Understanding the Causes of Industrial Floor Coating Peeling and Bubbling

Industrial floor coatings are essential for protecting concrete floors in warehouses, factories, and commercial spaces. However, one of the most frustrating problems that facility managers and contractors face is coating failure, particularly peeling or bubbling. These issues not only affect the floor’s appearance but also compromise its protective qualities and can lead to costly repairs.

Understanding the root causes of coating peeling and bubbling is key to preventing failure and ensuring long-lasting performance.

1. Moisture-Related Issues

a. High Moisture Content in Concrete

One of the most common causes of coating failure is excessive moisture in the concrete substrate. Concrete is porous and can retain water from rain, groundwater, or curing processes. When moisture tries to escape through the floor, it can create pressure under the coating, causing bubbling or blistering.

• Moisture Vapor Transmission (MVT): Concrete can emit water vapor. If the coating applied is not vapor-permeable, the trapped moisture builds pressure beneath the coating layer, leading to peeling or bubbles.

• Inadequate Moisture Testing: Failing to conduct moisture tests like the calcium chloride test or relative humidity probe before coating application can lead to applying coatings on unsuitable surfaces.

b. Hydrostatic Pressure

In cases where concrete slabs are on-grade or below-grade, hydrostatic pressure can push water upward from the soil, further increasing moisture levels and contributing to coating failure.

2. Poor Surface Preparation

Proper surface preparation is vital to coating adhesion. Without it, coatings are prone to peel or bubble.

• Contaminants: Dirt, grease, oils, curing compounds, or old coatings that are not fully removed can prevent proper adhesion.

• Insufficient Profiling: Concrete must be mechanically roughened (shot blasted, diamond ground) to provide a profile for coatings to grip. Smooth or laitance-covered surfaces result in weak bonding.

• Residual Moisture: Even if moisture tests are done, failing to allow the floor to dry thoroughly before coating leads to trapping moisture under the coating.

3. Incorrect Application Conditions

a. Temperature and Humidity

Applying coatings when the ambient or substrate temperature is too low or too high can affect curing and adhesion.

• Cold Conditions: Slow curing leads to weak bonding and moisture entrapment.

• High Humidity: Promotes condensation on the surface, trapping moisture beneath the coating.

b. Dew Point and Condensation

If the surface temperature is below the dew point, condensation can form, causing moisture to accumulate under the coating and resulting in bubbling.

4. Incompatible or Poor Quality Materials

• Wrong Coating Selection: Using a coating incompatible with the substrate or environmental conditions leads to failure.

• Expired or Improperly Mixed Materials: Using old or improperly mixed coatings reduces adhesion strength.

5. Structural Issues and Concrete Defects

• Cracks and Voids: Unrepaired cracks or holes in concrete allow moisture ingress and create weak spots.

• Plastic Shrinkage and Settlement: Movement in the slab can cause the coating to separate from the substrate.

6. Insufficient Curing Time or Overcoating Intervals

Applying topcoats too soon or after excessive delays beyond recommended windows can lead to poor intercoat adhesion and bubbling.

How to Prevent Peeling and Bubbling

• Conduct thorough moisture testing before application.

• Ensure proper and complete surface preparation.

• Select coatings suitable for substrate and environment.

• Control ambient temperature and humidity during application.

• Follow manufacturer’s mixing and application guidelines.

• Repair cracks and defects before coating.

• Use vapor barriers or moisture mitigation systems when necessary.

Conclusion

Peeling and bubbling of industrial floor coatings are almost always symptoms of underlying issues such as moisture intrusion, inadequate surface prep, or improper application. Preventing these problems requires careful assessment, preparation, and adherence to best practices in coating selection and application. By addressing these causes, you can ensure a durable, long-lasting industrial floor coating that maintains safety and aesthetics.