Bubbled paint on exterior walls.

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We have sanded back our weatherboard house, then used an oil based primer followed by water based top coat. We are now seeing everywhere we have primed lots of bubbling paint. What is this from and how do we fix it?

4 Responses

  1. I apologize in advance for not answering this question with a definite answer. I too, in over 30 years in the paint business have had this happen and have never had a conclusive answer.

    I have tried making sure the weatherboard had sufficient backside ventilation. I have tried both alkyd and latex finishes. I have tried everything I can think of to no avail. If you purchased the paint at a paint store, ask them for their help.

  2. Should have used acrylic latex primer or conversely an oil base topcoat…Unfortunately topcoat s/b removed.

  3. The bubbling paint issue you are experiencing after priming with an oil-based primer and applying a water-based top coat on your weatherboard house is likely due to underlying paints or stains becoming reactivated, either by chemical action or heat due to color change. This mismatch of paint types can lead to bubbling or blistering as the solvents in the different types of paint can react adversely with each other.

    I’ve had this happen on old homes that were first stained with a linseed oil/tar mixture a hundred years ago. This is then reactivated, degassing and pushing this gas through many layers of old oil based and water based paint to finally cause my new flexible paint to form bubbles. Scrape the bubbles to see what’s underneath.

    To fix this issue, you will need to remove the bubbling paint and properly prepare the surface before reapplying the top coat. Here’s a step-by-step guide to fixing the problem:

    1. **Assessment**: Identify all areas where the paint is bubbling. Mark these areas for removal.

    2. **Surface Preparation**: Use a paint scraper or putty knife to carefully remove the bubbling paint. Sand the edges to create a smooth transition between the bare surface and the existing paint.

    3. **Cleaning**: Thoroughly clean the exposed surface to remove any dust, dirt, or debris. A damp cloth or sponge can be used for this purpose.

    4. **Priming**: Since the previous primer may have caused the bubbling issue, it’s crucial to choose a compatible primer to ensure adhesion between the layers. Opt for a high-quality bonding primer that is suitable for both oil-based and water-based paints.

    5. **Repainting**: Once the primer has dried according to the manufacturer’s instructions, you can proceed to apply a new coat of water-based paint. Make sure to follow the recommended drying times between coats.

    6. **Preventive Measures**: To avoid similar issues in the future, ensure that you use compatible paint products. If transitioning between oil-based and water-based paints, consider using a primer specifically designed for such transitions.

    By following these steps and using appropriate products, you can effectively address the bubbling paint problem on your weatherboard house and achieve a smooth, durable finish. Remember, proper surface preparation and paint compatibility are key factors in preventing paint adhesion issues.

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