Putting a new coat of paint on your walls is a relatively easy way to improve the appearance of your home. But if you don't paint under the right conditions, you may start to see ugly protrusions forming on the surface.

As the name suggests, paint bubbles—also known as blisters—look like swollen air pockets that have developed under a section of paint. This eyesore occurs when the paint does not properly adhere to the wall, leaving some space between the paint and the surface.

The process of repairing paint bubbles involves removing them from the wall and repainting the surface. However, you'll also need to make sure the surface is properly treated or you'll run into the same problem again.

Repair

Not all paint bubbles need to be repaired. Ace Paints, a company in Pittsburgh, Pennsylvania, says some bubbles may appear soon after painting but go down once the paint has dried.

Paint bubbles can be removed by simply scraping them away from the wall. A paint scraper or putty knife is suitable for this purpose. Jill Davis, writing for SFGate, says you should scrape the whole area if it is affected with a rash of small bubbles.

Once the bubbles has been removed, there will still be a rough edge between the paint edges and the underlying surface. Use sandpaper on these areas to create a smooth surface.

In some cases, the underlying surface may be uneven, pitted, or otherwise flawed. Use joint compound to fill in these imperfections and sand it to create a smooth surface.

Alternatively, you might try to fix the problem with an iron. Ace Paints says this process involves removing the water from the iron, then pressing the hot surface against the bubbles for 30 seconds to one minute. Once the wall has cooled to a point where you can touch it, you can use your fingers to smooth out the bubbles.

Surface preparation

Paint bubbles can form for many reasons, but most of them relate to the condition of the wall. If you have not properly prepared the surface, the paint will be less likely to adhere to it.

Grease, dirt, and dust will all make it harder for paint to stick to a wall. Use a wet cloth to wash the surface. It is important to take this step when repairing a paint bubble, as it can remove the cause of the problem as well as any dust left on the surface from sanding. Allow time for the wall to dry, since bubbles can also form if you try to paint a wet surface.

Moisture can also cause paint bubbles to form. The paint company Sherwin-Williams says moisture might be seeping through the walls, or that damp conditions could be occurring in areas such as the basement.

If you think there is too much moisture in the room, take steps to remedy this issue before completing the repair. You might have to replace caulking or install vents or exhaust fans to cut down on humidity.

The weather conditions at the time of painting can have a significant effect on the paint. Innovation Painting, a company based in San Jose, California, says painting in direct sunlight or hot conditions can be especially problematic. The high temperatures will cause the top of the paint to dry but also cause solvents to vaporize, with the expanding gases pressing against the dried paint to form the bubble.

Turning on the air conditioner when painting in hot conditions will help alleviate this problem. You should also avoid painting within four hours of rainfall, since humid conditions will increase the likelihood that bubbles will form.

Paint bubbles can occur with any type of paint, but they are more common with latex and acrylic paints. When painting over an existing layer of paint, never put an oil-based paint over latex or acrylic paint.

Repainting

Once a bubble has been removed and the surface sanded and cleaned, you'll be able to put down another layer of paint in this area. Don't forget to put down a coat of primer first, as this material will allow the paint to adhere better.

Allow the primer to dry before putting down another layer of paint. Davis says the manufacturer will recommend how long the primer should take to dry.

Paint over the primer to create a uniform appearance with the rest of the wall. You can also choose to put down a second coat of paint once the first coat dries.