Remove rot from center of tree stump

Question

I have a large tree stump that I am going to polyurethane to preserve. The center of it is rotted.

I've dug out what I could of the rot with a shovel, drill, and vacuum.

Looking for advice on what I can do to remove the rest of the rot.

The size of the rotted area is about 1.5 ft diameter and 2' deep. The stump is 4 ft diameter.

I'm doing this to remove any moist material and give a surface that I can polyurethane.

An alternate method would be to pour something in the middle to preserve it but I don't know what that something would be. It's important that stump doesn't split under thermal cycling.

Any thoughts and advice appreciated.

Answer 1

You need to soak it with some fungicide to stop the rot. Things like polyurethane seal a surface but the fungus is inside. Although as large as it is with one side sealed from moisture , it will take many years to rot. In 5 years a 30" pine stump with no protection has only about a 5" diameter hole rotted in it, and that is in a warm ( zone 8 ) climate.