsion and like any fixer you can't just leave some of it. KCN being very soluble takes far less water to completely rinse out and that's a HUGE issue when I'm shooting at an event one plate after another. With am-thio I have to put the completed tins into a holding tank, take them home to rinse and dry. With KCN I could rinse them well enough there, dry, and varnish. The photos could be ready for take home in an hour or so. If you're working in a studio this isn't so much an issue but if out on location it becomes a big headache. I have yet to be at a location where I had running water available or even large quantities for washing a dozen or two plates.


Kent in SD
View attachment 314659

That seems like a practical benefit of using KCN - however, if you look at the solubility of the 2 fixers, that of ammonium thiosulfate is actually higher (by nearly 2.5X) than KCN. So the solubility is not probably reason for KCN being more effectively washed out of the collodion. I wonder if the phenomenon that occurs in the traditional silver gelatin, i.e. bonding of the thiosulfate ions to the gelatin and the cellulose of the paper which then takes much longer to clear out, is also behind here. Of course, this is more prominent in the case of sodium than the ammonium thiosulfate. The remedy in that case has been the use of hypoclear agent (basically sodium sulfite) which reduces the washing time significantly. It could be that thiosulfate in wet plate also attaches itself to the collodion (which is afterall nitro-cellulose.) Has there been any attempt at using hypoclear agent for wet plate?


:Niranjan.

 

[Two23]

That seems like a practical benefit of using KCN - however, if you look at the solubility of the 2 fixers, that of ammonium thiosulfate is actually higher (by nearly 2.5X) than KCN. So the solubility is not probably reason for KCN being more effectively washed out of the collodion. I wonder if the phenomenon that occurs in the traditional silver gelatin, i.e. bonding of the thiosulfate ions to the gelatin and the cellulose of the paper which then takes much longer to clear out, is also behind here. Of course, this is more prominent in the case of sodium than the ammonium thiosulfate. The remedy in that case has been the use of hypoclear agent (basically sodium sulfite) which reduces the washing time significantly. It could be that thiosulfate in wet plate also attaches itself to the collodion (which is afterall nitro-cellulose.) Has there been any attempt at using hypoclear agent for wet plate?


:Niranjan.

Yes, it does attach to the collodion from what the guys who regularly do reenactments tell me. I have bought some hypoclear to experiment with.


Kent in SD

 

[AgX]

I would not take the powder/pure form of course. Highly diluted as a fixer it should be no more dangerous than my silver nitrate or developer laden with acetic acid which can burn. Wondering if you do wet plate yourself and am familiar with it?

I made my remark to be on the safe side, as there only are ambiguous reports on transdermal poisoning with KCN solutions. But as said one can control ones stuff much better in a studio/lab surrounding than being mobile on such events.

 

[TheFlyingCamera]

There's a chemical supply place down in Richmond, Virginia (whose name escapes me at the moment) who would sell wet-plate chemistry to folks looking to buy stuff in non-industrial quantities (I got my glacial acetic acid and some of the other nasties from them). For the nasty stuff you had to fill out an FBI form to validate you were not buying it for nasty purposes. I should still have some of the bottles down in my chemical store - I'll look up the name later today and post it here.

 

[RBarr]

In America and developed democracies, I think you will not be able to get that..
This is the price of urbanization, environmental conditions, and so on.
Available in Egypt, my country sells by kilo.
But despite that, I didn't like to use KCN,, for bleaching. It's a relatively expensive ingredient (from my point of view).
Therefore, I was able to find very suitable and very affordable alternatives.
So, I advise you to tell us what you want to do with (KCN) >>>> Maybe we can suggest you a suitable alternative that you didn't think of.

I prefer it as a fixer for tintypes and ambrotypes. I have other fixers and use them regularly, but prefer the KCN for certain applications. I have a jar left so I will have the ability to fix quite a few plates - just wanted a source for more for when the supply runs out. I do work at large industrial sites with in house labs and will try those as well.

 

[RBarr]

There's a chemical supply place down in Richmond, Virginia (whose name escapes me at the moment) who would sell wet-plate chemistry to folks looking to buy stuff in non-industrial quantities (I got my glacial acetic acid and some of the other nasties from them). For the nasty stuff you had to fill out an FBI form to validate you were not buying it for nasty purposes. I should still have some of the bottles down in my chemical store - I'll look up the name later today and post it here.

I'd take any info you feel comfortable passing on.

 

[RBarr]

Thank you all for the insightful replies. As for the toxic nature of the KCN - I treat all of the chemicals the same in the field. I have the facilities to handle, mix and dispose of all of them in accordance with all the applicable regs. My company is on projects currently decommissioning large industrial (brownfield) facilities in NYS and I will have access to all of the abandoned lab buildings. Maybe I will find more just like I found the jar that I have now! Thanks again everyone.

 

[StrangestStranger]

https://www.grainger.com/product/SPECTRUM-Potassium-Cyanide-39G722

It's not cheap, but available. I don't know what hoops you need to jump through to order it, though.

 

[RBarr]

https://www.grainger.com/product/SPECTRUM-Potassium-Cyanide-39G722

It's not cheap, but available. I don't know what hoops you need to jump through to order it, though.

Looks like a good place to start. I have an account there too. Thank you.