Soldering vs. Fusing: Myths of the Trade
How do we make metal stick together? Well, there are actually a couple of solutions. The most widely practiced is soldering. Solder is a metal alloy that has a lower melting point than the metal it is used to join and no structural strength; it relies on the edges of metal touching each other to create a connection. The advantage to using solder is that metal can be joined without bringing the gold around it to melting temperature, which reduces the chance of melting the actual jewellery, and of drawing porosity and other impurities into the gold. The disadvantage is that the join created is weaker than a solid piece of gold, and that solder is an irritant to skin. Having said that, a well-soldered join is likely to last a long time. If every place that solder is used with is properly shaped and cleaned only a little solder should come into contact with skin and it shouldn’t cause irritation for most people.
Fusing is the act of melting metal into metal, creating one single piece. Fusing is a less common practice in the jewellery world, because it is more difficult, uses more gold, and because there are risks involved in bringing finished pieces to their melting points. The big advantage of fusing is that it provides solid strength and durability so you can be sure it will never fail.
Because we hand form all of our pieces we fuse our joins while our pieces are in the creation stage. This ensures that the entire piece has the strength of solid metal. After a piece is created, it is acceptable to solder one or even two joins in the act of resizing, but a band with more than two solder joins creates weak spots and makes future work on the piece risky. This is one reason why after a band has been sized a few times, especially if it is made larger, it is good to do a half shank, which replaces the whole bottom of the band with one solid new piece of gold.
At Hubbell Designer Goldsmiths we will often fuse metal when sizing rings if we feel we can do it safely, and any time a ring is brought to us that already has solder joints, we will do what is necessary to make sure the ring is still strong even if it takes more time than simply soldering in another piece.
Claw tipping on diamonds is an ideal time to use the soldering technique, as using solder means that the diamond does not need to be heated as much to accomplish the join. Diamonds can withstand the heat required to melt solder, which is why it is possible to re-tip claws on diamonds without removing them. Some stones cannot stand heat at all, and must be removed and reset after new tips are added. In that case we can often fuse them on, and that results in a longer life for the claws.
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