Removing Silver

[peeniwali]

Hello all,

I have a project where I am looking to remove all of the metallic silver. Basically I am trying to strip it bare so there is no image at all except where I mask it off.

I was thinking that Farmers reducer or potassium ferricyanide + fixer might do that. I am open to thoughts on this and would love some feedback. Although I would prefer to do this in a single bath I could do it with 2 and that would be just fine.

If I do use potassium ferricyanide can I add that directly to the fixer or do I have to keep the 2 chemicals separate? For some reason I am thinking Farmers reducer is a mix of the two but I am not sure.

Cheers,

Peeniwali

[holmburgers]

Farmer's reducer is hypo and K-ferricyanide, and that should work. A potassium-dichromate bleach or potassium-permanganate bleach should work as wel, as per reveral processes.

[Mike Wilde]

Film or paper? Ammonia will strip the gelatin layer off pretty quick in my experience. I use this technique occasionally to take dud test prints on papers that I otherwise like the texture of. I then re-coat them for cyanotype prints.

[peeniwali]

Mike,

Its on nylon fabric, no gelatin, just silver.

-Peeniwali

[Mike Wilde]

Look up tray cleaner formulae- they are usally a mix of an oxidizer and a strong acid of one sort or other, as discussed in this thread. If we are trying to take silver (stains?) off of fabric the acid may atack the nylon first!

[Ian Grant]

Iodine in Potassium Iodide solution is the best clean working silver bleach. It's the only one that leaves no trace stains.

Ian

[Gerald C Koch]

A mixture of potassium ferricyanide and hypo is unstable. They must be mixed just before use.

[CBG]

Iodine in Potassium Iodide solution is the best clean working silver bleach. It's the only one that leaves no trace stains.

Ian

I have a few references to formulae for iodide bleaches. One, the simplest, being:

Pot Iodide 15% solution
Iodine 5% solution

This is diluted 1 to 64 for use.

Would this be what you are referring to? And is it a rehalogenating bleach?

[Ian Grant]

That's about right. I use teh Iford formula.

No it's not rehalogenating because of the Iodine, Used too strong it can leave a stain in Gelatin, I found after fixing this goes completely with a quick dip in old dev.

Ian

[peeniwali]

All good comments and really appreciated. I need to see what is compatible with the nylon substrate I am using and get going on some test strips.

-Peeniwali