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Protecting Floors from Sunlight

June 25, 2020

Whether your new Dur-A-Flex floor installation is indoor, outdoor or somewhere in-between, being aware of sunlight exposure, directly or indirectly, is very important during product selection, application, curing, and ultimately the service life of the floor. Let’s explore these in more detail.

Whether from interior fluorescent lights or direct sunlight exposure, epoxies and Poly-Crete products are negatively impacted by ultraviolet (UV) exposure (except Poly-Crete Color Fast). Basically gray colors will change to a “greenish” color (see picture) and red colors turn “pinkish.” In addition to ambering, epoxies can also become dull and chalky over the course of time depending upon the extent of the UV exposure.

If working on an interior project be sure to check the direction of sunlight exposure as it will be moving across the sky throughout the day. If sunlight exposure is unavoidable during the installation, all windows allowing sunlight into the room will need to be covered to protect the floor during the application and cure process. If engineering controls are not sufficient to block the sunlight due to room layout, height, etc. then working at night may be the only option. This is even more important for exterior applications; if sunlight exposure cannot be avoided or controlled the work will have to be performed during low-light and nighttime conditions.

Sunlight can also negatively impact the application process.  It can heat the slab which can contribute to reduced working time and outgassing in the concrete.

To minimize outgassing and the formation of outgas bubbles, primers and Poly-Crete basecoats should be applied when the substrate temperature is warmest and the slab temperature is decreasing. As the slab cools the concrete “inhales” and draws the resinous material into the prepared slab. The substrate must be protected from direct sunlight during the application and curing process to block the sun from heating up the substrate during the application and curing process. 

Please see Tech Notes “Outgassing” and Tech Tips “Best Time to Prime” for more details on outgassing and how to minimize it from occurring.

To avoid degradation from UV exposure always apply a final topcoat of Armor Top or High Solids Poly-Thane #2 aliphatic urethane topcoats over all epoxies (except Novolac). Also, consider using other UV stable topcoats and flooring systems such as Accelera 100% solids fast curing products, Cryl-A-Flex MMA based acrylic floor products, Color Fast cementitious aliphatic urethane topcoat, or the Hybri-Flex systems options.

Bart Rinaldi
Technical Manager – South


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