Fisheyes are small, round craters that appear in a coating as it flows out, formed when a contaminant like oil, silicone, or wax repels the wet material away from a single spot.
Understanding Fisheyes in Coating Applications
Fisheyes are small, round craters that appear in a coating as it flows out across the floor. They form when a contaminant on the substrate, such as oil, silicone, or wax, repels the wet coating away from that single spot, leaving a tiny open crater surrounded by a raised ring of material.
What Causes Fisheyes?
Contamination is almost always the cause. Common sources include silicone-based caulks or lubricants, curing compounds left on new concrete, oil or grease tracked in on work boots, and even silicone spray used elsewhere in the building that drifts onto the floor before the coating is applied. Poor mixing or contaminated rollers can also introduce the problem.
Fisheyes vs. Pinholing
Fisheyes and pinholing can look similar at first glance, but they come from different causes. Fisheyes are craters caused by surface contamination repelling the wet coating, while pinholing is caused by air or moisture vapor escaping from the slab through the coating as it cures. Identifying which one you are dealing with determines whether the fix is better cleaning or better moisture and air management.
Practical Tips for Preventing Fisheyes
Clean and degrease the substrate thoroughly before coating, and avoid using silicone-based products anywhere near the job site. Keep tools, rollers, and mixing equipment dedicated to coating work and free of contamination from other trades. If fisheyes do appear, sand out the affected area, clean it again, and spot coat rather than assuming the next coat will fix itself.
Also Called
Cratering, cissing
