"Stopping" farmer's reducer

M Carter

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So I'm working with prints in a DIY 30x40" tray and need to do some light reducing. Normally I'd pull the print from the farmer's and go to a water bath, but this tray has drains (one to the sink and one can go to jugs) with rubber stoppers. The prints are emulsion on canvas, very big and heavy, and are pretty delicate. The tray takes a couple minutes to drain. Moving the print to another tray ain't an option since (a) I don't have another tray (not even a bathtub is big enough) and (B) it's like handling a wet quilt.

I doubt I'm in luck here, but will any chemical shut down the ferri action? Well, I guess water will. I assume my best bet is to use a weak and slow solution, and dump a lot of cold water in the tray to dilute it way down when I feel it's close. It would be cool if there was something to chuck in that would more completely "stop" it than just dilution though.

(I suppose I could use the big tray in the bathroom and get the print into a tub full of water, though it would have to curl a bit and has a good chance of wrapping around on itself. Or maybe rig something up outdoors).
 

Bill Burk

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Hose some fresh water on the spot. I saw a great video showing that.
 

Lachlan Young

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The simple answer is to dump fixer on it. That'll stop it all right.

I do however think that you might have an easier time if you use rehalogenation bleach rather than Farmers' reducer - if you go a little too far, you can wash & redevelop etc & then re-bleach till right & then fix - and that you might want to look into the sort of setups that screen printers use for washing out screens. If I'm doing any bleaching (local or overall) I work with a running hose immediately to hand to dilute down the reducer fast & then dunk it into the fix to stop the process.
 

Bill Burk

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The printer is Nathalie Lopparelli and I can’t find the video. Here is a frame shot...
 
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M Carter

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Bill Burk said:
The printer is Nathalie Lopparelli and I can’t find the video. Here is a frame shot... View attachment 260850
Click to expand...

Yep, I've done the hose and reducer and have achieved really impressive control with it - this just needs an overall lightening though, and I've found that even a cotton ball can damage the liquid emulsion (even with hardener in it).

And rigging up to spot-bleach a 30x40 print... guess I could do it outside with a sheet of plywood or something!
 
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M Carter

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I've considered the rehal, but man, this emulsion (FOMA) is really sensitive to stuff like that (which is fun for toning) but redeveloping even in paper developer goes much warmer vs. the neutral I need (When the print is done, I stretch the canvas and then hand-tint it with oil glazes, looks about a foot deep after its varnished). I've found there's just tons of silver in the FOMA, even just straight prints rod-coated on Baryta paper is like the most beautiful paper I've ever worked with.
 

Sirius Glass

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That is because the hardener does not harden until fixed and completely dry. Before that the emulsion is still soft.
 

DREW WILEY

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I have a 24X28 inch sheet of plate glass semi-upright at one end of the sink. It's ordinarily used as a squeegee surface after final print washing, but is also useful when using a rinse hose in relation to Farmer's Reducer. I have a larger board suitable for 30X40 prints nearby. For overall reduction rather than selective, I use a big tray of water for a quick overall rinse. But reduced prints need to be re-fixed and then thoroughly washed.
 
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M Carter

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Yep, I know all of that, I'm thinking you didn't read my post? Large print on canvas; I have one 30x40 tray, the canvas edges don't even rest fully in it (but they're to wrap around the stretcher later, no emulsion on them). Don't have another huge tray, and moving the wet print is difficult and the surface is fragile.

So looks like my best bet is use very dilute reducer, watch carefully with a wet comparison swatch of the tone I want to hit, and then dump in a lot of cold water and start draining the tray when I get close. Maybe even do it outdoors and just dump the whole tray and start rinsing after adding more water.

There was a post that more fix would stop the reaction, but the tray takes 2.5 liters to fill. I have this fear that adding fix would accelerate the bleaching (I guess since fix is part of reducer), but I have no honest knowledge to back that up. I was hoping something like "chemical X will instantly stop the bleaching", which I've never heard of but - one never knows.
 

MattKing

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Reduce the amount of fixer in your farmer's reducer, and use it in a more dilute mix.
It will slow everything down, and and make it possible to do some re-developing if necessary.
Yo will of course have to fully fix at the end.
And don't forget to pack your patience!
Of course, prints too big for a 30x40 tray already encourage patience.
 

drpsilver

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03 Dec 2020

My solution to this is to not use Farmer's Reducer at all. Using just bleach (K3Fe(CN)6 and KBr) allows for almost complete redevelopment. Once one has finished any reductions on the print/negative rince in dilute fix, then wash.

Regards,
Darwin

Edit: Correct spelling error.
 
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M Carter

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I've considered that; but the times I've used it as sort of a "reversible safety reducer", the fixer step usually seems to boost the bleaching. My other issue (mentioned above), is that this emulsion is really sensitive to redeveloping, in that it tends to go very very warm on a second pass, like sepia-toning brown and I need it to remain neutral.
 

MattKing

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M Carter said:
My other issue (mentioned above), is that this emulsion is really sensitive to redeveloping, in that it tends to go very very warm on a second pass, like sepia-toning brown and I need it to remain neutral.
Click to expand...
This is probably related to the re-halogenating bleach you are using - most likely you are switching halogens, and the new halogen is finer grained, and therefore warmer.
The chemists here may have some suggestions about different bleaches.
 

grainyvision

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Have you only tested bleaching using ferricyanide? I've noted that ferricyanide always leaves a particular color about it even when fully bleached and fixed, I assume from the iron in it. Usually not too obvious on traditional materials, but could see it causing less subtle problems on a hand coated emulsion.

One idea might be to use the copper sulfate style bleach, which definitely avoids that problem. It adds the problem of the emulsion becoming much softer though, which may make it impossible in your application. Copper sulfate bleach always uses chloride, which typically gives finer grain and thus warmer results, but I see no reason why you couldn't use something less solvent and bigger like bromide or a bromoiodide mix. Chloride bleach is especially interesting though because it'll "redevelop" simply with sun light, but at a lower density level. Sitting the test print in the sun for about an hour resulted in no change upon fixing. On traditional materials the exposure "redeveloped" image was neutral tone (actually unintended here as I started with a colorful lith print) and a bit lighter, maybe 1/2 stop lighter I assume from chloride having a mild blix affect. Might be something to test if it could be used.

Another idea is to use an extremely powerful fogging redeveloper like sodium dithionite which is sold as iron out cleaning powder. I've only used it a few times for this purpose, but it seemed to reduce anything on the paper into silver and with a ferricyanide bleach gave an image almost identical to what I started with. I used it by simply putting some powder, maybe 1-2 tablespoons into water, then adding 1-2g of carbonate. It only stays good for 1-2 hours at most but is extremely fast acting. Make sure to not mix with acid! (will cause sulfide gas release)
 

drpsilver

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06 Dec 2020

M Carter said:
I've considered that; but the times I've used it as sort of a "reversible safety reducer", the fixer step usually seems to boost the bleaching.
Click to expand...

For this reason I use a 15% to 20% dilute fixer (relative to full strength) to fix the print. With a little practice one can estimate how much to "under bleach" to account for this effect. It is better to bleach -> wash -> fix -> wash -> bleach more if necessary -> repeat wash and fix steps, than to try to bleach in only one step. I cannot remember observing the effect you describe in my workflow.

Regards,
Darwin
 
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