Lighten Dark Print?

analog65 · May 20, 2016

I am looking for ideas on how to possibly lighten up a dark print. I made a couple Harman direct positive b/w prints that are very nice, but I was off a little bit on the exposure and they are too dark. Any suggestions on how to lighten the print a little bit?

Doremus Scudder · May 21, 2016

Bleach them in a dilute ferricyanide bleach. I prefer a rehalogenating bleach of ferri and potassium bromide, but Farmer's reducer will work too. Use a weak dilution and a test print to help you determine time. Bleach under display lighting and pull the print before the desired degree of bleaching is reached as it will continue bleaching a bit in the rinse. You can always return the print to the bleach if you need.

Bleaching-back is a time-honored practice that was used a lot by newspaper darkrooms. It was faster and easier to print a bit dark and then bleach to the desired tone than to change exposure and make another print.

Best,

Doremus

David Allen · May 21, 2016

In my notebook, I have the following formula that I used when working in a commercial darkroom.

Stock Solution A:
Water 250ml
Potassium Ferricyanide 64g
Potassium Bromide 30g

Stock Solution B:
Water 500ml
Sodium Thiosulfate 120g

For use normal use, mix 7.5ml of solution A with 180ml of solution B and then add water to make 500ml.

Next to the formula, I wrote in large type "works too fast, now using 7.5ml of solution A with 180ml of solution B and then add water to make 1,000ml"

From memory this more dilute version was much more controllable which I presume is important as you wrote "Any suggestions on how to lighten the print a little bit?"

As with all reducers, it is best if you pull the print before the desired degree of lightening is achieved. Wash it, assess it and then, if required, bleach a little more. When you want to slightly lighten a print taking it slow and careful is the way to go every time.

Bests,

David.
www.dsallen.de

ColColt · May 21, 2016

As with all reducers, it is best if you pull the print before the desired degree of lightening is achieved. Wash it, assess it and then, if required, bleach a little more. When you want to slightly lighten a print taking it slow and careful is the way to go every time.

There you go. Check it out often to see where you are. Once I had the proper lightening I'd dunk it in fixer then wash.

Doremus Scudder · May 21, 2016

ColColt said:
There you go. Check it out often to see where you are. Once I had the proper lightening I'd dunk it in fixer then wash.

Rinse well before "dunking it in the fixer," especially if you are using a ferri/bromide bleach. The fixer will activate the ferricyanide and bleach more. You want to rinse the ferricyanide out of the print before re-fixing. If you need more bleaching, rinse well first to eliminate carry-over of fixer, which can result in speeding up the bleaching reaction and possibly be uncontrollable.

Best,

Doremus

ColColt · May 21, 2016

The bleaching does not stop immediately upon contact with the fixer but takes a few seconds. I would think it would stop it better/quicker than just a dip in water first. Worked for me. Either way, I'd pull the print prior to achieving the desired effect.

gone · May 21, 2016

This might save my butt. Glad I saw this. My very first darkroom print is surprisingly nice, but it's too dark due to my inexperience w/ test strips. If I could get it lightened and put on the wall that would be a happy occasion, just for a keepsake.

Doremus Scudder · May 22, 2016

ColColt said:
The bleaching does not stop immediately upon contact with the fixer but takes a few seconds. I would think it would stop it better/quicker than just a dip in water first. Worked for me. Either way, I'd pull the print prior to achieving the desired effect.

The way fixer affects the bleaching depends on the type of bleach used. If you are using a Farmer's reducer type bleach, i.e., one that consists of ferricyanide and thiosulfate, then there is "fixer" in the bleach already, which is speeding up the bleaching reaction. Transferring a print directly to the fixer from this type of bleach will not do too much in the way of increased bleaching, however, the print will still keep bleaching till the ferri is exhausted. A water bath will stop it more quickly.

If you are using plain ferricyanide or a ferri/bromide rehalogenating bleach (i.e., one without thiosulfate) then you are using a bit stronger dilution to begin with. Dunking this print directly into the fixer will result in the bleaching action suddenly being accelerated by the addition of thiosulfate. Similarly, if you pull a print from the fixer and return it to such a bleach without intermediate rinse, the carried-over thiosulfate will speed up the action of the bleach quite a bit compared to its activity without any carry-over.

Best,

Doremus

analog65 · May 26, 2016

I wanted to say thank you for the suggestions. I ordered some ferricyanide and it should be here in a few days.

RalphLambrecht · May 27, 2016

Doremus Scudder said:
Bleach them in a dilute ferricyanide bleach. I prefer a rehalogenating bleach of ferri and potassium bromide, but Farmer's reducer will work too. Use a weak dilution and a test print to help you determine time. Bleach under display lighting and pull the print before the desired degree of bleaching is reached as it will continue bleaching a bit in the rinse. You can always return the print to the bleach if you need.

Bleaching-back is a time-honored practice that was used a lot by newspaper darkrooms. It was faster and easier to print a bit dark and then bleach to the desired tone than to change exposure and make another print.

Best,

Doremus

+! A !% solution for 1 min is a good start. You need to fix afterwards and give it a complete wash again.You can repeat the process until the print is to your liking but it's better to use a weaker solution several times than a strong solution once. I've done it with solution as weak as0.5% with success. beware, the highlights will bleach first and most.You are best of bleaching dark midtowns locally with a cotton swab;also followed up with a cotton swab fix; or mix bleach and fix 1:1 as in Farmers reducer. experiment with a test print first.good luck

analog65 · Jun 7, 2016

Thank you!!

RalphLambrecht said:
+! A !% solution for 1 min is a good start. You need to fix afterwards and give it a complete wash again.You can repeat the process until the print is to your liking but it's better to use a weaker solution several times than a strong solution once. I've done it with solution as weak as0.5% with success. beware, the highlights will bleach first and most.You are best of bleaching dark midtowns locally with a cotton swab;also followed up with a cotton swab fix; or mix bleach and fix 1:1 as in Farmers reducer. experiment with a test print first.good luck

jeztastic · Jul 17, 2016

I am about to attempt exactly the same thing. I have ordered some Potassium Ferricyanide as part of a cyanotype kit, but I will be using some of it to bleach a print. How many grams of Potassium Ferricyanide will I need to mix to get a stock solution?

paul_c5x4 · Jul 18, 2016

jeztastic said:
How many grams of Potassium Ferricyanide will I need to mix to get a stock solution?

When I use Pot.Ferri. I usually mix it to around working strength rather than keeping a stock solution on the shelf. For me, this is between five to ten grammes per litre of water and then diluted further if it is working too fast. If it isn't strong enough, it is easy to add a pinch more Pot.Ferri - The exact quantity of powder is not critical so you could even use teaspoon measures.

Ian Grant · Jul 18, 2016

I'd use a slightly different approach, fully bleach in a re-halogenationg bleach, wash under tungsten/artificial lighting and then re-develop in weaker tha normal developer. The choce of developer would depend on how over exposed the image was, I used to keep a Soft (ID-3) and Hard (ID-14 contrast) developers on my shelf.

Ian

Gerald C Koch · Jul 18, 2016

I have never been very satisfied with a bleached print unless the amount of correction needed was very small. The first thing to do it to evaluate the print under the lighting conditions where it will be viewed. Then work from there.

Rich Ullsmith · Jul 19, 2016

I don't know if the paper OP is using is FB or rc, but if I am to do a general light bleaching with FB paper, I use a strong bleach. Dunk it in the bleach then immediately into water to stop and evaluate. With weak bleach and fiber paper, yes you better pull well before desired results are achieved because the bleach will now be soaked into the base and will continue bleaching in the water stop. Sounds counterintuitive, but with strong bleach and shortest possible exposure to the bleach, the bleach does not have time to soak into the paper base, and bleaching stops very quickly in the water.

M Carter · Jul 19, 2016

Note that you can also spot-bleach - if not overdone it can help pop highlights, brighten teeth and eyes, and so on. Takes a weak ferri-fix mixture, a flat surface, a paintbrush and a running water hose - and a light touch. Several videos and articles out there.

(this isn't that great with lith prints that have color though - often color in lith is really delicate and you'll have colorless spots where you bleach. And I've found with ektalure, the paper finish dulls where bleached and makes it very visible).

Lighten Dark Print?

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