How to repair cracked cast iron with epoxy

Written by c.l. rease | 13/05/2017
How to repair cracked cast iron with epoxy
Cast iron parts are repairable using a metal-based epoxy. (Bench image by Yuriy Rozanov from

Cast iron parts that are not subject to high heat or excessive pressure are readily repaired with metal-based epoxies. Metal-based epoxies are available in either one or two parts. A one-part epoxy cures when exposed to air, and a two-part epoxy needs to be mixed to cure. Both types of metal-based epoxy harden to a steel-like strength that will provide a semi-permanent to permanent repair on cast iron. The permanence of the repair will depend on the cleanliness of the cast iron crack and the proper application of the metal-based epoxy.

Put on your safety glasses and leather work gloves.

Attach the 4.5-inch wire wheel to the 4.5-inch angle grinder and clean the cracked area of the cast iron with the 4.5-inch wire wheel. You need to remove all contaminants, including paint, from the surface of the cast iron.

Wipe the cleaned area of the cast iron with a clean rag to remove the dust created by the 4.5-inch wire wheel. If you are using a one-part metal-based epoxy, apply solvent to the rag and then wipe down the crack in the cast iron.

Mix equal parts of the two-part epoxy until the mixed epoxy forms one solid colour throughout. Skip this step if you are using a one-part metal-based epoxy.

Press the mixed two-part epoxy into the crack or apply the one-part epoxy into the cast iron crack with the putty knife.

Allow the metal-based epoxy to cure for the time specified by the epoxy usage instructions before using the repaired cast iron part.

Things you need

  • Safety glasses
  • Leather work gloves
  • 4.5-inch wire wheel
  • 4.5-inch angle grinder
  • Clean dry rag
  • Solvent cleaner (one-part epoxy only)
  • Metal-based epoxy
  • Putty knife (one-part epoxy only)

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