I know nothing about Violanos, but through the tortuous course of my
life I've dealt with any number of instances in which one or another
object made of cast iron had to be welded because it cracked.  There
may be nine thousand websites devoted to this sort of thing, and they
all seem to say the same thing: sometimes it works, and sometimes it
doesn't.

The problem is that the quality of cast iron is highly variable.
Steinway advertises that they devote great effort to ensure that their
plates are consistent with regard to their alloy composition and are
properly heat-treated.  What this tells us is that in a lot of musical
iron castings the alloys included sand, old sash weights and milk-wagon
axles, and the heat-treatment was that they threw water on it, so they
could go eat lunch.

What a welder will generally try to do is anneal the metal to render it
tough enough to withstand the stresses built up in the welding process
without self-destructing.  This is a lot easier to do if the plate was
made of a good, high-quality gray cast iron rather than surplus grape-
shot from the Spanish-American War.

The other trick is to hammer the stuff while you are welding it, an
eighth of an inch at a time.  Then there's brazing and "bronze-weld-
ing," which are supposed to be different, but don't seem to be.  I
think silver-brazing has been used in tricky situations.

I do believe that there is a new "stitching" process for iron castings.
You could check the Web for it; I ran across it by accident.  They use
a special jig to make holes in the casting, and then pound in things
that are like staples.  I don't think you have to heat it.  I might be
remembering this incorrectly, but it sounds worth considering.

Mark Kinsler
Lancaster, Ohio