[Alt-photo] Cerium Ozotype

jimbobnola at cox.net jimbobnola at cox.net
Fri Mar 11 19:09:44 UTC 2016


Hi Kees,
Yes, exactly.  I find that the Ceriuim Ozotype has a longer scale than the Ferricyanide Carbon, which is rather short.  Exposure is much shorter with Cerium than the Ferricyanide. 
Jim
---- Kees Brandenburg via Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org> wrote: 
> Hi Jim,

I must have misread your original recipe…

So, if I understand correctly now, the final transfer substrate, gelatin coated, is sensitized and exposed under a positive. Then the, in 1 % oxalic acid soaked, pigment paper is mated quickly in the acid bath with the dry exposed final paper. During the mating time the reaction between the acid and the ‘exposed’ cerium takes place, thus hardening the pigment.

Nice…

I’l try to find some Cerium IV Ammonium Nitrate.

Kees



> On 11 mrt. 2016, at 16:31, Jim Patterson via Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org> wrote:
> 
> Hi Kees,
> The final support paper is what is coated with cerium IV and is the final print.  If soaked too long in the oxalic acid the cerium IV starts leaching out and can cause a blurry image.  You can experiment with soaking times, but I just worry and do it fast.  You cannot coat the C tissue with the cerium IV, it permanently hardens the gelatin.  Cerium III oxalate is white and fairly stable.  It can be removed with ammonium oxalate solution or potassium oxalate solution, perhaps after fixing the image with glutaraldehyde, or perhaps that is not necessay.  I haven't done it.  By the way, cerium III oxalate was the invisible ink used by East Germany KGB spies in the cold war.  
> Jim

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