Fish eyes are aggravating imperfections in the surface of an epoxy coating that, as the name suggests, resemble the eyes of a fish.
Identifying Fish Eyes
Fish eyes are round separations or indentions in the floor finish that look a lot like a crater with a protruding rim around the perimeter and that contain a small dot in the centre – or to put it another way they look uncannily like their namesake.
The Cause of Fish Eyes
Fish eyes occur when there is a difference in surface tension between the coating and the substrate.
Contamination on the substrate or underlying surface is one of the most common causes of this surface tension. If there is anything such as surface oils, animal fats, vegetable oil, grease, silicone or petroleum based products still in the area when the epoxy coating goes down then there is a high chance of fish eyes appearing in the floor.
Another key reason for fish eyes is that the new epoxy coating has been applied on top of a tacky primer that has not properly dried or cured. The third main root of fish eyes is the use of mineral spirit, either for cleaning the floor or as a thinner, as it is not compatible with epoxy coatings.
Preventing Fish Eyes
To prevent any problems it is essential to properly prepare the substrate prior to applying the coating. This includes sufficient sanding and making sure that all petroleum-based contaminants are removed with an oil & grease emulsifier, followed by a thorough chemical cleaning with caustic acid and detergent.
A good tip is to check whether the cleaning rag was contaminated with other types of solvent, as it is likely that if other solvents were used previously then the applicator may have inadvertently used one to clean the surface that will result in imperfections.
Repairing Fish Eyes
The only way to repair fish eyes or other imperfections caused by oil or grease residue is to thoroughly sand the surface of the area, then follow these steps:
- Thoroughly clean the area again, making sure that you remove all silicon, oil or grease.
- Before applying anything, go back over the area with a vacuum or clean the area with a tack rag to ensure that all debris is removed.
- When recoating, only apply one unit at a time and monitor the new floor closely to see if the fish eyes reoccur.
If you’d like to find out more, get in touch with Flowcrete India’s resin flooring experts by clicking here. You can see also see a presentation by Flowcrete India on industrial flooring problems by clicking here.