Concrete floor coatings contractors know that achieving a smooth durable finish can sometimes be challenging depending on a variety of factors. It’s important to have basic troubleshooting knowledge and an understanding of common problems so you can quickly resolve any issues that arise in the field. In this guide, we’ll break down the most frequent problems encountered during installation and share expert tips on how to address them effectively to ensure your concrete coatings come out looking perfect every time.
This blog post provides a cheat sheet of those common concrete coating issues, their causes, and possible solutions to help you diagnose and tackle these challenges with confidence.
Bubbling or Blistering
What to look out for:
- Small bubbles or blisters appear on the surface of the coating.
- Blisters may form immediately after application or within a few hours/days.
Causes & Course of Action:
- Trapped Moisture
If the concrete is not fully cured or there is moisture under the surface, the moisture vaporizes when the coating is applied, causing bubbles. In order to find out if this is the cause, you can cut into one of the bubbles to determine if there is trapped moisture within. If confirmed, it is advised to install a moisture remediation system and then recoat. - High Application Temperature
Applying the coating in excessively hot conditions can cause the coating to cure too quickly, trapping air underneath. If this is the case you will need to grind down the coatings and reapply when temperatures are descending or climatize the area. - The Coatings has Been Applied Too Thick
A thick layer of coating can lead to excessive vapor pressure build-up, resulting in bubbling. If you’re concerned that you’ve applied the coating too thick, grind it down and refer to technical documentation for the proper coverage rates prior reinstallation. - Coating Is Applied In Direct Sunlight
If the coating was applied in direct sunlight, it may have cured too quickly leading to bubbles or blisters. If this is your cause, grind down the coating and reapply when the sun and temperature are descending. - The concrete is too porous
The concrete may have been too porous. In this case, you can grind down the coating and reapply.The previous coating that you are removing will have filled in any of the porosity.
Peeling or Delamination
What to look out for:
- The coating is starting to peel or lift from the concrete surface, often in large patches.
Causes & Course of Action:
- Poor Surface Preparation
If the concrete isn’t cleaned, etched, or properly prepared, the coating will fail to adhere. If this is the cause, grind down the coating, ensuring a clean surface and reinstall. - Possible Contaminants
Oils, dust, grease, or any other contaminants on the surface can prevent proper bonding between the coating and the substrate. If this is the case, you’ll need to identify what the contaminant is and install a remediation system formulated to mitigate that issue. - Moisture Issues
Concrete that retains moisture can cause delamination, especially if a vapor barrier isn’t used. In this case, you will need to grind down the coating and install a moisture remediation system. - Improper Mixing
If the coating components aren’t mixed properly, it can lead to adhesion failure. You will need to remove the coating, review the mixing instructions and reinstall.
Cracking
What to look out for:
- Cracks appear in the coating, either right after application or over time.
Causes & Course of Action:
- Substrate Movement
Concrete naturally expands and contracts with temperature and moisture changes, which can stress the coating and cause cracks. The best course of action is to install a flexible coating system. Perform structural repairs to the concrete slab such as stitching and or epoxy injection. - Excessive Thickness
For solvent based coatings, excessive thickness can cause solvent entrapment which leads to cracks in the coating. If this is your cause, remove the coating and reinstall at the correct thickness, referencing your coverage rates. - Inadequate Curing:
Epoxy coatings that are installed in conditions that are too cold can develop surface cracks and defects. Mechanically abrade the coating, patch as needed and recoat.
Discoloration or Uneven Color
Symptoms:
- The coating has patches of varying color or looks inconsistent across the surface.
Causes & Course of Action:
- Improper Mixing
Inconsistent mixing or not pre-mixing factory pigmented materials can lead to color variations. Additionally, failure to box multiple lots/batches, making the material uniform, will also cause color variations. In this case remove the coating and reinstall. - Application Technique
There are a few ways that application techniques can lead to uneven finishes. If you’re using multiple tools such as rollers and brushes, or if you waiting more than 5-10 minutes pass before cutting in. In these cases, you should sand recoat. - Temperature and Humidity Fluctuations
Environmental conditions, such as rapid temperature changes, can affect how the coating dries and cure, causing discoloration. If this happens you should sand and recoat when environmental factors are steady. - Coating Thickness
Uneven application of the coating can result in darker or lighter areas. If this is your cause, sand and recoat being careful to apply evenly. - Product Defect
While rare, epoxy, polyurethane and polyaspartic coating can sometimes have color stability issues. In these cases, you will need to sand and recoat, ideally with a quality-controlled material batch.
Chalking or Powdering
Symptoms:
- A fine, powdery residue appears on the surface after the coating has dried or been exposed to the elements.
Causes & Course of Action:
- UV Exposure
Over time, exposure to sunlight can break down coatings, causing them to chalk. The solution here is to clean the coating, sand and re-coat. - Poorly Cured Coating
If the coating hasn’t cured properly, it can break down more easily. Clean the coating, sand and re-coat. - Low-Quality Coating
Some coatings are more susceptible to chalking. Clean the coating, sand and re-coat with a high-quality Aliphatic topcoat.
Inconsistent Gloss or Sheen
Symptoms:
- Some areas of the coating appear shinier or duller than others, creating an uneven sheen.
Causes & Course of Action:
- Improper Application
Using different tools or inconsistent application methods can cause uneven gloss. With certain coatings, over application can lead to film defects such as micro bubbles or foam. Remove coating, if necessary, otherwise sand and recoat using the proper coverage rate. - Inconsistent Coating Thickness
Thicker areas of the coating often appear glossier due to the reflective surface. Sand the coating if necessary and apply an additional coat. - Curing Conditions
If the coating cures at different rates across the surface, it can affect the final appearance. Additionally, the cured gloss of epoxy coatings can be negatively effected when they cure at low temperatures and high humidity. Sand the coating and reinstall once the proper curing conditions can be achieved.
Streaking or Roller Marks
Symptoms:
- Visible lines or streaks appear in the coating, especially in areas where rollers or brushes were used.
Causes & Course of Action:
- Improper Application
Roller marks are often caused by improper process or technique. When the material is not spread evenly and back rolled properly roller lines will occur. Sand and recoat the floor using proper technique. - Drying Too Quickly
If the coating begins to set up during the installation process it can leave streaks or roller marks. Sand the floor and recoat, making sure that whatever process issues or environmental problems have been corrected. - Too Much Coating on the Roller
Using a roller that is too saturated can cause heavy lines. Sand and recoat the floor using proper technique.
Poor Adhesion in High-Traffic Areas
Symptoms:
- The coating begins to wear or lift in areas with heavy foot or vehicle traffic.
Causes & Course of Action:
- Incorrect Product Choice
Some coatings are not designed for high-traffic areas and can wear down faster. Select a coating that is specifically formulated for high-traffic areas, such as industrial-grade epoxy or polyaspartic coatings. - Improper Surface Preparation
If the surface isn’t adequately prepped or cleaned, the coating may not bond properly. Select a coating that is specifically formulated for high-traffic areas, such as industrial-grade epoxy or polyaspartic coatings.
- Too Thin a Coat
In high-traffic areas, a thinner coat is more likely to wear off quickly. Apply a thicker coat or multiple layers for additional durability
Final Thoughts
Understanding common concrete coating issues and their causes is essential for successful installations. Whether you’re dealing with bubbles, cracks, peeling, or discoloration, diagnosing the problem early and addressing it effectively can prevent costly repairs and extend the life of the coating. Always follow best practices for surface preparation, mixing, and application, and choose the right product for the job to achieve the best results.