From a paper http://www.znaturforsch.com/ab/v03b/3b0376.pdf (in German) I tried following recipe:
Variant I (Red pictures):
To 25 ml water 0.5 g TTC (Triphenyl tetrazolium chloride CAS: 298-96-4) is added and stirred until a clear yellowish solution is obtained. After that 1 g of sodium hydrogen carbonate is added and stirred again to get a clear solution. This solution is now light sensitive. A paper is now coated and dried about 30 min in the dark. Expose the paper with a digital negative for about 8 min with UV in a vacuum exposure unit. Wash for 5 min in a tray with water and after that a short wash under the faucet and let it dry.
Variant II (Grayish-Violet pictures):
After the first coat with above solution and drying, a second coat with 0.5 g copper(II)sulfate in 50 ml water is applied and dried. Exposure and washing like above.....
Results:
Left Variant I; Right Variant II
Further information with more pictures of this process under https://illumina-chemie.de/viewtopic.php?p=89947#p89947 (in English)
bj68
Variant I (Red pictures):
To 25 ml water 0.5 g TTC (Triphenyl tetrazolium chloride CAS: 298-96-4) is added and stirred until a clear yellowish solution is obtained. After that 1 g of sodium hydrogen carbonate is added and stirred again to get a clear solution. This solution is now light sensitive. A paper is now coated and dried about 30 min in the dark. Expose the paper with a digital negative for about 8 min with UV in a vacuum exposure unit. Wash for 5 min in a tray with water and after that a short wash under the faucet and let it dry.
Variant II (Grayish-Violet pictures):
After the first coat with above solution and drying, a second coat with 0.5 g copper(II)sulfate in 50 ml water is applied and dried. Exposure and washing like above.....
Results:
Left Variant I; Right Variant II
Further information with more pictures of this process under https://illumina-chemie.de/viewtopic.php?p=89947#p89947 (in English)
bj68