Q: I recently inherited an 82 yr old home. The floors had very old (more than 20 years) carpet on them. We removed the carpet and found the original hardwood floor underneath. In 1 spot there is a large black oily stain.
We tried sanding with no success. Mineral spirits seemed to work but 24 hours later the stain is back. It seems to seep up through the floor and is damp to the touch.
Is there anything other than cutting those boards out and replacing them that I can try?
A: If it is a black stain still seeping up after all these years there is no fixing it. You will have to replace the boards. Perhaps you could take some old wood from a closet to do the patch.