Working With Art's Epoxy Repair System In Hot Weather

As the repair season progresses from spring to summer and hot weather sets in,
it’s important to keep a few basic practices in mind for the summer season.

Both Prime-A-Trate© and Flex-Tec HV™ are exothermic curing materials.
This means the cure takes place by generating heat during cross-linking.
The curing speed and temperature are directly related to the outside air
temperature, surface temperature, humidity and the size of the repair.




The most effective way to control excessive heat build-up
is by avoiding repairs in direct sunlight.


Thick layers cure faster than thin layers because of heat build-up and heat retention during the curing process. Thick layers on hot days can really build heat! In extreme cases, the epoxy material can get quite hot to the touch and begin to “steam” as the trapped air bubbles begin to heat and expand. To prevent extreme heating of the Flex-Tec HV™ and Prime-A-Trate© in hot weather we recommend a few summer-time precautions.

The most effective way to control excessive heat build-up is by avoiding repairs in direct sunlight. A building’s surfaces can reach 120 degrees or more when exposed to hours of direct summer sun. It’s best to always work on the shady side of the building and try to schedule large repairs early in the day while the air and surface temps are cool. If your schedule does not permit this consider placing a sunshade against the area several hours prior to executing a repair. Anything that will block the sun, i.e. Cardboard, scrap plywood, or scrap insulation board, will work well.

The next step is to store the unmixed cartridges in a cool place well before they are needed. A set of Flex-Tec HV™ left in a closed work truck all day will get quite warm even before mixing. Consider keeping the material inside an air-conditioned space or even storing a few sets in a lunch cooler.

Because large amounts of epoxy cure faster than small amounts consider doing large repairs in 2 to 3 separate layers to avoid excessive heat build-up.
Keep in mind that even small amounts of Flex-Tec HV™ and Prime-A-Trate© will cure quicker in hot weather. A repair that normally took 8 hours to cure at 70 degrees will take 1/3 to 1/4 of the time at 90 degrees.

Remember very large repairs can always be reduced by using clean wood block “filler” pieces to take up space and reduce the amount of Flex-Tec HV™ required. When using wood block fillers, remember to “butter” the bottom of the hole then butter all surfaces of the wood block. This coating will assure a good bond to all surfaces and reduce large voids of trapped air. Lastly, make sure the wood block sits well below the surface (at least 1/4”) to prevent problems with sanding and “ghosting” after painting. Time is needed for the wet uncured Prime-A-Trate© to sit and “dwell” on the surface and penetrate deeply into the wood fiber. Hot surfaces accelerate the cure and stop the penetrating process.

So what happens if the Flex-Tec HV™ gets extremely hot? Don’t be too alarmed. The Flex-Tec HV™ might start to smoke a little as the steam begins to rise and you might notice some expansion of the Flex-Tec HV™ as the trapped air bubbles heat and expand. The top exoterm (aka: the hottest-it-can-get) is 180 degrees. Wood will combust at 700 degrees. No risk of fire is possible.

Just like managing your own temperature by wearing a hat and sunscreen and by avoiding the hot direct
sun consider that your epoxy repairs also need a little management of their own.