Máx Arnold
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Hello all, hope you're doing great!
I have become quite dormant on the forum, but I have slowly kept working. I recently rediscovered a Copper based process while I was working with Cuprous Chloride emulsions, I am going to share my lab notes and some examples in hopes you want to try it too.
This process is not formal (there's no standard procedure) yet. I do not fully understand it yet, but it's very promising. I will be attaching a formal procedure when I have investigated it more.
This is a Printing Out Process which makes use of a mixture of chelated Cu(I) and Liver of Sulphur (Potassium Sulphide and a mixture of polysulphides). The liquid sensitiser is not air sensitive, and under strong sunlight the image develops in sepia tones. It does not seem to benefit from fixing, apart from just needing a distilled water wash.
These are my lab notes from when I made the print I'll show you:
– to aqueous Copper Sulphate add Oxalic Acid until a light blue precipitate stops forming. Mix thoroughly and let set a little.
– create a buffer solution around pH 4.5 by mixing ascorbic acid and sodium bicarbonate.
–take the supernatant with the tiniest particles of precipitate from the first procedure, and mix with the Ascorbic acid buffer. The solution should clear into a lime green colour.
– add Liver of Sulphur with a couple drops of surfactant drop wise until the foam stops being blue and turns white.
This is the sensitiser and is instantly ready to use. Keep away from light.
Use a nice, absorbent and unbuffered watercolour paper. So called Cotton Sketch paper is good. Fabiano, Canson, all that should be good.
– Coat with a brush, and dry fully to prevent uneven exposure.
– Expose under a negative and glass plate for about 10 minutes in full sun. YMMV
Once it's exposed, the image should have appeared in a sepia tone.
– Wash with distilled water to remove any unreached salt.
– Dry.
This process seems to make use of the strong chelating effect AND photosensitivity of Oxalic Acid. The Copper (I) ion is fully sequestered in the complex, away from oxygen. When the acyl groups in the oxalate receive photons, they transfer their delocalised electron to the Copper, which instantly reduces and falls out of solution, then easily attacked by the sulphide to become fully stable and insoluble Copper (I) Sulphide.
Any comments are greatly appreciated
I have become quite dormant on the forum, but I have slowly kept working. I recently rediscovered a Copper based process while I was working with Cuprous Chloride emulsions, I am going to share my lab notes and some examples in hopes you want to try it too.
This process is not formal (there's no standard procedure) yet. I do not fully understand it yet, but it's very promising. I will be attaching a formal procedure when I have investigated it more.
This is a Printing Out Process which makes use of a mixture of chelated Cu(I) and Liver of Sulphur (Potassium Sulphide and a mixture of polysulphides). The liquid sensitiser is not air sensitive, and under strong sunlight the image develops in sepia tones. It does not seem to benefit from fixing, apart from just needing a distilled water wash.
These are my lab notes from when I made the print I'll show you:
– to aqueous Copper Sulphate add Oxalic Acid until a light blue precipitate stops forming. Mix thoroughly and let set a little.
– create a buffer solution around pH 4.5 by mixing ascorbic acid and sodium bicarbonate.
–take the supernatant with the tiniest particles of precipitate from the first procedure, and mix with the Ascorbic acid buffer. The solution should clear into a lime green colour.
– add Liver of Sulphur with a couple drops of surfactant drop wise until the foam stops being blue and turns white.
This is the sensitiser and is instantly ready to use. Keep away from light.
Use a nice, absorbent and unbuffered watercolour paper. So called Cotton Sketch paper is good. Fabiano, Canson, all that should be good.
– Coat with a brush, and dry fully to prevent uneven exposure.
– Expose under a negative and glass plate for about 10 minutes in full sun. YMMV
Once it's exposed, the image should have appeared in a sepia tone.
– Wash with distilled water to remove any unreached salt.
– Dry.
This process seems to make use of the strong chelating effect AND photosensitivity of Oxalic Acid. The Copper (I) ion is fully sequestered in the complex, away from oxygen. When the acyl groups in the oxalate receive photons, they transfer their delocalised electron to the Copper, which instantly reduces and falls out of solution, then easily attacked by the sulphide to become fully stable and insoluble Copper (I) Sulphide.
Any comments are greatly appreciated