Can I solder broken costume jewellery?
I receive lots of enquiries asking if I can repair pieces of broken costume jewellery. Often, such repairs require the use of soldering. In this article, I explain why I always look for an alternative way to repair the item.
Soldering is a process that requires heat… lots of it! It involves melting solder, an alloy containing two or more metals that have a lower melting point than the metal in the pieces you want to join together. The molten solder must flow into the join and form a bridge between the two parts. Once the solder cools, it creates a solid connection between the two pieces.
Why can’t I solder costume jewellery?
The reason I don’t attempt to solder costume jewellery is because of the way it’s made.
Costume jewellery is made from mixtures of non-precious metals. Depending on the mix of metals used, the melting point will vary significantly. That means I can’t predict how they might react at high temperatures. For example, some vintage pieces are made from mixtures of tin, lead and zinc (known as pot-metal) which melt at relatively low temperatures. Trying to solder an item of this nature is likely to lead to a serious melt-down!
When you heat metals in the presence of air, they often discolour. On raw metals surface discolouration can be polished away, or removed chemically. Costume jewellery usually has a gold or silver plating over the base metal, and removing discolouration may remove that plating as well.
Costume jewellery often contains rhinestones. Rhinestones are generally made of glass with a foil backing to make them sparkle like diamonds. They can shatter under intense heat. Prong-set rhinestones can usually be removed from their settings without the foil backing being damaged, but this is not the case with glued-in rhinestones.
Would you like to see what happened when I did a soldering test?
I chose two mid-century bracelets with broken soldered connections for my test. Each was made from a base metal cup-chain, with larger rhinestone settings soldered between. In this picture you can see the broken connections that I wanted to repair. You can also see metal discolouration caused by heat from the original soldering process.
First, I removed the closest rhinestones, cleaned and prepared the surfaces to be soldered. From their age, I assumed these bracelets were made with a lead-based solder, so I worked in a well-ventilated space outside. I chose a low temperature soldering method for my test, using tin-based solder and an electric soldering iron.
The solder adhered to both of the settings individually, but I couldn't get a bridge to form between them. Imagine my dismay when the heat conducted through the metal setting melted the solder on its other side. It fell off!
And when I tried to reattach it, the heat caused the second setting to fall off as well… DOUBLE OOPS!
I couldn't form a soldered join on the second bracelet either, until I used a tiny strip of adhesive copper tape as a base for it. You can see the tape in the picture below.
I was worried about the tape peeling off and taking the join with it, so I had to cover it really well.
So, in the end, one bracelet was further damaged by soldering while the second was roughly repaired. The metals and alloys in each bracelet reacted differently to the temperatures used, and the results were not all positive. While a soldering expert might be able to achieve a better outcome, it confirmed my belief that this technique is not suitable for use on costume jewellery.
So that’s why, when I’m asked if I can repair a treasured item of costume jewellery, I look for ways to do so that don’t involve soldering.