When laser welding Sterling Silver & lower silver bearing alloys (coin silver) we have about seven choices in laser wire.
It takes all the power most lasers have to weld. A magic marker is usually needed for every shot to help initiate the melt. The joints are very pliable and not brittle after being worked. It polishes out of a sizing joint like low carat solder because its so soft its not a good choice for sizing.
The 7.5% copper added to make it sterling is almost as hard to laser weld as pure silver. Its just slightly easier to weld than pure silver. The joints are often filled with porosity even when Argon is used. A magic marker is needed between each shot to help initiate the melt. The joints are usually pliable enough to use for sizing.
It welds nice at high power. The welds look nice, very little porosity. Then when you round up a sizing they break. You need Argon and pulse shaping to size with this wire and not have a brittle joint. So it’s not an option for many lasers.
It welds nice at lower settings than all the other wires. It fills sizing joints easily and isn’t brittle when used for sizing. The down side is its only 60% silver so it tarnishes. When we do a standard V joint it will show a lot after it tarnishes.
It welds at slightly higher settings than the medium solder. It fills sizing joints easily and isn’t brittle when used for sizing. Its about 80 % silver and doesn’t tarnish as bad as the Med solder wire. So its a better choice for sizing.
A Sterling alloy with 5% Platinum was the first alloy that welds perfect. It needs high power also but is predictable and can be pushed deep down into a joint. No Argon or pulse shaping is necessary. When Platinum which is somewhere around 48% reflective is added to Silver it lowers the reflective characteristics of Silver from 90% the highest of any metal to something weldable. Platinum is also a poor conductor of heat and cold. Some of this characteristic is transferred to the sterling. This seems to help impart the characteristic of not spattering. This means less porosity. The joints are very tarnish resistant and very flexible so they don’t crack during sizing. The down side is its very pricey for Sterling I have seen it as high as $ 229.00 an Oz.
A Sterling alloy with 5% Palladium has all the attributes of the Platinum Sterling with out the cost. Its Approx $ 75.00 an Oz. Its my personal favorite for laser welding Sterling Silver. If you get this wire in 26Ga its also an excellent gap filler on sizing and fabrication with no downside because its all solid metal. Got to love the laser.