When painting a house, be it the inside or the outside, you want the paint to last as long as possible and look fresh and clean all the time. Unfortunately, that’s not always possible, as paint is highly susceptible to damage.
Blistering is another word for paint bubbles that result from paint not adhering to the surface. Blisters can burst over time and stay put, or the paint can peel.
If you were wondering what causes paint to bubble, you came to the right place. Let’s find out!
What Is a Paint Bubble?
There are two common types of paint bubbles. The first one we will discuss is moisture entrapment.
This happens when the underlying substrate has too much moisture. The heat of the sun heats up the paint and the underlying moisture turns into vapor. Since the vapor has no way of escaping, it tries to rise up, thus forming a bubble under the paint.
Solvent entrapment works the same way as moisture entrapment. The paint solvent evaporates and forms a bubble under the top coat of the paint. It can’t escape, so it tries to rise up.
What Causes Paint to Bubble?
There are some common reasons why paint bubbles or blisters. Knowing the reasons will help you understand what you’re doing wrong, and avoid getting paint bubbles in the future. Additionally, once you know why your paint created bubbles, you can take the steps to fix it.
Paint application over wet, dirty surfaces
This is one of the main reasons why bubbles form on walls and ceilings. Before you apply the paint, the surface needs to be completely clean and dry. People often neglect cleaning their walls, especially if there is no visible dirt or dust.
This step is crucial in avoiding bubbles. The dirt on the wall will stand between the wall and the paint, thus not letting the paint stick to the wall. It will result in paint bubbles.
The painting surface or surroundings were too hot
Image source: A-Design By Gustavo Arredondo, Inc.
Heat is common in rooms that have heat-generating appliances, such as kitchens, or rooms that are exposed to direct sunlight. The top coat of the paint can dry too fast because of the sun, while the undercoat won’t have time to dry. Thus, bubbles can form from underneath the top coat.
Check the wall for moisture before you start to paint. This is a very common problem with bathrooms and kitchens. The wall will be exposed to moisture and vapor, so the paint won’t be able to dry properly. It’s also common in basements. There is no proper ventilation, so it can be quite humid.
If none of the above causes matches your situation, check your home for termites. If you find any, that’s not a good sign. Termites can have an effect on the infrastructure of your house.
Other causes of paint bubbles
- Painting in direct sunlight or on a hot surface.
- Using oil-based paint or alkyd paint on a wet surface.
- Exposing fresh paint to rain or humidity.
- Not priming or sanding shiny surfaces.
- Failing to remove dust from the surface.
How to Fix Paint Bubbles
Luckily, paint bubbles aren’t difficult to repair. However, we recommend preventing them by following the proper procedure when painting your walls.
Repair according to the cause of bubbling
First, you should identify the root of the problem.
- If only the newest coat is blistered, it’s probably a result of heat.
- If several coats are blistered, the blister was caused by moisture.
How to repair paint bubbles caused by heat
- Before you make any repairs, you need to let the paint dry completely. This can take up to a couple of weeks with some types of paint.
- Lay some cloths on the floor around the area you’re going to repaint to collect debris. Wear a dust mask and goggles.
- Start by trying to scrape the bubble with a putty knife. If it peels off easily, the paint is not dry enough yet. Wait for it to dry so you don’t accidentally peel off a larger area of the paint.
- Scrape from the center. Remove the paint that comes off easily first.
- If the surface underneath is uneven, apply joint compound to repair it. Sand the compound until it’s smooth. Don’t forget to remove the dust from the sanding!
- Then, apply a coat of primer to the wall. This step is very important, as primer helps paint adhere to the wall.
- Wait for the primer to dry and repaint the area using high-quality paint.
How to repair paint bubbles caused by moisture
- Start by removing all loose paint by scraping the wall with a scraper or a wire brush.
- Then, eliminate the source of moisture. It could be poor ventilation in the room, so open some windows. Repair loose caulking.
- Sand the area thoroughly. Sanding will make the are rougher and create a specific texture. The paint will adhere to it with ease. Before you get to sanding, don’t forget to add a coat of primer to the area.
- Repairing blisters on inside walls is easier than on outside walls. If you’re working inside, getting a good and even layer of paint on the wall won’t be hard.
- Repaint the surface to the desired result.
How to Prevent Paint Bubbles
There are some things you can do during the painting process to prevent paint bubbles.
Prepare your wall correctly
Start by clean the surface. Wash the walls thoroughly. Even if you think the walls are clean, there are probably some invisible stains on them. Use a mild detergent and a sponge to wash the walls. Then, rinse them with warm water.
If you’re working with new drywall, wipe off all the dust. Prime the surface before you get to painting. Let the primer dry completely.
Stir the paint slowly
Stirring paint too quickly for a long period of time can create air bubbles in the paint. Stir for a short amount of time and do so slowly. Use a wooden stirrer or a paint-mixing power drill.
Apply paint gradually when using a roller
Slow down if you see bubbles forming.
Avoid applying oil-based paint directly over latex paint
Oil and water bases don’t bind well. There will be no adhesion between the coats, resulting in blistering of the oil-based coat.
Ending thoughts on what causes paint to bubble and how to fix this
Sometimes paint bubbles show up right away. Other times they take their time and show up later. Either way, they ruin the look of the wall and are not a pleasure to have in the house. Luckily, it’s not the end of the world and you can easily get rid of them yourself.
If the bubbles are a result of moisture, it’s best to wait till everything is completely dry to repair them. If you go in on the wet paint, you will just repeat the same mistake.
Always try to avoid painting in extra hot or humid conditions. As you already know, adding moisture to the mix is not a good idea. You can install vents or exhaust fans to ventilate the room you’re in and decrease the humidity.
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