Bleaching Prints

[Ian Grant]

So you store it in 10% solution and then everytime you need to bleach you mix some of it to make a more dilute solution? The more dilute solution to you discard it after use or can it be saved for a prolonged time?

I have som very dilute solution I mixed a year ago and Im still using it. Is that a problem?

Most formulae suggest a 10% solution for storage, I do discard the 1% solution after use, but then I don't use excessive amounts.

If and when Ferricyanide decomposes it forms Prussian blue so starts to turn greenish, then blue, a 1% solution may keep OK for some time even when made up with tap water and there's a clear colour shift as it goes off.

Ian

 

[RalphLambrecht]

I keep 10% ferricyanide and 3.5% potassium bromide solutions on hand and mix equal amounts of them with differing amounts of water to make working solutions of a rehalogenating bleach. ...[/url]

What is the idea behind adding potassium bromide? Prevent fog?

 

[Ian Grant]

What is the idea behind adding potassium bromide? Prevent fog?

You quoted the answer

To make a re-halogenating bleach which is needed for indirect toning. With no Bromide (or chloride) you can't convert the silver to AgBr (or AgCl).

Ian

 

[fschifano]

So what happens if one were to use a chloride instead of a bromide for a re-halogenating bleach? Further, can one use sodium chloride as the chloride, and in what proportion? Some brands of Kosher salt sold in the US contains nothing but sodium chloride. though there are some brands that contain an agent, yellow prussiate of soda, to prevent caking. I suspect these brands are to be avoided if salt can be used in a re-halogenating bleach.

 

[Ian Grant]

Chloride gives a warmer (less red/more orange) colour with sulphide and thiourea toners than Bromide. The traces of Iodide in some table salt and the anti caking agents have no effect as the level is so low.

Agfa published 3 bleaches and 3 or 4 toners and final image tone/colour was varied depending on the combination used.

Ian

 

[fschifano]

Thank you, Ian. I think I'll give it a go if I can find the Agfa formulae.

 

[fschifano]

Found the formulae for Defender Varigram bleaches and toners here: http://silvergrain.org/Photo-Tech/toners.html

 

[Marco Buonocore]

Thanks for the information; great thread. I like the convenience of a 10% stock - I find it's easier to tweak the bleach to my taste. Using Ian Grant's suggested 3g Ferricyanide + 3g Pot. Bromide + 1L water yesterday, I found it to be too quick acting. To each their own, of course.

The Defender Varigram toner has always fascinated me - I think this winter I'll spend some time with it, trying to get it to look like Kodak Sepia. Thanks for the link, Frank!

 

[Bob Carnie]

Ok so yesterday I made a bunch of prints solarized and now I am bleaching them to lift the highlights.


Here is a quick observation now that I am ten prints into it.

A squeegee is very helpful and slow running water, I bought a whole range of brushes at home depot, and am using a pot ferr and pot bromide combo as Ian suggest, I am refiixing and hypo clear and wash before I get to the next stage.

By using the squeegee each time you use the brush, you can lay down bleach exactly where you want it without it running , I have the prints on a metal sheet propped up with a 2x4 one its end, the bleach stays there and is perfect for my application.

The angel of the metal is key as well the water should be slow running as not to move the bleach around or have the bleach fall vertically where one does not want it.

I feel great about this and hope it is the key for this project... time will tell.

 

[Doremus Scudder]

Bob,

I'm sure you probably know this, but make sure your brushes don't have metal ferrules. They contaminate the bleach and cause weird bleaching problems. I use Japanese calligraphy brushes (bamboo). I also use cotton swabs and sometimes a fine sponge cut into various shapes for tricky places.

I'd be careful of getting bleach on the metal plate as well. Mine is plex. And keep the bleach off the metal part of the squeegee too...

Best,

Doremus