Preheating
Using a soft blue flame, move the torch evenly across the surface of the entire article.
Work broadly and keep the flame moving, concentrating the flame on heavier components. Taking this step will ensure that the whole piece is heated evenly, thereby preventing any cold spots from acting as a heat sink. It will also give the moisture in the flux to bubble away and evaporate. Once the flux has settled down, inspect all the components as small pieces may need to be repositioned with tweezers or a soldering pick.
Heating to soldering temperature
The torch should be used with a more intense flame to continue increasing the heat in an even manner. When the correct soldering temperature range is reached, borax flux will take on a clear honey-like appearance. In the case of Tenacity No.5 or Easy-flo flux, the flux will become clear when the soldering point is reached. Direct the heat at the metal, not the solder. Heat from the metal should melt the solder, not heat from the torch. If the metal is not at the correct temperature, then the solder will not flow into the joint. Once the solder does flow, it will do so with a bright liquid flash as it is drawn into the joint by capillary action. The solder will follow the heat and flow towards the hottest part of the metal; if the joint is not hot enough then the solder will not penetrate fully. The torch flame should be removed at this stage to avoid any danger of over heating.
After soldering
Take care to let the silver cool for a few seconds before moving the article. Do not take shortcuts such as quenching in the pickle solution; this will result in unpleasant fumes and the pickle solution may spit as contact is made.
Tips
- Always solder in subdued lighting conditions, this will make it easier to perceive subtle changes in the colour of the metal.
- When heating pieces with uneven weights, concentrate the heat on the heavier item more, otherwise small components may be heated excessively.
- Heating the metal on the opposite side of the joint to the solder will help draw the solder into the joint as the solder flows to the hottest point.
- Just before silver melts, it will take on a liquid, glossy appearance. Once this point is reached the silver may become brittle and take on a dull, pitted appearance as it forms an alloy with the solder. These warning signs can be observed by deliberately melting a scrap of silver far beyond the annealing stage. Learn from this exercise in order to recognise the symptoms when working on real articles.
Troubleshooting
Clean the surface of the metal thoroughly and only use a clean brush for applying flux. Failure to do so can result in excessive fumes being produced and the flux burning away before the soldering temperature is reached.
A torch with insufficient power will be unable to raise the temperature of the components high enough for successful soldering. Novices may be tempted to direct the flame directly at the solder, but this will fail to solve the problem.
