LASER-WELDING: 925 STERLING SILVER
By Stuller Standard | August 05, 2011
Handle With Care
One of the most popular (and temperamental) metals to work with, sterling silver presents jewelers with many unique challenges. Pulling soft, delicate stones for a simple sizing may result in dealing with heavily plated silver the torch burns off. Re-plating risks rhodium contamination, and there’s always the chance you may chip or break stones while re-setting. This process can suck the productivity and profit right out of your bench.
Laser To The Rescue
Fear not your task at hand; just grab your Rofin laser, and work your sterling silver the Stuller way.
- Step #1: Cut or prep the metal and re-align the pieces. (NOTE: While preparing the piece, if the metal seems spongy or overly porous, use a ramp-down pulse shape. This will allow the metal to cool more slowly and form a greater bond.)
- Step #2: Use a 3M Scotch Brite wheel or Radial Bristle Brush to remove the shine from the desired welding area. (NOTE: Using a marker to darken the area can work, but is not consistent in drawing the energy into the metal, as a roughed up surface will.)
- Step #3: Set the parameters on your laser, depending on thickness of metal, in the range of 280-300V, 4.5ms, focus 8-18 (NOTE: Very narrow focus can create a hole straight through the metal.)
- Step #4: Fill the seam with sterling weld hard wire instead of 925 Sterling. (NOTE: As the 925 Sterling is very reflective, you would have to use higher and higher voltage to flow the metal. This leads to pitting and cracking the piece. The slightly lower silver content of the silver weld hard will flow at lower voltage and with less splashing.)
- Step #5: Polish your sterling ring and check your nearly seamless repair.
We also suggest with sterling, like costume jewelry, to always start with a test shot at a lower voltage and work up from there. This may take an extra two or three seconds of time, but finding the exact temperature for each piece will make stronger joints in the long run.
Welding Plated Rings
These should not be a problem with this laser repair method. Because the heat is isolated, you will not burn off the plating. After finishing your weld, sand and prep the seam as normal. But when polishing, prevent removing any other plating by only using red rouge. This should leave you with only a small area to pen plate at the end.
[Adapted from the August 08 Stuller Standard]