How to Silver Solder Cast Iron

Silver soldering cast iron is a wise way to repair expensive sporting equipment, tools and the like. Refrain from throwing away a damaged cast iron golf club, for example. Silver soldering will fill a minor abrasion in the cast iron, making it good as new. To pull off a silver solder successfully you need to regulate the temperature. Overheating will result in searing away zinc properties in the silver, which will cause the bond to fail.

Things You'll Need

  • Work gloves
  • Dust mask
  • Safety glasses
  • Solder torch
  • De-burring tool
  • Cast iron brush scrubber
  • Silver solder paste flux
  • Mesh cloth
  • Nickel silver soldering rods
  • Clean, wet rag
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Instructions

    • 1

      Slide on work gloves, a dust mask and safety glasses to protect skin and eyes. Preheat the solder torch, if necessary.

    • 2

      Clean the cast iron surface. Brush miniature cast iron burrs off of the surface using a handheld de-burring tool. Brush with a back-and-forth motion until the surface is burr-free. Rub the bristles of a cast iron brush scrubber on the surface in a circular motion to add smoothness and a natural polish. Find de-burring and brush scrubbers at your local home supply store.

    • 3

      Coat the cast iron surface in silver solder paste flux. Apply the coat with a mesh cloth to avoid fabric hairs mixing with the past flux. Paste flux will expedite the bonding process.

    • 4

      Ignite the torch. Look for a blue flame. Slowly run the torch flame back and forth along the damaged area and the paste until the flame turns green.

    • 5

      Touch the tip of a silver solder rod to the damaged area. Solder with the green flame. Turn off the torch immediately after soldering is accomplished to prevent overheating. Wrap the soldered area in a clean, wet rag to cool the surface and add luster to the cast iron. Remove the wrapping after 15 minutes.