Quote Originally Posted by JG Motamedi
Donald,

Great comments. Actually in current usage, Becquerel development can be done in about 2 hours using amberlith or rubylith with either a 500watt light or direct sunlight. Since Becquerel plates don't benefit from bromine fuming it is a simpler process, but about 2.5 stops slower. Also, Iodine doesn't have to be heated. The fumes created at room temperature are enough.
Interesting thread as a friend and I are about to try making a Becquerel daguerreotype this summer - we are in the very early phase of trying to figure this out.

You say that the speed is about 2.5 stops slower than a mercury fumed daguerreotype. What ISO would be a good place to start our exposure calculations?

Thanks.

Ehud

PS: If anyone knows a place in Vancouver BC where I can buy some rubylith, please let me know.