Polyurethane is a popular protective finish for wood projects, prized for its durability, abrasion resistance, and bright glossy sheen. However, many DIYers encounter frustrating problems — such as brushmarks, bubbles, clouding, cracking, and adhesion issues — when applying polyurethane topcoats. 

    Don’t despair if your polyurethane finish doesn’t turn out perfectly — there are effective solutions.

    With some troubleshooting, you can salvage the finish and achieve the smooth, durable result you want. This guide covers common polyurethane finishing problems and methods to solve them so you can get a flawless, professional-looking finish.

    Application Issues

    Polyurethane finishes should dry in a matter of hours and not bleed oil. If you experience problems with drying or bleeding, these are some probable causes: 

    • Using an old or partially used can of finish can cause issues with proper drying and curing. The finish may have thickened over time or been contaminated. We recommend always using a fresh can.
    • Extreme temperatures can affect polyurethane and prevent proper curing. Avoid storing or applying finish in very cold or hot conditions.
    • Failure to stir the finish thoroughly before use is a common mistake. The solids and resins can separate, so mix polyurethane for three to five minutes before each use.
    • Applying outside the manufacturer’s recommended temperature and humidity range leads to problems. Typically, ideal conditions are 60°F to 80°F and 30% to 60% humidity.
    • Oily woods like rosewood, teak, ebony, and cocobolo contain natural oils that can interfere with polyurethane’s bonding and curing. Special preparation may be required.

    Evaluating the Finish

    Once the polyurethane finish is applied, you need to evaluate whether it cured properly. Check the finish for signs of ongoing bleeding, uneven gloss, tackiness, or other flaws. 

    If the finish has stopped bleeding oil and feels dry and hard, fix the uneven gloss by gently wiping it with a rag dampened with mineral spirits, followed by a clean, dry cloth. Ensure proper ventilation when working indoors with mineral spirits.

    If wiping doesn’t even the sheen, lightly sand with 220 grit sandpaper and apply a fresh coat of polyurethane. Purchase a new can from a different retailer if the batch is defective.

    Here’s the good news — if you run into problems with your finish, there are ways to troubleshoot and correct them short of having to strip the finish and start over completely.

    Today’s Homeowner Tips

    In some cases, though, if problems persist, the only recourse may be to strip the finish and begin again. You can find chemical strippers at most hardware stores.

    So, Is Solving Polyurethane Problems Worth the Effort?

    Polyurethane is durable and has protective qualities. When appropriately applied under proper conditions, it performs exceptionally well. In our experience, solving problems with the finish takes time and effort, but it is worthwhile before stripping everything and starting over.

    Follow all manufacturer’s instructions for preparation, mixing, application, and drying to prevent issues. If problems occur, try the steps above to correct them before removing the finish. With care and patience, you can get polyurethane to deliver an attractive, long-lasting finish on your project.

    FAQs About Polyurethane Finishing Problems

    How can I prevent bubbles and blisters in the polyurethane finish?

    Bubbles are the result of moisture or air trapped under the finish. Ensure the wood surface is completely clean and dry before applying polyurethane. Apply thin coats, brushing out any bubbles as you go. Allow proper drying time between coats.

    Why does polyurethane sometimes turn white or cloudy?

    Cloudiness is caused by moisture trapped under the finish, often due to inadequate drying time between coats. Always allow the recommended drying time before recoating.

    What causes blotchiness or an uneven finish?

    Applying polyurethane too thickly, failing to stir it properly, extreme temperatures during application or drying, and recoating before proper drying can cause unevenness. In our experience, following all manufacturer’s guidelines helps avoid an uneven finish.

    How can I get polyurethane finishes to stop feeling tacky?

    A tacky finish that never dries hard is caused by poor preparation, inadequate drying time between coats, applying in very humid conditions, or a bad batch of finish. Scrubbing with steel wool and applying another coat may help.

    Why do I have white spots on my finish after it dries?

    The finish can develop white spots if it is applied too thickly. High humidity levels or sunlight exposure during application can also cause white spots. We recommend keeping coats thin and allowing proper drying times to prevent white spots on your finish.

    Editorial Contributors
    avatar for Amy DeYoung

    Amy DeYoung


    Amy DeYoung has a passion for educating and motivating homeowners to improve their lives through home improvement projects and preventative measures. She is a content writer and editor specializing in pest control, moving, window, and lawn/gardening content for Today’s Homeowner. Amy utilizes her own experience within the pest control and real estate industry to educate readers. She studied business, communications, and writing at Arizona State University.

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    photo of Lee Ann Merrill

    Lee Ann Merrill

    Chicago-based Lee Ann Merrill has decades of experience writing and editing across a wide range of technical and scientific subjects. Her love of DIY, gardening, and making led her to the realm of creating and honing quality content for homeowners. When she's not working on her craft, you can find her exploring her city by bike and plotting international adventures.

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