RE: more dag questions and some answers

From: Robert W. Schramm ^lt;[email protected]>
Date: 01/11/04-04:41:59 PM Z
Message-id: <>

The Becequerrel process uses only iodine fuming. (I don't know why) It is
less sensitive than the mercury process. Exposure time may run up to 20
minutes. The plate is developed in red light and development may take
several hours. The iodine fuming is more complex than with mercury. Still,
the finished plates look just as good as the mercury plates (in my opinion)

The mercury processes requires iodine fuming followed by bromine fuming
followed by iodine again. It is much more sensitive. At f 5.6 and bright
sunlight, exposure can be 15 to 30 seconds. The plates are developed in
mercury vapor which is obtained by heating liquid mercury. Dipping thge
plate in mercury metal won't do anything . Maybe if you left the plate
suspended over a dish of mercury for a couple of weeks you might get some
development, I don't know. Forget the regular developer, this is a different
process than silver/gel. Mercury process pates are fixed in hypo and washed.
I don't know about Becquerrel process plates.

A few years back I found a 150 mm f 2.8 Schneider lens. There must be more
out there somewhere. It cut my exposure times way down.

Bob Schramm

Check out my web page at:

>From: Stuart Plotkin <>
>Subject: more dag questions
>Date: Fri, 09 Jan 2004 22:53:06 -0500
>Do most of you making Daguerreotypes use the Becquerel method or do any use
>the mercury process. Is it true that the mercury process gives a better
>result, or does it depend on who you ask? Has anyone tried just dipping the
>exposed plate in mercury, that would be safer- I assume this has been tried
>and didn't work. What would happen if you use a conventional developer?
>Would you end up with a negative instead of a positive? Does anyone know
>why with the mercury process do you coat the plate with iodine, bromine and
>iodine but in the Becquerel process you use only iodine? Doesn't the
>bromine make the plate more sensitive? i was talking to my old chemistry
>professor at college about mercury fumes and perhaps constructing a closed
>system that does not allow any mercury vapor to be released, or perhaps a
>distilling apparatus that cools and condenses the vapors to be easily
>collected. He also said that sulphur acts like a sponge and will soak up
>any mercury vapor and turn it into!
> a harmle
>o you think?- Stu

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Received on Sun Jan 11 16:42:09 2004

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