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Moersch Bleach or Farmer's Reducer?

logan2z

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I want to experiment a bit with bleach in order to reduce density in areas of my prints, and there appears to be two primary choices:

1) A bleach like the one from Moersch which is a combination of Potassium Ferricyanide/Potassium Bromide

Moersch Bleach Concentrate - 100 ml

Moersch Bleach Concentrate - 100 ml - Bleach concentrate: ferricyanide/potassium bromideDilution: between 1+10 and 1+100
www.freestylephoto.com

2) Farmer's Reducer.

Formulary Spot Reducer II - 375 ml

Formulary Spot Reducer II - 375 ml - Formulary's Spotting Reducer II For Paper is the classic Farmer's Reducer. The solution acts by conversion of the silver metal in the print to silver bromide. The reducer can be used to…
www.freestylephoto.com

My understanding is that the Potassium Bromide in a bleach like the one from Moersch allows the print to be redeveloped, while the hypo in Farmer's reducer would obviously prohibit re-development. Having the option to re-develop sounds appealing. The Moesrch bleach also comes as a liquid concentrate which I prefer to mixing powdered chemicals, which is necessary with Farmer's Reducer. I do understand that I will need to re-fix a print if bleached using the Moersch product.

Are there any downsides to the Moersch Bleach? I don't hear much about it. Does it possibly have a shortened shelf life due to it being in liquid form? Any health/safety concerns with using a product containing ferricyanide? I understand that it needs to be kept away from strong acids and heat, but are there any other precautions required when using it (other than not eating it )?
 
logan2z said:
Does it possibly have a shortened shelf life due to it being in liquid form?
Click to expand...

I'm pretty sure the shelf life of the potassium ferricyanide/potassium bromide mix is longer than my own shelf life .

logan2z said:
My understanding is that the Potassium Bromide in a bleach like the one from Moersch allows the print to be redeveloped, while the hypo in Farmer's reducer would obviously prohibit re-development.
Click to expand...

Absolutely right. Adding the sodium thiosulfate prohibits redevelopment. Mixing the sodium thiosulfate with the potassium ferricyanide/potassium bromide mix is also what shortens the longevity of the bleach.

That said, I've never tried the Moersch, so I have nothing to say about that specific product.
 
The PF "Farmer's Reducer" is way stronger than the former Kodak version if you follow their own tip sheet. I dilute considerably more for use than PF recommends. Mixing the powders into separate A&B concentrates is easy enough; and these last a long time in separate glass bottles. The working solution should be mixed in only enough quantity you actually need right before use.
 
I use the bleach from Moersch. Works perfectly well and keeps acting for a long time when diluted.
So no need to worry about the concentrate. Yes if you don't redevelop you need to fix the print.
 
Or, you could just get some potassium ferricyanide and some potassium bromide and use these to mix your own stock solutions. If you are just going to use it for bleaching prints, make up a 10% w/v solution of each. Then it's simple to mix a bleach: take equal parts of both stock solutions and add water to the desired strength. FWIW, for the small amount I use for local bleaching, I start with 50ml water and add two to four eyedroppersful of each stock solution. It's best to start weak. If the bleach isn't strong enough, add small equal amounts of each stock solution. You'll figure out how much works for you quickly.

Prints can be redeveloped to a certain extent, but the bleached areas may tone differently. Still, I've saved many prints by redeveloping a slightly over-bleached area. Prints should be washed for about five minutes in running water before bleaching to get the residual fixer level down to where it won't influence the bleaching if you're bleaching right after the fixing step. Prints need to be refixed and washed after bleaching.

You can work with the bleach solution as long as it stays a nice yellow. When it starts to go green, it's time to toss it.

Best,

Doremus
 
Guillaume Zuili said:
I use the bleach from Moersch. Works perfectly well and keeps acting for a long time when diluted.
So no need to worry about the concentrate. Yes if you don't redevelop you need to fix the print.
Click to expand...


Thanks for the responses, much appreciated.
 
Keep in mind when refixing the print after using bleach without hypo you should use sodium thiosulfate, not ammonium thiosulfate. Some people (barnbaum and on this forum i believe) have experienced yellow staining from refixing with ammonium thiosulfate (rapid fixer).

They will also work in a different way, the bleach without hypo works slower but change is only really visible after fixing, the bleach with hypo is visible during bleaching but works quicker.
logan2z said:
(other than not eating it )?
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fun fact: potassium ferricyanide is found in table salt, so you've eaten it already (still not a good idea to eat it)
 
DutchDarkroom said:
...but works quicker
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As I've discovered last week...

Bleaching is an art that takes quite a while to master. Takes a lot of practice. You have to be ready to waste a lot of prints if you use it mixed with hypo.

Best advice I got from a darkroom colleague after my mishaps: "This is the reason why you should never throw away your test strips."
 

+ 1

Karl-Gustaf
 
I always thought bleaching with Farmer's was easy. Just a few key tricks to it, AND the fact that not every kind of paper bleaches neutral, without a slight warmish color shift in the bleached area. Some papers bleach much easier than others. Nowadays I mostly use Ilford MGWT and MC Cooltone, which do bleach easily and consistently. Last year I tried bleaching a few Foma Neutral tone prints - now that was a pain in the butt!
 
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DutchDarkroom said:
Keep in mind when refixing the print after using bleach without hypo you should use sodium thiosulfate, not ammonium thiosulfate.
Click to expand...
Amm. thiosulfate works fine really.

DutchDarkroom said:
the bleach without hypo works slower but change is only really visible after fixing,
Click to expand...
Ferricyanide/bromide bleach really is visible as you work.
 
Just one thing to add: Wolfgang warns that hardening the emulsion before bleaching may be good idea if you want to preserve the gloss of the surface. That is the exact problem I ran into when bleaching and subsequently thiocarbamide toning MULTIGRADE FB CLASSIC Glossy which developed a rather uneven rough surface in the process. Easy to detect, easy to fix, Wolfgang offers the needed hardener too. I also recommend to start with higher dilutions of the bleach for better control of the process.
 
I've had the experience that prior selenium treatment alters the bleaching process in a way that made it easier to be more subtill with the outcome.
 
koraks said:
Amm. thiosulfate works fine really.


Ferricyanide/bromide bleach really is visible as you work.
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My experience as well.

Over-bleaching will cause discoloration on many papers. Often, a partial redevelopment will bring the color back to match the rest of the print. As I mentioned earlier, be careful toning bleached prints as the bleached areas can tone differently.

Doremus
 
Saganich said:
I've had the experience that prior selenium treatment alters the bleaching process in a way that made it easier to be more subtill with the outcome.
Click to expand...
A partial toning with selenium will make some of the silver in the print unbleachable, thus slowing down the bleaching process by limiting to the untoned silver grains in the print. Diluting you bleach will slow things down as well.

Doremus
 
Doremus Scudder said:
Over-bleaching will cause discoloration on many papers.
Click to expand...
Yes; not sure if we're talking about the same thing, but note that as density is reduced with a bleach, the silver grain size and geometry changes, and this tends to produce warmer hues. I.e. the image tone will actually change in the bleached areas. This will be dependent on the paper, how it was developed and the extent to which it's being bleached.
 

I've got a bottle of Moersch bleach on the way. I'm interested to see how many of the potential issues cited in this thread I actually run into
 
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