Step 1: Remove the White Rings

Wood stains fall into two categories: White rings and black marks. Both are caused by water. When it’s trapped in the finish, it’s a white ring. When it gets a chance to penetrate into the wood, it's a black mark. The white rings aren’t so hard to take care of. Use a pad of very fine steel wool and drench it with lemon oil. The lemon oil won’t remove the stain, but it lubricates the steel wool so that it doesn’t scratch the wood.

Very gently buff out the white ring with the fine steel wool.

Step 2: Remove the Black Rings

Black marks can be rubbed all day, however, and they’ll never come out. The only way to remove them is to remove the finish and then attack the stain. The problem when trying that with a fine antique? By taking off the finish, the value is lowered. On the floor, though, that’s not an issue. In fact, putting a new finish on a hardwood floor actually increases the value of a house. Here’s how to do it: First sand the finish off the wood. Then attack the black mark with bleach. Use a glass jar and an old brush. Pour the bleach into the jar, dip the brush in the bleach, and brush the bleach onto the stain. Let the bleach evaporate for a couple of hours and then come back and apply another round. Let it sit overnight.
If the stain still isn’t gone, step up the efforts with commercial wood bleach. First, moisten the wood with a damp sponge to allow the bleach to penetrate better. Then mix equal amounts of the two liquids that come with commercial wood bleach. Brush a liberal coat of the mix on the damp wood and let it soak into the wood. In a little while, it should start bubbling. It takes about four hours to see results. Then make sure to neutralize the bleach. Mix two parts water to one part ordinary household vinegar. Dampen a sponge with the mixture, and rub back over the bleach.