Epoxy Coatings and High Humidity Application Precautions
High heat and humidity can cause challenges when applying resinous floor coatings. Below are some of the top concerns when applying epoxy coatings in warmer weather and the precautions you can take to potentially avoid resinous floor coating failures.
High Temperatures & Epoxy Floor Coatings
Decreased Pot Life/Less Working Time: In higher temperatures the cure time of an epoxy coating will speed up, leaving you less working time. Typically temperatures higher than 90 degrees F may cause the epoxy to become tacky and difficult to apply.
It is also important to consider that higher temperatures will decrease your pot life. When this occurs, the epoxy coating will start to cure while still in the mixing pail. To avoid this, mix smaller batches when you are applying an epoxy coating in higher temperatures. As always, review the manufacturer’s technical data sheets for recommended application temperatures.
Outgassing: When outgassing occurs, air bubbles can form in the epoxy coating. This phenomenon occurs when temperature increases; causing air and moisture vapor to be emitted from the concrete slab. If you notice that air bubbles have formed on the epoxy floor coating installation, you will need to sand down the coating and reapply.
If the outgassing occurs between coats when applying a multi-step resinous floor system; sand the coating down and reapply BEFORE applying any subsequent coats.
Common Resinous Coating Issues Dues to High Humidity
Bonding Issues: Increased moisture in the air can cause condensation on the concrete surface; causing issues during the bonding & curing process. The manufacturer’s product technical data sheets will provide recommendations on relative humidity application ranges.
Cure times: In high humidity, epoxies & urethanes may take longer to cure due to the increased moisture in the air. Be sure to consider that extra time may be required between coats when applying during high humidity.
Blushing: Blushing can occur when polymerization takes place at high humidity. This develops as a surface oiliness, exudate, or whitish spots in the resinous coating. Blushing appears as a milky, hazy effect in clear resinous coatings and may cause lack of gloss in pigmented coatings. Although high humidity is not the only factor that contributes to blushing, it does play a major role in the appearance of blush.
What are some of the best ways to avoid these issues in the hot, humid summer days?
- Consider waiting to apply the resinous floor system until late evening when temperatures may decrease slightly.
- Mix smaller batches to ensure you only mix what you can apply before the coating begins to cure.
- In confined spaces, the use of industrial de-humidifiers may also help create ideal curing conditions of an epoxy floor coating system.
- Epoxy/urethane coating systems that are sensitive to high humidity levels should not be applied when relative humidity is above the manufacturers recommended levels. Consult with your manufacturer for specific product recommendations.