121 Solder Zinc Plated Steel to Brass Tubing with Super Alloy 1 Multi-Metal Solder
Zinc plating is a process in which a base metal is coated with zinc. Also known as electroplating, applying this zinc coating to metals such as steel provides superior corrosion and rust resistance. Steel, for example, is first immersed in a chemical solution of zinc, then a DC electrical current is used to create a thin zinc protective coating. The zinc coating is shinier and more durable than the original steel part.
For this demonstration, we inserted a piece of brass tubing into a piece of zinc plated steel. We used sandpaper to thoroughly clean both metals prior to soldering, to ensure the filler rod would bond properly.
Once the parts were prepared for solder, we then used a propane torch to pre-heat the metal gently, applying more heat to the steel than the brass, since brass has a lower melting temperature. Ideally, both metals will reach the 350°F working temperature at the same time.
As you can see, Super Alloy 1’s liquid flux changes from golden colored to root beer brown when the metals have reached working temperature–even plated metals. This transformation indicates it’s time to apply the solder rod. Alternate between solder and flux, continuing to broadly heat both metals. Always keep the torch moving to avoid overheating the flux, brass, and/or plated steel. If the flux turns black, remove it with warm water and a wire brush and begin again.
We recommend adding a bit more flux at the end, simply to flow out any lumps. This step will create a smoother aesthetic appearance to your zinc plated steel brass joint.
Always air cool the part after soldering, and remove any excess flux as directed above. The end result is a 20,000 psi bond.
In addition to steel and brass, Super Alloy 1 low temperature solder bonds to copper, pot metal, galvanized metal, bronze, aluminum, zinc die cast, pewter, zamak, monkey metal etc with nearly any torch.