Another important soldering technique is known as "sweat soldering." This is often used when overlaying one piece of metal on another... like an appliqué. The difference is that you actually melt the solder onto the back of the top piece (after fluxing).

You then pickle and clean the piece as usual.

Then place the piece, solder side down, onto the cleaned and fluxed base. Since the base usually has more mass, it is heated from below, occasionally alternating the heat to the top to help keep everything uniformly hot.

When the pieces reach 1100º, the flux will melt, and the top piece may drop a bit. You now have a couple moments to adjust the position with your pick, if necessary. Continue heating, and the solder will flow between the two pieces. You may see a "wet" line appear around the edges indicating the solder has flowed, or you might see the top piece "drop" as the solder flows.

You have to be careful not to overheat with this technique. It is better to err on the side of caution, then clean and reheat if necessary. If the pieces get too hot (you missed observing the "flow"), the pieces can warp, distort, or even melt. If you overheat the metal, alloys (especially sterling silver) will develop firescale (or fire stain) when the copper content in and below the surface oxidized. It is neither fun nor easy to remove.

TECHNIQUES for JEWELERS

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Author: Dave Sebaste

ArtMetal Editor: enrique

Last Updated: Tue, Sep 17, 1996