What are fish eyes in epoxy?

Fish eyes are a type of defect found in the coatings of surfaces that appear as small dimples. The relationship between fish eyes and coatings is similar to how potholes are created on roads.

A road’s surface can be considered as its coating, while water acts as the contaminant which causes the potholes. Here, however, the coating is epoxy and contaminants cause the formation of fish eyes.

The main cause for this phenomenon is an incompatibility between the surface and epoxy components. What happens during application is that an adhesive force among incompatible particles prevents them from being evenly distributed, thus resulting in defects like fish eyes.

Additionally, other factors such as oil-based residues, moisture contamination on surfaces or dust particles may also result in fish eye defects forming on surfaces within your workspace or garage floor.

How do I get rid of fish eyes in epoxy?

  • Try adding more epoxy resin to the container. This will make the surface tension higher, which helps prevent fish eyes. You can also try adding a little bit of MEKP catalyst to this additional resin and stir it well before you add it to your mixture. If you’re working in smaller batches, it’s important that they are completely full.
  • Make sure you’re stirring enough. Thoroughly mix everything together with a paint stirrer for at least three minutes after all of your resin is combined with a hardener. A longer mixing time is usually better when fabricating with epoxy, but be careful not to over-mix because this can create air bubbles in your product.
  • You may need to use a different brand or type of epoxy system if your project requires it or if you’ve already tried other solutions but still haven’t eliminated fish eyes from your epoxy batch. Using an epoxy that has been specifically developed for the conditions and environment of your project can make all the difference in eliminating fish eyes and preventing other types of defects from showing up in your cured material.

What causes fish eyes in epoxy resin?

Fish eyes are caused by contaminants in the epoxy resin. These contaminants can be dust particles, grease, wax or other substances.

The contaminants will not mix with the epoxy resin and therefore creates small cavities on the surface of the casting which resemble fish eyes.

  • Unsaturated oils (oil-based polyester resins)

Fish eyes can also be caused by unsaturated oils released from wood or your skin when handling a project without proper precautions, such as wearing gloves.

Oils will not mix with polyester resins and will create fish eyes on the casting surface.

How do you prevent fish eye?

Luckily, preventing fish eyes is easy if you know what to do. All of the following steps are extremely important:

  • Clean the surface thoroughly. You should be wiping it down with a solvent to remove any wax or oil.
  • Use a dewaxed epoxy. As I mentioned earlier, some resins will come with wax already in them, which can lead to fish eyes. Make sure your epoxy has already been dewaxed by the manufacturer so you don’t have to worry about this problem happening again!

How do you prevent fish eyes in epoxy tumbler?

  • Clean your tumbler before applying epoxy.
  • Do not use automotive polishes.
  • Do not use silicone polish.
  • Do not use wax.
  • Do not use acetone. (If you need to remove it, we recommend using mild hand soap and warm water.)
  • Do not use alcohol or other solvents in the cleaning process.
  • Use only a clean microfiber towel to clean your tumbler before applying epoxy.*Do NOT use paper towels or any other type of paper product to clean your cup; they will leave debris behind.*

Can you pour epoxy over cured epoxy?

You can pour epoxy over cured epoxy. It only works if the cured surface is smooth and clean, though. If there are air bubbles or dust particles on the first layer of cured epoxy, you’re going to have a bad time.

Pouring epoxy directly onto the wood surface without touching up any imperfections will result in more fish eyes than a sushi bar (and not nearly as delicious).

Be sure to sand down any large imperfections using 220 grit sandpaper, then try out some 400 grit wet sanding to really get things looking good.

You can also use some acetone mixed with fine steel wool to really get things looking smooth and shiny. Then rinse off the acetone with water, wipe dry with a towel, and make sure you allow it to fully evaporate before you pour your next layer of epoxy.

What causes dimples in epoxy?

The cause for dimples in epoxy is quite simple. As you’ll see below, the most common causes are typically related to surface preparation and/or application conditions.

  • Problems with surface prep: in these cases, the solution is to properly prepare the surface before re-applying a new coat of paint.
  • Inadequate cleaning of surface: If a surface was not adequately cleaned before applying primer or paint, problems can arise.
  • Inadequate sanding of surface: If a painted or primed surface was not sanded properly before applying primer or paint, problems can arise.
  • Use of incompatible primer: The wrong type of primer may have been used on an existing finish, causing incompatibility between the layers of coating which results in dimpling issues later on.
  • Use of incompatible paint: The wrong type of paint may have been used on an existing finish, causing incompatibility between the layers of coating which results in dimpling issues later on.
  • Use of incompatible cleaner: The wrong type of cleaner (such as one containing silicone) may have been applied to an existing finish prior to painting, causing incompatibility between the layers of coating which results in dimpling issues later on.
  • Use of incompatible wax and polish: The wrong type of wax or polish (such as one containing silicone) may have been applied to an existing finish prior to painting, causing incompatibility between the layers and resulting in fish eye later on.
  • Use

How do you fix dimple in epoxy resin?

After the curing process, you might notice a few dimples or fish eyes in the resin. This is when small imperfections form on the surface of an epoxy product. The good news is these can be easily repaired or avoided altogether with a little know-how.

Fixing Dimples Start by sanding off as much of the dimple/fish eye as possible using sandpaper (start with a more coarse grit and gradually move to finer).

Take your time here and don’t rush it! You want to use enough force to get rid of it but don’t overdo it and end up removing too much epoxy.

Once you’ve gotten rid of the majority of it, apply more epoxy on top (making sure to mix fresh resin) and let cure again for 24 hours.

Should you sand between coats of epoxy?

After waiting for 24 hours, the first coat will have cured enough that it won’t transfer onto your sandpaper. You can use a variety of tools to sand the epoxy: an oscillating sander, an orbital sander, or a hand block and paper.

We recommend using medium-grit sandpaper of around 150 or 180 grit. If you started with a very smooth surface on your project, you should be able to skip this step and go straight to wet sanding before applying the second coat of epoxy. Wipe off any dust that’s leftover with a microfiber cloth (don’t use paper towels because they leave lint behind).


The bottom line is this: you should never have to deal with fish eyes in your epoxy. Always use a quality epoxy, like TotalBoat 2:1 or 5:1 Epoxy Kits.

It’s manufactured to the highest standards and has no fillers, so it won’t cause fish eyes. Just make sure you follow the mixing and application instructions, and you’ll find that using epoxy is easier than ever!

Leave a Comment