I used to do a lot of this (20+ years ago), in fact did a master's thesis
in it. I am dredging my memory.
You can minimize the danger rather easily. You do need very good
ventilation, and Dick Sullivan's comment is very much to the point.
You can use very dilute Nitric acid. Silver solder a wire to your work
piece. Glob asphaltum on the wire. Then you can use it as an anode at a
low voltage, say around 1-3 volts. For a cathode, use just a piece of
copper. You will be plating the copper with a low-grade silver deposit.
The workpiece will be etched.
You can use a circuit resist for the image. This will limit you to
halftones, or some other screening method, which will have to be achieved
using a lith film intermediate. I have not followed what is available,
but there are surely products out there. Try this url:
"http://www.10mb.com/zacryl/page4.html". It looked to me, last I saw it,
like it would work.
You need a good pickle, for cleaning the silver. Consult a good jewelry
book. I have a very good one called _Metalwork and Enameling_,
unfortunately I can't lay my hands on it just now so can't give
author/publisher info, but it's a classic. Also, for degreasing,
consider plain old Red Devil Lye. The surface will have to be acidified
after degreasing. This is to get the resist to stick. A dip in the
pickle, and a rinse and dry prior to applying the resist, will probably
do it.
While yes, Luis' suggestion of Daguerreotype is worth considering, most
uses in jewelry require a certain toughness, to say nothing of
solderability. Halftone etched images can be silver soldered, no
problem. They also have a certain boldness and visibility, which a
Daguerreotype definitely would not.
>Maybe someone knows a way to blacken silver by converting it to silver
>sulfide. (sulphide to you Brits!)
Yes, it's called sepia toner (just the toner part; bleach is
unnecessary). Jewelers use a solution of polysulfides. Consider also my
favorite: Selenium toner. Great! Haven't you ever worn silver jewelry
while toning? Try it. This of course, now that we are aware, will have
to be done with the jewelry worn on the outside of rubber gloves. But we
are fashion conscious, so this should be no problem, huh?
What works best is usually to etch, then blacken the etched areas. This
keeps the blackening, which is more fragile, beneath the surface of the
plate. Now, the original black may tend to disappear, but silver
tarnishes and the high surfaces can be touched up occasionally with a
polishing cloth and the inside will remain dark.
Silver is silver and everything we do with it in photography can have
some counterpart in jewelry. The two media are terrific together.
Please keep me informed. I love this stuff, and really have missed doing
it.
Larry Bullis
Skagit Valley College