The durability can be different, however we have examples if
Viking cast fine silver jewellery, that is still as good as the day
it was cast.
Just because something is cast does not mean it won’t last. It
might. And you don’t know that those viking pieces were used a lot
either. However, if you compare two identical pieces, one cast, the
other fabricated, under identical conditions of use ans wear, the
cast piece will not do as well. How large the difference is can be
variable of course. And as has been noted, some hand made work is
still garbage, while some cast work is high quality. But as I said,
two otherwise equal in quality pieces, one cast, the other made from
rolled, drawn, forged, metal, if compared, will show a clear
difference.
Work hardening and refining the grain of any metal makes it more
durable.
Yes, but the degree of work hardening you give a casting is minimal.
Grain refining and heat treating for hardness can only go so far.
There are some exceptions, of course. Heat treatable platinum, if
cast and properly treated, may end up harder and more durable than
fabricated iridium platinum. But here, of course, you’re comparing
two different alloys.
How durable does a piece of jewellery have to be. A pendant would
not need to be as durable as a ring (that is worn on a daily
basis). If a ring is an accent, then in theory it would only be
worn on special occasions and not subject to wear.
How durable a piece needs to be is not relavent to the comparison.
It is, of course, a critical part of any design process, and many
cast pieces may be made so as to meet their design paramaters for
durability. The difference, again, is in comparing otherwise
identical pieces.
One of the points that came up was that a cast ring will have a
different surface finish to a hand made ring.
Any casting will have some porosity. Good quality castings will have
that porosity be on such a small size scale as to be not
objectionable or visible without a microscope, and with some cast
metal, high magnification or sophisticated equipement may be needed
to see or measure it. But it’s there. Casters can refer to their
castings in terms of their density. It’s common for castings to have
a density a few percent under the theoretical density of that metal,
simply because the porosity lowers it. Once forged, rolled, drawn,
etc, metal density generally will be nearly or actually the true
density of that alloy.
As to surface finish, that density of the rolled, drawn, forged, etc
metal will make it possible with proper polishing, to get the highest
possible degree of finish for that metal. Lower density porous metal
will simply not allow exactly the same. Whether the difference is
enough to see, depends on the situation. And some forms of processing
of a casting, such as steel shot tumbling or burnishing, or anything
else which is working and compressing the surface of the metal, will
result in metal that, for finishing purposes, is the same as forged,
rolled, drawn, etc, simply because that surface skin is indeed such
metal.
Add to this, issues of grain size. In some castings, the grain size
may be quite large, and sometimes this can lead to an orange peel
surface when polishing. Proper casting methods usually can help
eliminate this, and with some metals, it’s also possible to cause
such problems, usually by over annealing, or over working, the metal
while fabricating. Still, the problem seems a bit more common with
castings.
Peter Rowe
Thanks for sharing.