How to Repair a Hole in a Cast Iron Pipe With PC-Metal Epoxy

Purchase an unfinished wooden dowel small enough to fit inside the pipe but large enough to block the hole from the inside.

Use a metal file to remove any rust from the edges of the hole in the pipe. Wipe away the rust powder with a damp rag. Dry the pipe with a towel.

Soak the dowel in water; this will keep the epoxy from sticking to it.

Insert the dowel into the pipe. Position it so you can see the wood through the hole in the side of the pipe.

Wet your fingers with cool water. Mix a portion of PC-Metal plumber's epoxy putty according to the manufacturer's instructions. Make about ¼ tsp of mixed putty for every square inch of hole you will patch. Re-wet your fingers as needed while you work with the putty.

Roll the epoxy putty into a ball in your fingertips. Pinch it to flatten it into a sheet about 1/8 inch thick.

Lay the sheet of epoxy putty over the hole on the outside of the pipe. Trim the excess putty from the edges using the craft knife; remove putty that isn't covering the hole and leave just enough putty to overlap the edges of the hole by ¼ inch.

Smooth and press the edges of the putty with your fingertips to blend it flat against the pipe.

Wait for the putty to cure fully according to the manufacturer's instructions.

Mix some plumber's epoxy glue according to the manufacturer's instructions. Make the same quantity of mixed glue as the quantity of putty you used. Stir the glue with a craft stick.

Use the craft stick to spread the epoxy in a thin layer over the putty patch. Extend the glue slightly beyond the edges of the putty.

Let the epoxy glue cure according to the manufacturer's instructions.