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andy_b
06-30-2011, 11:22 PM
I know several folks here work with jewelery, or at least those types of materials. I have a piece of sterling silver jewelery (a medallion on a necklace). There is a small hole where a small ring goes through to hold the medallion onto the chain necklace. The hole has worn oval and is almost through the edge of the medallion. I was thinking of filling it with silver brazing solder (like Harris Safety-Silv, since i have a few ounces of it). The hole itself is about 1/16" diameter and the worn section is maybe half that.

I'm guessing a plug shaped to fit the hole made of sterling would be the way to go, and then silver solder that in, but I don't have any pieces of ss just laying around. Also, I'm concerned that the silver solder may want to flow over the medallion, filling in some of the details on it.

So, what would be the suggested method of filling this hole, and what do I use to keep the silver solder from flowing all over?

Thanks,

andy b.

Mcgyver
06-30-2011, 11:42 PM
check this out

http://users.erols.com/jyavins/solder.htm

Silver solder and sterling have such close melting points, if this thing is of value find some other sterling to practice on first or you might just have a puddle instead of medallion. I'd kind of want to give it a try myself, after doing suitable research, because its something i haven't done before....but only if it wasn't important otherwise I'd get jeweller to do it, hopefully telling me how while i watched

Evan
06-30-2011, 11:55 PM
The proper thing to use is silver solder designed for sterling silver. It is very close in alloy but has a lower melting temperature than the sterling. It is available in three grades that each have a different melting point so that a piece can be built up in stages using the highest melting solder first and then the medium and the lowest last.

Try your local jeweler and he will either sell you a piece or maybe give it to you if it is small. You flux it with white brazing flux and to prevent it from running over the rest of the piece you work with the rest of the piece higher than the hole. Clamp the piece lightly so that it won't move and use some mineral board to work on. Use a very low slightly rich oxy/A flame or better is an air/A torch like a Prestolite. You have a couple of hundred degrees room between the lowest melting grade and the sterling. The thin spot near the edge will melt very easily.

The reason to use proper silver solder is because of colour matching. Other types of silver solder will work if you know the melting temp is correct but they will not match the colour.

andy_b
07-01-2011, 12:23 AM
Uh-oh. I didn't realize the closeness of the melting temps. I don't care about color matching (the medallion is always worn under my shirt), but I do care about melting it. :)

Maybe I'll find a small ring of stainless and solder it in with lead-free plumbing solder. At least the plumbing solder will melt well before the sterling does.

andy b.

Mcgyver
07-01-2011, 07:41 AM
if you do soft solder, I believe that will preclude every silver soldering it, will be contaminated. silver solder is 10x as strong and you may need that strength as the area is so small.

Since its important to you, I'd suggest at least find out what it costs before you do something not as good or easily reversed

Weston Bye
07-01-2011, 07:47 AM
Instead of of soldering, why not turn a tiny silver thin wall "bushing" for the hole and flare both ends after installation?

Alistair Hosie
07-01-2011, 08:21 AM
Evan is correct apart from anything else you don't want an obvious repair with two tones of metal ,also please make very sure that the melting point of the solder is lower than the melting point of the workpiece this is very important. I have done much of this work with silver gold and platinum so just take this advice and you should be ok. I would personally advise you to get a jeweler to do it it won't cost much and will be perfect. Alistair

Ken Gastineau
07-03-2011, 04:47 PM
Andy:

A tight fitting plug silver soldered in would work as a repair if you can accurately drill it after after soldering.

Molten silver solder follows heat. To control where the silver solder goes requires accurate use of a torch. A very small oxy-propane torch would probably be required. To further control the flow of silver solder I would use a very small square of sheet solder that is about .030" or .040" square and placed right on the seam of the two parts. If your parts have a tight seam, then the solder will be sucked into this seam through capillary action once the melting temp of the solder is reach. You will need to flux the piece all over before placing the solder square and starting to heat. Even the areas you are not soldering will require flux to help prevent cupric oxides from forming in the subsurface of the metal.

You will also need a mild sulfuric acid bath (pickle) to clean the piece before and after soldering. If there is an antiqued finish then the piece will need to be blackened with an oxidizer before repolishing with a buffing wheel.

If this piece has great sentimental value to you, I would suggest you take it to a jewelry repair professional as it is all too easy to ruin a small Sterling silver piece with a torch. If necessary, repair shops these days usually have access to laser welders that offer even more repair strategies.

Jewelry repair is a specialized field and requires a special touch to get things just right. Believe me when I tell you that things can foul up in a blink of an eye. I have been a manufacturing jeweler for over 30 years and I have not developed all of the skills necessary to work in a repair shop.

Ken

andy_b
07-04-2011, 10:20 PM
After reading all of the replies, and thinking about it, I guess I'd have to agree I may as well take it to a real jeweler. I enjoy the occasional experiment, but this piece would probably not be a good one to use for experimenting. Now to find a decent local jeweler/silversmith.

I do have to say that if I was going to attempt something, Weston's suggestion of a small bushing sounds like an acceptable non-destructive solution.

andy b.

J Tiers
07-04-2011, 10:45 PM
You have decided not to mess with it, so that's OK.

However, in general, oxy-anything is not needed. I did quite a bit of metal sculpture, basically like jewelery, only bigger, think goblet and bowl size. All was done with fuel gas, no oxy.

I've done quite a bit with propane and even butane pen-torches.

The one advantage of an oxy torch is a small heated area, but that isn't the issue here, you need not to melt anything but the solder with a piece such as this (I know "you the O.P." are not going to try it, but....).

There are "low temp" solders that will work, and the standard flat silver solders that you "snip and place". You would want the lowest temp version.

I fact, a couple years ago there was an article in one of the magazines about a watch bow repair using a type I wasn't familiar with that was supposed to be low temp.

biggest hassle with a hot torch like oxy-anything is too much heat. A fuel gas torch should melt the low end solders easily, but not easily melt the silver. You still need to be careful.

Most silver solders (not silver-bearing plumbing solder though) melt in the red hot range, and no matter which one you get it's easy to go too hot and melt something else. if you have three joints close together that you can't do in one go, you have to be very careful with that last one........:D You can do oxy, dash in, melt the solder and go before the other joints know you are there, or use a colder torch and sneak up on it.

Jim Doherty
07-05-2011, 07:10 AM
If the medallion is sterling I wouldn't repair it with anything but hard silver solder which is close to the melting point of the medallion. Why not use a coin holder (goes around the edge and is held together with a screw)

Jim Doherty