Liz, I think that would be really wrong. From a purely aesthetic
POV, the solder would discolour differently to the silver, over time
- I’ve encountered lots of jewellery done with soft solder, and it’s
invariably visible from a foot away, or more.
Secondly, check that the solder is rated for skin contact - just
because it is lead-free and suitable for slight contact with water
doesn’t mean that it is good for the skin. It might contain a wide
range of different metals and chemicals, any of which could cause
allergic reactions for different customers.
From a more technical perspective, soft solder is usually intended
for connecting large surfaces together -when I’ve encountered
soft-soldered items, the joins were very weak, and you can sometimes
almost “tear” the solder by bending the join - the result is
granular, and clearly not very strong.
Someone else might be able to correct me here, but I think that
there may also be some fusing of silver solder and the silver itself,
which gives the join a great deal of strength. Soft solder is
unlikely to have that property, except by luck or coincidence.
(Note: When I say “soft”, I mean low melting temp. solder, not