Try some experimentation, as different acids will do different
things. I’d suggest making up a simple test plate with a number
of small pieces of your material to try with differing acids.
Nitric acid will definately attack both metals, but may do so at
different rates. Try a fairly dilute solution first, I’d guess.
Etching both metals like this would be to give a slight texture
to the silver parts, and a different texture perhaps, as well as
(hopefully) some definition of depth between the layers, to the
Hydrochloric won’t actually etch the silver, but will turn it a
sort of smutty off white color (a layer of silver chloride forms,
which is insoluable, and stops further attack by the acid) The
nickle will be etched a bit. Again, I’d try it first with a
pretty dilute solution. Easier to add a bit of acid to increase
the concentration if it doesn’t seem to be doing enough.
Sulphuric will slightly attack sterling if it’s hot, but cold
more dilute solutions won’t touch it much. However, it will
easily attack the copper based nickle silver. This is my guess
for a bright sterling/deeply etched nickle sort of look. As
before, start with dilute solutions (I’d guess 5-10%) and try
For a very slow steady etch on the nickle silver, give some
ferric chloride a try. I don’t know if it will actually work,
but it won’t touch sterling, and on copper it etches smoothly and
evenly. Since nickle silver is mostly copper, I’d expect it to
have some effect.
All the above is based only on general basic knowledge and what
I would expect to happen. I haven’t actually tried etching
nickle silver before. So this is a guess. But I hope it’s of