Does the alum pickle solution give the same fine silver plating
as sparex? (The heat, pickle, heat, pickle thing that you do to
cover fire scale and prepare for reticluation?)
Yes. But you should understand that the white matte silver surface
is NOT plating. Nothing is deposited on the surface by the pickle.
The only thing that happens is that the pickle dissolves the copper
oxides. That's all. In order to get that white surface, you have to
oxidize the copper on the surface for the pickle to then dissolve.
When that happens, any polish on the surface is disrupted, and the
result is that white matte surface. Whether using alum or sparex, if
you put a normally clean unheated piece of silver in the pickle, you
can leave it there till you're blue in the face, but it won't turn
matte white. Same thing if you've heated, annealed, soldered the
silver, but with a good coat of prips flux on it to prevent
oxidation. If there's no black oxide of copper on the surface to be
removed, then there's no resulting matte white surface after