There are many myths about heating pieces during soldering that can cause innumerable problems during relatively simple soldering operations. In this occasional column, I will address the top soldering myths and the essential criteria to be used in evaluating soldering techniques.
Nearly every book and article about soldering concepts contains this myth. Even The Theory & Practice of Goldsmithing by Prof. Dr. Erhard Brepohl includes this myth: “When using jeweler’s solder, it is always necessary to heat the entire piece.”
His book is my favorite, and by far the most useful jeweler’s reference that exists. I assign it to all our apprentices because concepts are explained in detail, and scientific data is provided to prove and illustrate all concepts. The only exception to this is the aforementioned statement. There is no data to support that the statement is accurate or even a description of what negative effects could be expected if the advice was ignored. This prompted me to test this theory for myself.
For years I tested and retested on fine and sterling silver as well as 14k to 22k gold, and on pieces ranging from very small earrings, pendants, rings, and pins up to large, thick cuff bracelets. What I discovered is that it is not necessary to heat the whole piece to get solder to flow successfully on typically sized jewelry pieces. The only exceptions I have found are very large flat pieces that may expand and contract out of alignment if heated in just one spot and are best fully supported if this method is used. (I use a screen set up on a tripod.)
For solder to flow successfully, the entire seam you are intending to fill must get hot. But that doesn’t mean the entire piece needs to be heated. This is a critical difference and changes everything about what method to use while heating. Solder will flow to the hottest area of the piece first. You can’t get your seam hot enough to solder while you are going around and around the whole piece; too much of the heat will dissipate. Instead, keep your torch positioned near the seam you are trying to fill.
You’ll be amazed at how quickly and beautifully the solder flows when you aim the heat at the place you are soldering rather than circling around it. My pieces suffered no ill effects from not heating the whole piece, such as solder seam breakage or failure. In addition, this method cuts down on the formation of oxidation, an important benefit for quick and clean solder flow.
This article is excerpted from “Soldering Demystified,” a paper presented at the 2015 Santa Fe Symposium on Jewelry Manufacturing Technology. To order a copy of the paper, visit santafesymposium.org.
Jeanette K. Caines is the director of Jewelry Arts Inc. (jewelryarts.com) in New York City, and the author of Soldering Demystified (available on Amazon).