Your wood floor finish needs to be freshened up. How do you re-finish your floor with oil-based polyurethane?

A Little Floor Finish History

The most commonly used early oil-base finish was varnish. Once applied the floor required a wax coat to keep the floor water resistant. Varnish looks like today’s polyurethane.

Since, you are are freshening the existing finish and not sanding down to the bare wood, you will test the floor to make sure there is no wax or contaminate on the existing finish.

Test the Finish

My way of checking is to simply pick a spot and spread a little bit of polyurethane on the existing finish and wait for ten minutes. Be sure you have some paper and a little paint thinner at the ready.

If the floor finish “fish eyes” then, the finish is contaminated. A fish eye  will look like a light depression in the floor finish. It will have smooth rounded edges and a concave center.

If the polyurethane just sits there, your good to go to the next step. Be sure to sop up the polyurethane you poured for the test with the paper towel and paint thinner.

Prepare the Floor

The next step is to break the seal on the old finish. This light sanding does not take you down to the bare wood, but screens the finish, so the new coating has something to adhere too. You’ll need to rent two sanding machines: a large machine for the floor and a smaller machine for the borders.  Rent only quality sanding machines at a reputable floor refinisher for the best result. By the way, skipping this step guarantees certain failure.

After you have finished doing your prep work, you can move on to vacuuming the area. Next, you will tack the floor because it’s still not clean enough for the coat of finish. There are so many ways of doing this - an old towel with paint thinner -  paper towels - tack rags you can buy at the store . It’s always a good idea to remember your dealing with combustible products and to treat them like that . Follow the manufacturers recommendations.

Remember the better you clean your floor, the cleaner your coat will come out.


Next, apply your polyurethane. But, take into account this is an oil base product and plan on how to dispose of your applicators upon completion, or you can clean them, if you wish.

We will use a 10 inch paint pad and a 6 inch paint pad for application. You will want a paint pan to pour your polyurethane into and some rags should it get away from you. Pour a little polyurethane into the pan. Then dip your 6 inch applicator into the polyurethane and going with the grain apply a modest amount on the floor along the wall. Then on one end repeat by going about 3 feet.

Using your 10 inch applicator dip it into your polyurethane and spread it on the floor with the grain. Again putting on a modest layer but not to heavy. When you get close to the other side of the room. Take your 6 inch pad and repeat the application you did on the other side. Then repeat until the whole room is coated. Let dry overnight.

If another coat is needed repeat the steps and apply another coat. This can take as long as a month to cure depending on the product. Check with the manufacturer for cure times.

Now enjoy your beautiful floors. Hope this helped.

~ Floorman