Thanks Steve, I would like to try some of it out. I have an inexpensive geiger counter here.
I haven't heard of a German paper, so it would be interesting. Not sure if they used Thorium, as there are non-radioactive mordants which work almost as well.
BTW, maybe this topic is better on the dyetransfer forum - I know you posted there, I should have replied there.
To try to bring this on-topic: I made a trough coater (
www.dyetransfer.org ) which I used to coat Baryta and hot-press fiber papers to try different dye transfer paper looks. I tried Thorium Nitrate as the mordant, and both pre-hardening and post hardening. It was difficult with the pre-hardener (Formalin, with Resorcinol added) as you had to work fast before you ended up with an insoluble radioactive blob - uggh! By leaving out the hardener, I could just add the thorium nitrate as a mordant, and coat onto baryta base, and save any left over gelatin for later. Later, I would use a strong solution of formalin in a tray to harden the gelatin later. Worked very well.
One interesting thing that I tried was to make a dye transfer paper with a very light gelatin sizing. The resulting paper had a very low gloss look which was nice. I thoriated some gelatin and coated it onto Arches Hot Press paper - only a sizing really. Normally if you tried to transfer a dye image to this treatment, it would bleed into the paper fibers quite quickly making a mess. I decided to pre-treat the paper with a mixture of silicone microscope oil and mineral spirits. The silicone dissolved readily in the mineral spirits, soaked into the paper fibers, and dried well. I then coated the paper with the gelatin / thorium and let it dry. This worked very well, even though there was no baryta layer to seal the dyes out of the fibers, they didn't bleed at all because they were repelled by the silicone.
Regards - Jim Browning
Digital Mask
187 Stevens Rd.
Lebanon, NH 03766
603-448-6241