Soldering gold

Wife has a gold puzzle ring that is too large for her finger. (Puzzle rings are four concentric bands that come together showing a pattern
on top of the finger).
Her jeweler wants $150 to re-size the rings. Not going to spend that kind of money. My wife says she would be more than happy with a dollop of solder on the bottom inside of the ring to make it smaller. Of course at the same time it would hold the four bands together obviating their falling apart. This could all be done by wrapping dental floss or tape, but not very elegant.
I was hoping to lay a bead of solder on the inside bottom and then file/sand it down to a smooth circular arc.
Questions: Can this be done? Is it non-destructive and reversible? Can gold be soldered easily? Do I use a flux? etc. etc.
Thanks for all suggestions and replies.
Ivan Vegvary
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On 08/04/2012 07:21, Ivan Vegvary wrote:

I'm a working goldsmith (which some people might have deduced from my username) and, amongst other things, I hand-make puzzle rings in all precious metals. If you were in the UK then I could re-size the ring for a lot less than $150, but I assume you're not.
The most important "no-no" is "NEVER USE LEAD SOLDER ON JEWELLERY". Lead solder is nowhere near strong enough, and sooner or later the joint will break and, to make a proper joint with gold solder, *every* scrap of lead solder must first be removed. If it isn't, then the temperatures required for gold solder will cause the lead solder to eat into the gold, rather like mercury does. This will totally ruin the job.
Gold is soldered with gold solder in a process exactly like silver soldering (silver brazing). Gold solder is an alloy of gold with a purity that, in the UK at least, matches the alloy to be soldered. ie. 14K gold is soldered with 14K gold that has a lower melting point than normal 14K gold. The melting point is, typically, around 600-700C. You can use a normal silver-solder flux, or you can get a special flux formulated for precious metals. The special flux can be used straight out of the container - no mixing, saves time.
If you have previous experience with silver soldering, then gold soldering should present few difficulties, but soldering rings presents certain unique problems. The first being that most rings have at least one soldered joint and, unless you are very careful, the previous joint will spring apart when you attempt another one. For an experienced jeweller this is nuisance, but for a novice this is a show stopper. The second is, rings are rather small bits of metal and it is *very* easy to melt the entire ring when attempting to solder a joint. Unless you've done it before, I would advise you to practise a lot before working on anything you value.
The final section is about tidying up afterwards. I would certainly not recommend adding beads or blobs of gold in an attempt to make a ring smaller. Do the job properly. Cut a piece out and solder the joint. After soldering, the first thing you notice is that the ring has gone black, or very discoloured. This is oxide, which must be removed by acid. You then notice that the ring is no longer round, so you must have some method of truing it up. A jeweller will use a ring mandrel, but the chances are that you don't have one. After making the ring round again you will notice that it's no longer shiny, so you will have to polish it, but this should not present any difficulties to somebody who has any experience with metal.
The proper gold solder will not be cheap, but the actual job itself shouldn't be beyond the capabilities of any competent metal worker. But first practise on something you don't mind messing up. IHTH
--
Regards, Gary Wooding
(To reply by email, change gug to goog in my address)
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Wow! What a thorough and thoughtful reply. I thought I could simply take my electric soldering iron and finish the job in less than 5 minutes.
Method described is probably way beyond my skill level. Since 4 bands would need to be cut, soldered, sized and then polished, I can see why they want to charge so much to do this job. Will definitely go with the 'ring sizer' solution described by Gunner, below.
Thank you so much, not just for the advice, but what I have learned about the process.
Ivan Vegvary
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Gunner, Good to hear from you again. Will definitely go the 'ring sizer' route you had suggested. Wife more than happy with that solution.
BTW, you wouldn't have a straight tool holder for a 7" metal shaper? Still would like to go down south some day and see your wares.
Ivan Vegvary (former Californian)
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As Gary recommends, I would also suggest that soft solder not be used.
You don't mention the value of the ring, or how often it's worn. I wouldn't generally recommend applying a plastic/epoxy product to metal, but this may be a good solution in this case.. it would be removable and cause little, if any damage to the ring metals. A really fast, cheap solution would be hot-glue, which could be trimmed for a smooth, comfortable filler.
A different approach could be to use a non-staining metal shim (a strip cut from coin silver flattened into a thin sheet, or a section cut from an old locket etc) and held in place with double-sided tape or an adhesive. The D-S tape strip size should probably be a little smaller than the metal shim to prevent the sticky adhesive from oozing out around the edge of the metal shim. An adhesive that works well on metals, which I've rediscovered recently is named SealAll, which is clear, gasoline and oil resistant and fairly durable.
I've seen ring resizing doodads in the past which are H-shaped (or upper case I) so that the center section serves to make the ring size smaller, and the tabs at the ends are bent to wrap outward and around the ring on the outside. These may be suitable, but definitely won't be if the protrusions are uncomfortable to the other fingers, or if the tabs snag on clothing or other materials. Making a similar piece from flattened coin silver would be a thoughtful project, and if the securing tabs are long enough to meet, they could be filed/polished smooth so they don't snag (or possibly soldered together but not to the ring metal).
Another consideration would be if the attachment would remain clean, or is easily cleaned.
--
WB
.........


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