Since I have some history on using copper in alternative printing ( see my little article in Post  Factory # 9 as well as  here ), I was very interested in a variant designed by Jim Patterson ( kindly shared through Christina Anderson on the list).

Jim coined his variant "Cuprotype"

I gave his method a try, and I am realy pleased with the result (although I only did one short printing session). I think it's realy an improvement compaired to my method (whch was actually designed by Chris Patton). The advantages beeing realy clean highlights and contrast control through AmmoniumDichromate (did not try that with my method, I assume that it will work). There is also no need to coat the paper first with agar. A slight disadvantage is that the process "consumes" quite some chemistry (although not very expensive), and takes some time in post processing (especially the last step washing out the potassiumferricyanide takes time and attention)


Click on the images to obtain a larger one

Film: 4*5 MACO IR film (prototype), 89b red filter, at 6 ASA,
PyrocatHD developer.

Paper: Simili Japon
Coating: 2 * 200 ul sensitiser
+ 1,5 ul AmmoniumDichromate
+ 1 ul PhotoFlow
 (dried after first coating),
coating rod.

Exposure : 14 minutes under home made UV bank.
Processed according Jim Patterson
Same coating as above.
Half a stop less exposure (10 min)
1 minute Amidol toner
Heat dried.

The Amidol toner intesifies about half a stop


Nice colour shift from red/brown to purple/redd/egg-plant colour
8*10 HP5+ negative
Exposed at 250 asa,
PyrocatHD developer

Coating:
2* 1ml +10 ul Tween20
+ 10 ul Ammonium Dichromate (20%)
Exposure: 30 minutes.
(this negative has a to high Dmax, increasing exposure more lowers contrast, but the shadows do not get stronger, perhaps because the printing out effect. The shadows already form during exposure and prevent further deepening).
Amidol toning nicely balance this effect


Enjoy!

Best,

Cor Breukel, 29/10/2007