How to Apply Polyurethane Finish

Quality natural bristle brush.
A quality natural bristle brush works great for applying oil-based polyurethane finish.

How do I apply polyurethane without getting bubbles? Is it better to apply with a sponge brush or a bristle brush? -Michael

Hi Michael,
I prefer a high quality bristle brush, though a sponge brush works pretty well and has the advantage of being disposable. Make sure the temperature of the project you are finishing, along with the can of finish itself, are within the range specified on the can, and that both have had adequate time to adjust to it.

Don’t shake the can. Instead, stir the finish slowly until it is mixed well. Whenever possible, apply the finish to horizontal rather than vertical surfaces to prevent runs.

Apply the polyurethane evenly and smoothly, overlapping your brush strokes to keep a wet edge, and don’t go back over the finished work once it has begun to dry. If you notice a bubble while the finish is still wet, try popping it with a pin.

Good luck with your project,

Danny

11 COMMENTS

  1. Hi Danny,

    We recently had our hardwood floors in our new home screened and recoated with a polyurethane finish. Now, they look great except for any deep scratches that were present before now look even more noticeable! How can we fix this!?

    Thanks,
    Alison

  2. I recently sanded and stained my hardwood floors. After applying polyurathane the floors turned a white milkfish color during the drying process. What did I do wrong? The stained dried for 3 days. Please advise!

    • Tony,
      When polyurethane turns a milky color, it’s usually due to too high a humidity when it was drying or a bad batch of finish. You can try wiping mineral spirits or denatured alcohol over it to see if it will draw the moisture out of the finish. If that doesn’t work, your best bet would be to strip it and start again with new polyurethane.
      Thank you for your interest!

  3. So im building a farm table for my kitchen and made it to the clear coat stage and now the clear coat doesn’t want to cure completely. It has been drying for 8 plus hours now and the room temperature is roughly 56 degrees Fahrenheit. Please help? Is it to cold? I stirred properly. Thanks!

    • Stephen,
      You would need to see what the finish manufacturer says about the recommended application temperature for the finish, but 56 degrees seems mighty cold to me. At the least it will make it take the finish a lot longer to harden.

  4. We just had stairs and railing put up in our house. I used wood conditioner on them and stained them. I wish I wouldn’t have used the conditioner but it’s done. I used a polyureathene on them ( water based) but it didn’t say it was for floors. I want to re-do the poly using one specifically for floors what do I need to do? Do I have to take all the old off? The new stuff is also water based. If I sand them down a little can I put on more stain before I put on the new poly? I am very new at this so I would love some directions.
    Thanks!

  5. My project is to turn the plywood subfloor of the kitchen into a the surface floor. I pounded in the nails, filled in the holes and cracks with wood fill, sanded, cleaned the floor very thoroughly, applied two coats of primer, 2 coats of life deck color seal paint- for decks and floors. It looked great. But I wanted the surface to be glossy, durable and easy to clean since its in the kitchen. So I applied polyurethane using a roller. It came out nice in some places, but cloudy and showing the strokes in many areas. So I went to the paint store and asked them what to do. They sold me the polyurethane from the same company as the paint that is supposed to be compatible with it. So I lightly sanded the whole floor, primed it again, painted two coats again, and applied he polyurethane. Same result again! Cloudy. How can I fix it? Do I have to go back to sanding and priming again? And how do I apply the poly so that it doesn’t keep having this same problem?

  6. I stained my dining room chairs after sanding them all the way down. The problem I am having is that I let the stain dry for 4 hours then I applied polyurethne and the polyurethane is not adhering to the wood. I have never had this problem before.Why is the poly not sticking to the wood ?

  7. I applied a fresh stain to my 21 year-old, unsanded table. While it looks beautiful now, it is still tacky after 28 hours. I regret thinking I could stain without sanding.

    Could I wipe on a poly(urathane) minwax? I don’t want to start over- I only wanted to refresh the table while repairing a few scratches.

  8. I applied wood penetrating stain to a laminated strip. The directions on the strip said not to sand it. After 2 days, , the surface is still tacky. I live in Florida and the humidity is high but I finally brought the strip inside under A/C. I do not think any of the stain can fully penetrate the strip so I hesitate to wipe it down. Any other suggestions to keep the color so it matches my cabinets?

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