Sweat soldering is a simple and fuss free way of joining two metal surfaces together, one on top of the other. It is great for flat surfaces and ideal for seams, where neat solder application would otherwise be tricky.
What is Sweat Soldering?
Sweat soldering jewellery is a two part process whereby solder is melted onto one surface, cleaned, positioned and re-heated to join a second surface.
As the metal reaches temperature, the solder floods or ‘sweats’ between the layers of metal, forming a strong and neat bond with no excess.
Providing everything is flat and grease free, sweat soldering produces neat seams which require only minimal cleaning, thanks to the bulk of the solder being hidden from view.
How to Sweat Solder
There are a few golden rules to remember as with all soldering, but sweat soldering is an easy technique to master and is suitable for all skill levels.
Step by step sweat soldering:
Sweat soldering: preparing your metal and solder
- Make sure both surfaces to be soldered are flat and grease free. Sheet should be annealed and flattened using a mallet and a flat stake, whereas wire or anything with a curved profile should be very slightly flattened, using emery paper to provide a little stability and grab.
- Check your pieces fit together as flush as possible with no gaps, and rub over with emery paper to give them a final clean.
- Take your top piece (or smaller piece) of metal, and apply a layer of flux to the underside. Place onto a heatproof surface flux side up.
- Using tweezers, apply tiny pieces of hard solder onto the surface, positioning them towards the edges.
Now for the sweat soldering technique
- Now gently heat the metal, keeping the flame moving at all times to bring the temperature up evenly until the solder flows. As soon as this happens, remove the flame.
- Allow the piece to cool, quench and then pickle until clean.
- Once clean, use coarse emery paper to rub over the soldered surface to make it a little flatter. This will enable it to sit better on top of your second piece of metal.
- Next, apply flux to the top of your base piece and the underside of your top piece – in other words the two surfaces you want to join directly together.
- Put your pieces into position on your heatproof surface, with the solder sandwiched between the two layers.
- Heat gently, allowing the flux to bubble and reposition pieces if necessary.
- Now apply the flame directly to both pieces, keeping it moving but concentrating on the larger piece to bring both up to temperature at the same time. As the metal starts to glow red, the solder will start to flow.
- Heat will draw the solder towards it, so guide the solder along the seams if you can see any gaps. Check the joins are all complete and remove the heat.
- Cool, quench and pickle the piece.
This sweat soldering technique produces beautiful neat seams and providing you have followed the steps above, your work should now only require minimal cleaning up. If you do find any gaps, simply clean, apply a liberal amount of flux and re-heat and this should rectify things.
Once mastered, sweat soldering will become one of your go-to techniques of choice. It is strong and efficient, and saves hours of clean up time so what’s there not to like?
If you would like to learn more about the basics of silver soldering before attempting sweat soldering jewellery, take a look at this blog post to discover the essentials you need to know. Why not try soldering a ring band together too?