When we talk about car paint bubbles, there are several different types and many different causes.
For this article, we will talk about some of the most common issues but the main focus will be on the restoration paint jobs. I see so many problems with car paint bubbles on classic car restorations, although any work on a newer car can have the same issues.
I see thousands of dollars spent on good paint jobs for these classic cars just to be ruined by a few simple things that could be avoided.
Car Paint Bubbles
- Tiny bubbles that are uniform across the panel: these types of bubbles most likely are caused by moisture in the paint process. Painting a vehicle with too much moisture in the air lines will create a problem. As the moisture gets trapped under drying paint it will come to the surface within a short period, a few weeks or longer. Unfortunately, the repair for this is to refinish the panel.
- Solvent pop : this condition is due to the application of a clear coat. The painter is applying too much too fast. The way this looks is not so much like car paint bubbles but more of tiny pinholes in the surface. The solvent from the paint needs to escape but the top surface is skimming over faster than this can happen. Therefore, creating a trapped solvent. As that solvent does come out it creates a tiny pinhole in the outer layer. If it is not too severe, it can be sanded and buffed out.
- Car paint de-lamination: The paint is starting to break down as it gets older mainly from sun exposure. As the clear breaks down it will start to lose its ability to protect the base color. This starts as small bubbles and then moves to peeling. No solution but to strip it off and refinish it.
Larger car paint bubbles
Generally speaking, if you have anything from a pencil eraser to a quarter or even a half dollar size bubble, your looking at bigger problems. Most of the time it is due to the body work, poor paint prep, or rust. There are always exceptions. Let’s take a look at some issues:
Rust bubbles under paint
When we talk about rust under the paint it can be caused by a problem when the metal was exposed prior to painting, or for old paint and OEM paint the most likely source is from the back side. If there was a scratch or chip down to the metal it may have started to rust. But a bubble rusting from the exposed area or from underneath is fairly evident and self explanatory. We are more concerned of a car paint bubble as it pertains to a refinish process. A prime example is a vehicle that was in our shop and the painter was getting ready to put primer on a fender he had stripped down to the metal. But he decided to leave it till after lunch. While he was gone, another person had come over to the car and for some reason leaned up against the fender with his hand on the bare metal. When the painter came back he went ahead and primed the fender. Continued to refinish the area. A month later there were little bubbles on the fender in the shape of a hand print. The body can give off a bit of salt in your sweat as well as oils from your skin. That is why it is so important to clean the bare metal surface good and prime it right away. There is proper priming procedures also which we will discuss later.