Chain strength

I was wondering if there was any kind of general rule on what style
of chain is strongest for a given diameter? I am looking for an 18K
chain for a lightweight pendant (actually just a briolette and small
pearls) for my mother-in-law. I don’t want to get something that will
break as soon as it is worn, but with the cost of 18K I am a bit
limited on how heavy a chain I can get.

Any thoughts appreciated.
Julia in Toledo.

I prefer basic cable links, round not flat, but stay away from the
featherweights. I have no problem hanging significant pendants from
a properly chosen cable chain, security wise.

As I see it, there are two aspects to chain strength: the tensile
strength of the metal and its resistance to wear. For any given
material, the tensile strength is proportional to the cross
sectional area normal to the applied tension. It doesn’t matter what
the shape of the cross section is, only the area is important: double
the area and the strength is doubled.

The same isn’t true for wear resistance though. Chains wear as the
result of abrasion between the links, and the rate of wear increases
with the pressure per unit area of contact between the links: the
smaller the contact area, the higher the pressure and the greater the
rate of wear. Think about sawing a piece of pipe or tube. Until you
reach the hollow bit the effort is exactly the same as if you were
sawing a solid rod, but when you reach it the saw just zips through.
Its not dissimilar to sawing a wide bar - it is much more difficult
to saw across the wide bit than across the narrow bit. Incidentally,
this is the reason that chains made of hollow wire wear out very
quickly.

For maximum resistance to wear then, you need to make the area of
contact between the links as large as possible, and the type of chain
that does this is known as Venetian Box chain. The links are made of
flat strips of wire bent into rectangles. All other things being
equal, eg. quality of soldering, box chains are the strongest.

Regards, Gary Wooding

I prefer basic cable links, round not flat, but stay away from the
featherweights. 

I didn’t want to get into chain-strength issues, which I don’t know
much about, anyway. From Neil’s perspective, though, we’ve been
using wheat chains for a long time now - strong, double link,
stylish, they don’t kink up if cared for…