14 Soldering tips

Every year I train about 50 people who are brand new to working with silver, gold, copper, and brass. That’s a lot of fresh students to keep track of, especially when torches are involved. I can’t personally help each student make every solder join, so after initial training, I like to give my eager students the following hints for successful jewelry soldering to remind them of what they’ve already learned. Post this handy soldering cheat sheet in your studio and take a peek whenever you need it.

1. Take the time to make solder joins fit tight prior to soldering. Solder won’t fill gaps, and it flows best over a smooth, well-fit join.

2. Work with the highest temperature solder possible. Lower temperature solders don’t blend as well into the surrounding silver. The higher a solder’s melting point, the less alloy it has in it, so the less likely it is to eventually tarnish and show up as a dark seam on your silver. 

3. Don’t be stingy with the flux. Flux helps solder flow, but a thick, even coat of flux beyond the immediate area of your join also helps prevent firescale; more flux isn’t a bad thing.

4. Select your solder shape based on the job. Both wire and sheet solder have their best uses; tailor your choice to the join you’re making. Sheet solder can cover larger areas and lays better on flat surfaces. Wire solder works especially well when you’re soldering bezels to backplates, because the capillary action of the flux pulls small lengths of wire solder so that they line up with the join. 

5. Use a larger torch than you think you should. The tendency is to underheat the metal, which can result in a poorly flowed solder join. If you’re in doubt, select a larger torch nozzle. 

6. Hold the torch with your nondominant hand. This gives you greater dexterity with your soldering pick, allowing you to manipulate the solder and metal more easily.

7. Use a neutral flame. The best flame for soldering is one that you can just barely hear [Illustration B]. A sharp, hissy oxidizing flame [Illustration A] contains too much oxygen, which can increase the chances of firescale. A bushy, loud reducing flame [Illustration C] may not have enough oxygen to be hot enough to solder well.

8. Know your flame. The hottest point of the flame is about 1⁄4 in. (6.5 mm) out from the tip of the flame’s inner blue cone [Illustration B]. If you use flame areas that are further away from or closer than that point, you won’t be heating as efficiently.

9. Keep heat distribution in mind.  Consider the amount of metal in each of the pieces you’re soldering together. If one component is 75% of the total piece and the other component is 25%, spend 75% of the soldering time heating the larger component and 25% heating the smaller component. 

10. Use your flux as an indicator. White paste flux turns clear and glassy at about 1200°F (650°C), just below the temperature at which solder melts. Watch for this change; it’s a good indication that the solder will soon melt and that you’re distributing the heat of your torch evenly.

11. Remove your torch as soon as your solder flows. Watch for the shiny flash of melting solder; when it happens, remove your torch instantly. Overheating your metal can cause it to become brittle or melt. 

12. Always quench your metal in water to cool it before you put it into the pickle solution. This prevents you from walking around with hot metal and from splashing the acidic pickle on yourself. And since the metal is cool when it enters the pickle, less pickle can be absorbed into micro-fissures at the solder join, so the metal is less likely to discolor. 

13. Never put anything iron or steel in the pickle. Iron or steel cause a chemical reaction with pickle that can plate your metal with copper particles. Always use copper or plastic tongs when retrieving your piece from the pickle. 

14. If you can’t avoid firescale, you can remove it or hide it. Firescale can be deceptive; your piece may look nice out of the pickle, but once you start sanding or pre-polishing your finished piece with buffs, it may show firescale. Firescale appears as a dark purple shadow directly beneath the surface of the silver. 

Don’t worry. If you keep sanding or buffing the piece, you will eventually abrade the firescale off along with the top layer of silver, and you can then polish the piece. Alternatively, some artists choose to cover their firescale with a thin layer of fine-silver particles through a process called “depletion guilding.”