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Question:

I received a quote to have my floors sanded and refinished with 3 coats of polyurethane (oil). When one of the workers came to put on some finishing touches he remarked that the floor had been done with water based polyurethane. I have not paid for the work yet.

What is water based polyurethane? It is as durable as oil based polyurethane? What is the cost difference between these two products? Should the cost of having three coats of water based be the same as three coats of oil based?

Answer:

Dear Sheri

The answer is, water based finishes can be better or a whole lot worse than the standard 3 coats of oil modified polyurethane. Let me explain. The few reputable brands of catalyzed and oxygen cross linking water based finishes should be as durable (ox. cross linked) as the OMU. And there should be no doubt that the professional catalyzed water based finishes will outlast most all other finishes by a long shot.

The cost of these finishes mentioned above would be the same (for only 3 coats) or more than the OMP. Some of the catalyzed water based finishes are really expensive.

But now there are the brands that are sold in stores. They are generally the weak kneed acrylic based finishes, with no hardener additive. These are not really floor finishes, but just light duty wood finishes, and are generally sold as such. These tend to last only a few years at best. These are cheap to apply, but are not worth anything in the long run.

That said, my greatest objection to the water based finishes is their pale bluish white film, and the fact that some will cloud more when they age. But if you read my article in the Floored News, about the Dura Seal 1000 water based finish, there is the promise that these oxygen cross linking formulas have the best of both worlds. If you use 4 coats of this material, and scuff sand well between coats, you should have a finish that will wear about as well as OMP and will have a pleasant amber tone to it. We still don't know just how well this finish is going to age, only time will tell. There is some concern that the emulsifiers in all water based finishes stay in the film and make the finish opaque in just 3-5 years. I saw a job done with a store brand water based finish on maple, and this was happening after only 3 years. It was such a gradual change that the owner did not see it, but the fine grain of maple was just about obscured.

So you should find out what brand of finish they used. I'd say if it the same as or similar to the Dura Seal 1000 and they are willing to do one more coat, it may be a good and maybe great finish. But only time will tell. And if is one of the professional catalyzed water based finishes and they apply a forth coat, (again because of the low build) you will have a pale and paling finish that is quite, quite tough.

But if the floor has been finished with a store brand non catalyzed water based finish, it will be best to have the floor sanded over again and apply 3 coats of OMP. This is what I still use on 90 % of my floors, with great (20 years and counting) results. Just be sure they use no lacquer sealers. And have them Brush on the coats of OMP for a real bubble free finish. I just finished a rough draft on how to use the Oil Modified Polyurethane for the directory subscribers, and believe me it is not a quick and easy process, but worth it.

Oh, and if you are going to have the floors re-sanded, you should be compensated for having 1/6 of the total life of your floor sanded off unnecessarily.

As always your Most humble servant, Joseph, the Wood Floor Doctor.

You may also find these articles helpful:

1. Floor Types And Finishes

2. How To Apply Oil Based Polyurethane WITHOUT The Pits And Bubbles

3. Custom Staining Wood Floors Without The Blotchy Effect

4. Laquer Finish Floor Fires

5. How To Take Care Of Your Health And Safety when Installing, Finishing, Repairing or Cleaning your wood floors