a problem with soldering... and a torch question.

Yesterday i was asked to solder closed the decorative "jump ring" on a
silver pendant. It was pretty daunting because the owner told me how much
the pendant was worth before I started work on it, but I got through anyway.
I cut up a potato and embedded the pendant in the potato to protect the
silver bezel, and the facted stone. I just left the ring mount and jump ring
outside the potato.
The jump ring was made of a thin sheet, and when curved into the ring shape,
could best be described as triangular. (I'm sure there's a name for these
things)
The problem, due to the expense of the pendant, I used the potato (and some
"cool paste" to protect the pendant, but then had problems getting the
solder to wet the jumpring nearest to the pendant.
I straightnened the jumpring out flat, and "tinned" both ends of the ring,
and then shaped it into the curve. I fluxed (easy flo) and I never seemed to
be able to get the sodler to wet on the side nearest the pendant. I tried
tipping the ring for gravity assisted flow, and I tried moving the liquid
solder with my solder probe... nothing seemed to work.
I'm very confident the ring was clean in that area since I filed it, and
used liberal amounts of flux. I was using "easy" silver solder.
I presume the problem was due to the potato taking the heat away from the
ring, but if it was that, how else can I protect a $3,000 pendant?
I ended up with a satisfactory joint by using a lead solder to sweat the
silver ring, and then filed back so it's not visible.
Any advice here?

A question on torches... How long, and approx diameter are the "flames" on
one of the "little torches" used by most people (the one with the oxy-acet
bottles)? I've seen blue cones as small as 4mm long, by 1mm diamter on a
standard oxy set, so I was wondering how such a small flame compares to the
flames used in soldering jewellery.
My Primus (propane) setup has a flame of 25mm length, and 2mm diameter and i
worry it may be too big.

The rest of yesterday's jobs were simple repairs, replacing boltrings,
straightening parrot clips, and 1 new jump ring. I was quite confident in
those repairs, but the one above took over an hour of retrying over and over
again.

Thanks,
Des

"Des Bromilow" wrote in message
...
Yesterday i was asked to solder closed the decorative "jump ring" on
a
silver pendant. It was pretty daunting because the owner told me how
much
the pendant was worth before I started work on it, but I got through
anyway.

You know, I come across people that are convinced (because 'someone'
told them), that their CZ stone is a diamond, and you being a jeweller
just can't convince them that it's not, and even if you told them all
the correct info they still won't believe you. I had a chap call in
the other day and he'd bought a 'second-class diamond ring' when
holidaying in Tunisia. He'd paid around UK£60 for it thinking that it
was a diamond and a good deal. sigh. It *was* a CZ, (and the worst
one I've ever seen, as it had chips on several facets). He'd bought it
as an engagement ring for his girl as a surprise. D'oh! The gold was
stamped '590' - oh yes, '590', (never seen that before myself...) The
buyer was told that it was 18ct gold. Hmmm...

Don't believe everything you hear from customers. You mention below
that this 'silver' piece is worth around $3,000. If this is the case,
then it has a diamond (or something else), that's worth $2,980 set in
it. Possible, but probably not the case.

I cut up a potato and embedded the pendant in the potato to protect
the
silver bezel, and the facted stone. I just left the ring mount and
jump ring
outside the potato.

I like this idea, but, to me, I see faults in it. For instance,
*if* I did this, then I would expect 'most' of the pendant to at least
'warm-up' inside the potato. The result? Some (unseen) steam rising to
cool your join down, or at least, *too* cold. Potatoes are 'very' cold
when fresh.


The jump ring was made of a thin sheet, and when curved into the
ring shape,
could best be described as triangular. (I'm sure there's a name for
these
things)
The problem, due to the expense of the pendant, I used the potato
(and some
"cool paste" to protect the pendant, but then had problems getting
the
solder to wet the jumpring nearest to the pendant.
I straightnened the jumpring out flat, and "tinned" both ends of the
ring,
and then shaped it into the curve. I fluxed (easy flo) and I never
seemed to
be able to get the sodler to wet on the side nearest the pendant. I
tried
tipping the ring for gravity assisted flow, and I tried moving the
liquid
solder with my solder probe... nothing seemed to work.
I'm very confident the ring was clean in that area since I filed it,
and
used liberal amounts of flux.

Too much flux can hinder your soldering.


I was using "easy" silver solder.
I presume the problem was due to the potato taking the heat away
from the
ring, but if it was that, how else can I protect a $3,000 pendant?
I ended up with a satisfactory joint by using a lead solder to sweat
the
silver ring, and then filed back so it's not visible.
Any advice here?

Yes. You've just managed to reduce that price significantly by
using lead solder on a quality piece, (if indeed, that is the case).
Lead solder is a big no-no when it comes to precious metals. It just
sinks into the metal when it gets too hot if using a flame. Assayers
won't hallmark it, and would probably chop it into little pieces
before returning it to you. (Well, they used to, I don't know about
this today).

This is what you should have done: Forget the potato, and forget
the 'Cool-Paste', and forget any other cooling procedures too, (for
this job, at least). Heat the join with your 2.5" flamed propane torch
very quickly, and at the same time, dab a little 'easy-flo' on the
join and then apply your solder when coming up to cherry-red, you can
almost do this at the same time, it's that quick, (do this in a
darkened section of your workspace, turn lights off). The heat, when
done properly, won't go near your stone. *Practice on lots of
different sized jump rings first*.

If the stone is a real problem, then unset it before soldering. You
can then take your time to get it right, and then re-set your
un-damaged stone.

Hope this helps...

Regards,

-SP-



Thanks,
Des