A couple of cupric / copper based bleaches I have "harvested" off the internet follow.
I have not used them so proceed with appropriate caution.
------------------
Cupric Sulfate Bleach from Ann Clancy A bleach for redevelopment.
Cupric sulfate (Copper Sulfate) 50g
Sulfuric Acid concentrated* 6.5 mL
Sodium Chloride 100g
Cold water to 1000 mL
always add acid to water
-------------------------------
PE offers a information on copper based bleaches:
my same caution applies (though in this case, PE is a sterling source).
Bleach Baths from Cupric Sulfate
Variation A
490mL Distilled Water
5g Cupric Sulphate
10mL Sulphuric Acid (98%)
Variation B
490mL Distilled Water
10g Cupric Sulphate
25g Potassium Hydrogen Sulfate
Variation C
490mL Distilled Water
5g Potassium Dichromate
10mL Sulphuric Acid (98%)
Cupric Sulfate is a well known bleach for films. There are many patents on it in the literature. I have worked with it myself. The problems are threefold; the first is that the bleach will not work if there is not enough acid, and the second is that the copper salts can stain the film or paper and cannot be removed and the third is that these bleaches are very slow in most cases. There are also blix formulas.
Concentrated sulfuric acid (Oleum) is pretty much unobtainable. You can get dilute sulfuric acid at auto stores (about 37%) and from the Formulary (about 48%). The 48% is the highest that can be shipped now in the US without a special license.
A drop of oleum on the skin does not cause immediate burns due to lack of water. It needs water to react. So, immediately start a huge flow of cold water in the nearest tap and wash it off as quickly as possible with as much water as possible. Do not leave it on the skin for over 30". When you wash it off, you will feel an instant burning sensation and a lot of heat, as the reaction starts. If you wash with enough water, fast enough, no harm will be done in most cases. Once rinsed well, put some sodium bicarbonate on the affected area for about 1/2 minute and then re-rinse in cold water. If the skin is broken, call a doctor or go to emergency immediately. Do not get it in the eyes.
PE
-----------------------------
Another bleach of origin I did not record:
Water (40°C) 750 ml
Copper sulfate 50 g
Sulphric acid (10%) 65 ml
Sodium chloride 50 g
Water to make 1000 ml
Hi Thomas, the cupric sulphate bleach I am using is like the first variant given by CBG, but instead of sulphuric acid I am using sodium hydrogen sulphate (sodium metabisulphate, sold as "Dry Acid" for adjusting the pH of swimming pools); this is safer to use than concentrated acid (also easier for me to get hold of), and I use it at an equivalence of around 5.5g == 1ml of concentrated acid. I.E. in the Ann Clancy variant above, I would use about 35g of sodium metabisulphate in place of the 6.5ml of conc sulphuric acid.
For the ferri bleaches I have a 10% stock solution of potassium ferricyanide, which I dilute and add halide as required. For my standard bleaches I dilute the stock ferri 1+3 with water, then add around 10g per litre of the required halide, either sodium chloride (I use salt for the regeneration of ion exchange resins in water softeners, rather than table salt), potassium bromide, or potassium iodide. At this concentration, a print will be fully bleached in about 1.5 - 2 minutes, but provides reasonable control for split toning.
If you need the bleach to work faster, mix it 1+2, or even 1+1; if you want more control for subtle bleaching of the highlights dilute it further, I will occassionaly use it as dilute as 1+39. There is also a series of four photographs in my gallery showing the effect of partial bleaching, and full bleach/redevelopment on subsequent selenium toning.
__________________
Steve
"You don't need eyes to see, you need vision" - Maxi Jazz
Hi Thomas, the cupric sulphate bleach I am using
is like the first variant given by CBG, but instead of
sulphuric acid I am using sodium hydrogen sulphate
(sodium metabisulphate, sold as "Dry Acid" ...
My bottle of the granulated is marked sodium bisulfate.
A pyro may be made of it by heating; the meta? The
bisulfate is often a substitute for the acid.
It is safe to handle.
As I've mentioned there is the bleach then what follows.
All of the bleaches are oxidizers. FerrrIcyanide converts
the silver image to silver ferrOcyanide. Although no one
has taken credit for testing, I believe that the silver
ferrOcyanide image can be toned. No halide or ???
needed.
With the cooler weather I can make it back to the
darkroom. I'll take the credit myself.
Sponsored Ad. (Subscribers to APUG
have the option to remove this ad.)
My bottle of the granulated is marked sodium bisulfate.
A pyro may be made of it by heating; the meta?
You are correct Dan, serves me right for battering away on the keyboard before fully engaging my brain!
Quote:
Originally Posted by dancqu
As I've mentioned there is the bleach then what follows.
All of the bleaches are oxidizers. FerrrIcyanide converts
the silver image to silver ferrOcyanide. Although no one
has taken credit for testing, I believe that the silver
ferrOcyanide image can be toned. No halide or ???
needed.
I also believe that is correct. Instead of using Farmer's reducer, it is possible to bleach with ferri, then fix, with the option to redevelop the image if you bleach too far, that redevelopment can be performed with a suitable toner to give a permanent toned image.
The addition of the halides just provides a varying electronic environment for toning/redevelopment of the silver ferrocyanide, therefore affecting the final form of the toned/redeveloped silver.
__________________
Steve
"You don't need eyes to see, you need vision" - Maxi Jazz
I've used the bleach separately. I mix up the stock solution the way it's described on the package and then I dilute anywhere from 1:5 to 1:20 depending on how much of the sepia tone I want the paper to develop, and it also varies a lot from paper to paper how much it tones.
Ilford MGWT - crazy stuff. Tones very heavily and is beautiful. 1:15 bleach.
Fotokemika Varycon - subtle. Needs a kick in the ass to react, but once there - oh my! 1:5 bleach.
Fotokemika Emaks - honey golden sepia tone. Extremely beautiful. 1:10 bleach.
Forte Polygrade - almost unpleasing sepia tone, very dull looking. But if you get the contrast really stark in your printing, you can get the highlights to glow very nicely. 1:10 bleach.
Those are dilutions for about 2 minutes bleach, after which I soak the print in a water bath to rinse, then hypo clear, then water again with a couple of water exchanges. Then I tone in the sepia for about one minute, but the effect is rather immediate. The re-development is very rapid.
If you add selenium afterwards at about 1:10 or so, the golden highlights, especially on the Ilford, really start to kick in with a wonderful split red/golden tone that is kick butt in a cloudy sky.
My practical observations include that this is a lot easier than it seems, but that hygiene is important. Wear nitrile gloves, work with caution, and preferably in a VERY well ventilated darkroom or outdoors if possible. But oh boy is it fun. I recommend trying one single paper to begin with and learn it, much like when you start printing or start using/developing film. It takes a while to learn the inns and outs.
- Thomas
Quote:
Originally Posted by CBG
Thomas,
Were you mixing the Kodak Sepia II and Selenium together to use them as a single solution or using them separate sequentially?
And in what strength were you using them? Any detail you can add would help people make use of your interesting combination.
Thanks!
C
__________________
------------------------------------------------------ Photographing my soul! = = = = Please visit my APUG Portfolio
A couple of cupric / copper based bleaches I have "harvested" off the internet follow.
I have not used them so proceed with appropriate caution.
------------------
Cupric Sulfate Bleach from Ann Clancy A bleach for redevelopment.
Cupric sulfate (Copper Sulfate) 50g
Sulfuric Acid concentrated* 6.5 mL
Sodium Chloride 100g
Cold water to 1000 mL
always add acid to water
-------------------------------
PE offers a information on copper based bleaches:
my same caution applies (though in this case, PE is a sterling source).
Bleach Baths from Cupric Sulfate
Variation A
490mL Distilled Water
5g Cupric Sulphate
10mL Sulphuric Acid (98%)
Variation B
490mL Distilled Water
10g Cupric Sulphate
25g Potassium Hydrogen Sulfate
Variation C
490mL Distilled Water
5g Potassium Dichromate
10mL Sulphuric Acid (98%)
Cupric Sulfate is a well known bleach for films. There are many patents on it in the literature. I have worked with it myself. The problems are threefold; the first is that the bleach will not work if there is not enough acid, and the second is that the copper salts can stain the film or paper and cannot be removed and the third is that these bleaches are very slow in most cases. There are also blix formulas.
Concentrated sulfuric acid (Oleum) is pretty much unobtainable. You can get dilute sulfuric acid at auto stores (about 37%) and from the Formulary (about 48%). The 48% is the highest that can be shipped now in the US without a special license.
A drop of oleum on the skin does not cause immediate burns due to lack of water. It needs water to react. So, immediately start a huge flow of cold water in the nearest tap and wash it off as quickly as possible with as much water as possible. Do not leave it on the skin for over 30". When you wash it off, you will feel an instant burning sensation and a lot of heat, as the reaction starts. If you wash with enough water, fast enough, no harm will be done in most cases. Once rinsed well, put some sodium bicarbonate on the affected area for about 1/2 minute and then re-rinse in cold water. If the skin is broken, call a doctor or go to emergency immediately. Do not get it in the eyes.
PE
-----------------------------
Another bleach of origin I did not record:
Water (40°C) 750 ml
Copper sulfate 50 g
Sulphric acid (10%) 65 ml
Sodium chloride 50 g
Water to make 1000 ml
---------------------
C
__________________
------------------------------------------------------ Photographing my soul! = = = = Please visit my APUG Portfolio
[QUOTES=snallan;684450]
"I also believe that is correct. Instead of using Farmer's
reducer, it is possible to bleach with ferri, then fix, with
the option to redevelop the image if you bleach too far,
that redevelopment can be performed with a suitable
toner to give a permanent toned image."
Well I wasn't sure but thought it reasonable. I don't
recall any one ever having mentioned the results of
toning after a bleach only. Bleach with a halide or
a halide immediatly following is the norm.
"The addition of the halides just provides a varying
electronic environment for toning/redevelopment of
the silver ferrocyanide, therefore affecting the final
form of the toned/redeveloped silver."
Could be that the toning of the 'ferrO' image does
not give good results. BTW, what other than sulfur
and selenium will give good results toning the 'ferrO'
or rehalogenated image? Dan
Could be that the toning of the 'ferrO' image does
not give good results. BTW, what other than sulfur
and selenium will give good results toning the 'ferrO'
or rehalogenated image? Dan
I only ever experimented with non-halogenated bleach baths when toning, and don't use them for regular toning. Thiocarbamide sepia, and selenium definitely tone the silver in the ferrocyanide form, I didn't try other toners.
The thiocarbamide sepia toner acts incredibly quickly, toning a print in 15 - 20 seconds (due to the presence of the hydroxide ion? Possibly).
The selenium was a bit problematic, it does tone the the silver, but I remember getting a lot of leaching of the toned silver from the image, leaving a weak image, and murky toner. Possibly due to a similar process that forms the "soluble" prussian blue in some of the cyanotype processes. Varying the concentration of the selenium toner might give different effects, but this was really just a bit of experimenting for fun.
__________________
Steve
"You don't need eyes to see, you need vision" - Maxi Jazz
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