What is Fisheyes in Paint – Causes with Removal Tips

what causes fish eyes in paint

If you use spray paint on furniture, cabinets, or most other surfaces, you may notice an issue commonly called “fisheyes.” It’s called so because of its appearance.

You can always clean the surface, which rids the area of fisheye, but that does not always work if the paint reacts to a contaminant that is inside the cracks of the wood.

If you want to stop the fisheye from happening, you will need to learn a basic application technique.

However, before you attempt this technique, it is crucial to understand what causes fisheye in the first place.

So, let’s start with the basics. And then, we will look at ways to prevent and remove the fisheyes problem.

What is Fisheyes?

These are defects that show up as small, circular shapes that have a crater or depression in the center.

You may see them as white dots or simple circles of paint with a separation around them.

Because they look a lot like the eyes of fish, that is where the fisheye name comes from. You may also know them as pits, craters, or saucers.

A fisheye tends to show up when you apply a coat of paint to the surface or just after the surface has been coated with paint.

Why Does Paint Fisheye Occur?

The cause of the fisheye is a contaminant, something on the surface that reacts to the paint being applied.

Such contaminants can vary, but the main ones are chemicals, oil, water, and substances that are silicone-based in nature.

If any of these contaminants have found their way to the surface or have been trapped in your paint gun, you will most likely face fisheyes problem when painting.

Besides surface contamination, coating too thin can sometimes cause fish eyes and pin holes. This is mainly observed in epoxy resin coatings when poured less than the recommended depth.

Removing Fisheye Craters from the Surface

Of course, all the preparation in the world may not entirely prevent fisheyes from appearing.

If you see a fisheye developing, the first step should be to remove the contaminant. Just trying to cover over the paint with another layer of paint only means you are creating yet another fisheye.

It can be quite tedious to remove the craters and the contaminants if you have many fisheyes on the surface. It’s one thing if you only must remove one or two, but dozens can make the effort that seems not worth it.

So, in that case, you should consider removing all the paint before cleaning the surface thoroughly and trying again.  

Method 1- Sanding or Stripping

The best way to remove paint and lacquer fisheye is to sand the area to remove the contaminant and then use a stripper or thinner to get rid of the finish.

If you have coarse grit sandpaper, this will work quite well. However, you must be careful not to damage the surface.

Otherwise, a chemical stripper is recommended.

But always try sanding first as that is the most effective way to remove the paint and the contamination.

You can try a combination of 220-grit sandpaper and lacquer thinner if you are spraying pre-catalyzed lacquer on the surface. This should remove all the spots on the wood.

If the fisheye forms over a knot in the wood, it means that some type of contaminant is trapped inside the knot or cracks.

If that contamination is deep enough, it will be almost impossible to remove. However, there is a spraying technique that can solve this problem.

Method 2 – Fisheye Eliminator

This is a chemical additive used to remove the surface tension, which usually contributes to creating fisheye.

Sherwin Williams suggests not to use fisheye eliminator in undercoats or basecoat colors. If you see fisheyes appearing in a basecoat, you should instead allow the color to flash and then spray a mist coat over the affected area to fix the fish eye problem.  

In case the paint has already dried, it’s better to sand the surface to a smooth finish below the fisheye cratering and then refinish.

The additive is something you should only use if everything else has failed. While effective, the additive will add silicone and other chemicals into the sprayer.

So, while it may work on this project, for future projects, it will create fisheyes unless you thoroughly clean the lines.

Plus, you will need to choose a fisheye eliminator that compliments the paint or clear coat lacquer you spray.

How Can You Prevent Fisheyes from Happening?

The first method to prevent fisheyes is to properly maintain the equipment you use for painting, varnishing, or powder coating.

You must use an air filtration system to prevent paint contamination for spray painting. If you have a solid separator and air filter on your compressor, that will help reduce the chances of contamination.

You will also need to regularly maintain your air compressor, including cleaning the intake valves, changing the air filter, and draining away any condensation. This will reduce the contaminants that otherwise might find their way into the paint.

In addition, you will need to inspect the HVLP paint gun and clean it between uses. If you do not clean it properly, you will likely get fisheyes. Be sure to clean it between the coats.

Plus, you can also purchase a last-chance inline air filter to catch any contaminants that may be in the lines.

Always spray light mist coats to prevent fish eyes

Instead of layering one or two heavy coats on the surface, try several light coats first. Let them dry, and then apply a heavier coat.

This method can work for lacquer or paint- but it can be time-consuming, especially if you have a large project to complete within a specific deadline.

So, if you have tried other methods and failed, this one should work. Be sure to lightly sand between mist coats for an even smoother finish.

Cleaning to avoid fish eye paint problems in the paint

To prevent contamination from being on the surface, you will need to clean it properly.

Products such as Krud Klutter or TSP are pretty good at removing most forms of contamination, according to dengarden. Be sure to use a coarse cleaning pad to scrub the surface with the cleaner and then rinse with clean or purified water.

This is especially true when using TSP, as all residues must be removed entirely.

Another cause of fisheyes is having a silicone-based substance get into the metal or on the surface of the project that you are painting.

All it takes is slight contamination from any source to create a fisheye.

To help avoid this possibility, use a paint prep solvent before priming and painting. This will clear away any impurities that might’ve found their way onto the surface.

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