Pot Metal Brazing Techniques: How to Repair an Antique Buick Grille with Super Alloy 1
Pot metal is an inexpensive alloy comprised of any combination of zinc, magnesium, cadmium, lead, iron, copper, aluminum and tin. Many classic car parts were manufactured from pot metal (also known as white metal, monkey metal, or zinc die-cast) due to its inexpensive cost and quick & easy casting properties.
Historically, many of these parts have been discarded with age, simply because pot metal’s low melting point (786°F) has proven difficult to repair. With a melting point of 350°F, Super Alloy 1 is the rod of choice for soldering pot metal, enabling classic car enthusiasts to effectively repair pitting, cracks & broken pot metal castings.
This antique Buick grille had both a hole and a break in the pot metal and was in need of restoration.
After using a sanding disc to clean the contaminates and oxidation from the work surface, Super Alloy 1 rod and flux were used to for both repairs.
Begin by dipping the solder rod into the flux and applying the flux to the repair area. Be sure to heat the area from the backside of the repair to allow the parent metal to gradually reach the proper working temperature. Notice the flux’s change from honey gold to root beer brown. This transformation is an exact temperature guide, indicating it’s time to add the solder rod. If the flux turns back, stop heating and remove the burnt flux with warm water and a wire brush, then begin again.
For this repair, use a tinning technique–move the rod around the hole to fill the hole and build the solder onto itself. Continue adding more solder until the hole is completely filled with no low spots, then flatten the solder with a wood piece. The resulting repair can then be sanded down and chrome-plated.
After filling the hole in the pot metal, Heat Freeze Heat Paste is applied to eliminate re-melting the solder while working on the broken piece.