122 How to Solder Steel to Pot Metal with a Propane Torch
Now you can solder steel to pot metal at 350 degrees using a propane torch and Super Alloy 1 multi-metal solder rod and flux. This technique is especially useful in restoration projects, when it may be necessary to join dissimilar metals–like attaching a steel screw to a pot metal emblem.
To solder steel to pot metal, begin by removing all oxidation from both parts. This can be achieved using any type of abrasive material: sandpaper, Dremel tool, wire brush etc. Be sure to remove all impurities thoroughly, as oxidation can interfere with proper bonding (causing pinholes or porosity in your solder).
Next, apply heat to both the steel and pot metal with a propane torch. Keep the torch moving, broadly heating both metals to prevent overheating and melting the low temperature base metals. For this application, we heated the pot metal from below.
Dip the solder rod into the flux and apply it to the joint of the steel and pot metal. Continue broadly heating until the flux changes color. Root beer brown indicates it’s time to add the solder rod. Black means you’ve overheated the flux and will need to remove the burnt flux with warm water and a wire brush (no problem!!)
Notice the technique: he tins the surface by slowly adding a small amount of solder to the pot metal, followed by flux to flow the material completely.
We cooled the part quicker than normal for the video but would always suggest letting the part air cool. Excess or residual flux can be removed as noted above, then the part can be reinstalled.
Super Alloy 1 can solder steel to pot metal as well as:
- zinc die cast
- monkey metal
- galvanized metals
All these metals can be soldered either individually or in any combination, with Super Alloy 1